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Sample records for nonadiabatic dissociation dynamics

  1. Effects of chirping on the dissociation dynamics of H2 in a two-frequency laser field

    International Nuclear Information System (INIS)

    Datta, Avijit; Bhattacharyya, S.S.; Kim, Bongsoo

    2002-01-01

    We present the effects of frequency chirping of laser pulses on (1+1)-photon resonance-enhanced dissociation dynamics of H 2 . The dissociation occurs via two closely spaced nonadiabatically coupled intermediate levels which are in one-photon resonance or near resonance with the initial level. Predissociating levels embedded into continua are considered. When the first laser field is sufficiently intense and suitably chirped, the dissociation probability is enhanced by adiabatic rapid passage through the avoided crossing arising from the frequency swept radiative interaction. The whole population of the ground level can be effectively transferred to the intermediate levels by this technique facilitating the dissociation process by the second field. We also report the effect of frequency detuning and chirp width on the dissociation probability. Widths of the two peaks of the dissociation line shape increase with an increase in chirp width, resulting in the possibility of control in the dissociation yield. When the first field is a laser pulse of low intensity and constant frequency and the second laser frequency is chirped, predissociating levels take important parts in the dissociation dynamics and we obtain a signature of the nonadiabatic effect of the first step on the second step of photodissociation dynamics. This feature is due to the presence of the predissociating levels and the nonadiabatic mixing of two intermediate levels. All these results can be explained in terms of the adiabatic dressed levels

  2. Nonadiabatic electron wavepacket dynamics behind molecular autoionization

    Science.gov (United States)

    Matsuoka, Takahide; Takatsuka, Kazuo

    2018-01-01

    A theoretical method for real-time dynamics of nonadiabatic reorganization of electronic configurations in molecules is developed, with dual aim that the intramolecular electron dynamics can be probed by means of direct and/or indirect photoionizations and that the physical origins behind photoionization signals attained in the time domain can be identified in terms of the language of time-dependent quantum chemistry. In doing so, we first formulate and implement a new computational scheme for nonadiabatic electron dynamics associated with molecular ionization, which well fits in the general theory of nonadiabatic electron dynamics. In this method, the total nonadiabatic electron wavepackets are propagated in time directly with complex natural orbitals without referring to Hartree-Fock molecular orbitals, and the amount of electron flux from a molecular region leading to ionization is evaluated in terms of the relevant complex natural orbitals. In the second half of this paper, we apply the method to electron dynamics in the elementary processes consisting of the Auger decay to demonstrate the methodological significance. An illustrative example is taken from an Auger decay starting from the 2a1 orbital hole-state of H2O+. The roles of nuclear momentum (kinetic) couplings in electronic-state mixing during the decay process are analyzed in terms of complex natural orbitals, which are schematically represented in the conventional language of molecular symmetry of the Hartree-Fock orbitals.

  3. Modeling non-adiabatic photoexcited reaction dynamics in condensed phases

    International Nuclear Information System (INIS)

    Coker, D.F.

    2003-01-01

    Reactions of photoexcited molecules, ions, and radicals in condensed phase environments involve non-adiabatic dynamics over coupled electronic surfaces. We focus on how local environmental symmetries can effect non-adiabatic coupling between excited electronic states and thus influence, in a possibly controllable way, the outcome of photo-excited reactions. Semi-classical and mixed quantum-classical non-adiabatic molecular dynamics methods, together with semi-empirical excited state potentials are used to probe the dynamical mixing of electronic states in different environments from molecular clusters, to simple liquids and solids, and photo-excited reactions in complex reaction environments such as zeolites

  4. Ab initio multiple spawning dynamics study of dimethylnitramine and dimethylnitramine-Fe complex to model their ultrafast nonadiabatic chemistry.

    Science.gov (United States)

    Bera, Anupam; Ghosh, Jayanta; Bhattacharya, Atanu

    2017-07-28

    Conical intersections are now firmly established to be the key features in the excited electronic state processes of polyatomic energetic molecules. In the present work, we have explored conical intersection-mediated nonadiabatic chemical dynamics of a simple analogue nitramine molecule, dimethylnitramine (DMNA, containing one N-NO 2 energetic group), and its complex with an iron atom (DMNA-Fe). For this task, we have used the ab initio multiple spawning (AIMS) dynamics simulation at the state averaged-complete active space self-consistent field(8,5)/6-31G(d) level of theory. We have found that DMNA relaxes back to the ground (S 0 ) state following electronic excitation to the S 1 excited state [which is an (n,π*) excited state] with a time constant of approximately 40 fs. This AIMS result is in very good agreement with the previous surface hopping-result and femtosecond laser spectroscopy result. DMNA does not dissociate during this fast internal conversion from the S 1 to the S 0 state. DMNA-Fe also undergoes extremely fast relaxation from the upper S 1 state to the S 0 state; however, this relaxation pathway is dissociative in nature. DMNA-Fe undergoes initial Fe-O, N-O, and N-N bond dissociations during relaxation from the upper S 1 state to the ground S 0 state through the respective conical intersection. The AIMS simulation reveals the branching ratio of these three channels as N-N:Fe-O:N-O = 6:3:1 (based on 100 independent simulations). Furthermore, the AIMS simulation reveals that the Fe-O bond dissociation channel exhibits the fastest (time constant 24 fs) relaxation, while the N-N bond dissociation pathway features the slowest (time constant 128 fs) relaxation. An intermediate time constant (30 fs) is found for the N-O bond dissociation channel. This is the first nonadiabatic chemical dynamics study of metal-contained energetic molecules through conical intersections.

  5. Ab initio multiple spawning dynamics study of dimethylnitramine and dimethylnitramine-Fe complex to model their ultrafast nonadiabatic chemistry

    Science.gov (United States)

    Bera, Anupam; Ghosh, Jayanta; Bhattacharya, Atanu

    2017-07-01

    Conical intersections are now firmly established to be the key features in the excited electronic state processes of polyatomic energetic molecules. In the present work, we have explored conical intersection-mediated nonadiabatic chemical dynamics of a simple analogue nitramine molecule, dimethylnitramine (DMNA, containing one N-NO2 energetic group), and its complex with an iron atom (DMNA-Fe). For this task, we have used the ab initio multiple spawning (AIMS) dynamics simulation at the state averaged-complete active space self-consistent field(8,5)/6-31G(d) level of theory. We have found that DMNA relaxes back to the ground (S0) state following electronic excitation to the S1 excited state [which is an (n,π*) excited state] with a time constant of approximately 40 fs. This AIMS result is in very good agreement with the previous surface hopping-result and femtosecond laser spectroscopy result. DMNA does not dissociate during this fast internal conversion from the S1 to the S0 state. DMNA-Fe also undergoes extremely fast relaxation from the upper S1 state to the S0 state; however, this relaxation pathway is dissociative in nature. DMNA-Fe undergoes initial Fe-O, N-O, and N-N bond dissociations during relaxation from the upper S1 state to the ground S0 state through the respective conical intersection. The AIMS simulation reveals the branching ratio of these three channels as N-N:Fe-O:N-O = 6:3:1 (based on 100 independent simulations). Furthermore, the AIMS simulation reveals that the Fe-O bond dissociation channel exhibits the fastest (time constant 24 fs) relaxation, while the N-N bond dissociation pathway features the slowest (time constant 128 fs) relaxation. An intermediate time constant (30 fs) is found for the N-O bond dissociation channel. This is the first nonadiabatic chemical dynamics study of metal-contained energetic molecules through conical intersections.

  6. Nonadiabatic effects in electronic and nuclear dynamics

    Directory of Open Access Journals (Sweden)

    Martin P. Bircher

    2017-11-01

    Full Text Available Due to their very nature, ultrafast phenomena are often accompanied by the occurrence of nonadiabatic effects. From a theoretical perspective, the treatment of nonadiabatic processes makes it necessary to go beyond the (quasi static picture provided by the time-independent Schrödinger equation within the Born-Oppenheimer approximation and to find ways to tackle instead the full time-dependent electronic and nuclear quantum problem. In this review, we give an overview of different nonadiabatic processes that manifest themselves in electronic and nuclear dynamics ranging from the nonadiabatic phenomena taking place during tunnel ionization of atoms in strong laser fields to the radiationless relaxation through conical intersections and the nonadiabatic coupling of vibrational modes and discuss the computational approaches that have been developed to describe such phenomena. These methods range from the full solution of the combined nuclear-electronic quantum problem to a hierarchy of semiclassical approaches and even purely classical frameworks. The power of these simulation tools is illustrated by representative applications and the direct confrontation with experimental measurements performed in the National Centre of Competence for Molecular Ultrafast Science and Technology.

  7. Matching-pursuit/split-operator Fourier-transform simulations of nonadiabatic quantum dynamics

    Science.gov (United States)

    Wu, Yinghua; Herman, Michael F.; Batista, Victor S.

    2005-03-01

    A rigorous and practical approach for simulations of nonadiabatic quantum dynamics is introduced. The algorithm involves a natural extension of the matching-pursuit/split-operator Fourier-transform (MP/SOFT) method [Y. Wu and V. S. Batista, J. Chem. Phys. 121, 1676 (2004)] recently developed for simulations of adiabatic quantum dynamics in multidimensional systems. The MP/SOFT propagation scheme, extended to nonadiabatic dynamics, recursively applies the time-evolution operator as defined by the standard perturbation expansion to first-, or second-order, accuracy. The expansion is implemented in dynamically adaptive coherent-state representations, generated by an approach that combines the matching-pursuit algorithm with a gradient-based optimization method. The accuracy and efficiency of the resulting propagation method are demonstrated as applied to the canonical model systems introduced by Tully for testing simulations of dual curve-crossing nonadiabatic dynamics.

  8. Quantum chaos induced by nonadiabatic coupling in wave-packet dynamics

    International Nuclear Information System (INIS)

    Higuchi, Hisashi; Takatsuka, Kazuo

    2002-01-01

    The effect of nonadiabatic coupling due to breakdown of the Born-Oppenheimer approximation on chaos is investigated. A couple of measures (indicators) that detect the extent of chaos in wave-packet dynamics on coupled potential functions are devised. Using them, we show that chaos is indeed induced by a nonadiabatic coupling in individual time-dependent wave-packet dynamics. This chaos is genuinely of quantum nature, since it arises from bifurcation and merging of a wave packet at the quasicrossing region of two coupled potential functions

  9. Mode Specific Electronic Friction in Dissociative Chemisorption on Metal Surfaces: H2 on Ag(111)

    Science.gov (United States)

    Maurer, Reinhard J.; Jiang, Bin; Guo, Hua; Tully, John C.

    2017-06-01

    Electronic friction and the ensuing nonadiabatic energy loss play an important role in chemical reaction dynamics at metal surfaces. Using molecular dynamics with electronic friction evaluated on the fly from density functional theory, we find strong mode dependence and a dominance of nonadiabatic energy loss along the bond stretch coordinate for scattering and dissociative chemisorption of H2 on the Ag(111) surface. Exemplary trajectories with varying initial conditions indicate that this mode specificity translates into modulated energy loss during a dissociative chemisorption event. Despite minor nonadiabatic energy loss of about 5%, the directionality of friction forces induces dynamical steering that affects individual reaction outcomes, specifically for low-incidence energies and vibrationally excited molecules. Mode-specific friction induces enhanced loss of rovibrational rather than translational energy and will be most visible in its effect on final energy distributions in molecular scattering experiments.

  10. Sequential nonadiabatic excitation of large molecules and ions driven by strong laser fields

    International Nuclear Information System (INIS)

    Markevitch, Alexei N.; Levis, Robert J.; Romanov, Dmitri A.; Smith, Stanley M.; Schlegel, H. Bernhard; Ivanov, Misha Yu.

    2004-01-01

    Electronic processes leading to dissociative ionization of polyatomic molecules in strong laser fields are investigated experimentally, theoretically, and numerically. Using time-of-flight ion mass spectroscopy, we study the dependence of fragmentation on laser intensity for a series of related molecules and report regular trends in this dependence on the size, symmetry, and electronic structure of a molecule. Based on these data, we develop a model of dissociative ionization of polyatomic molecules in intense laser fields. The model is built on three elements: (i) nonadiabatic population transfer from the ground electronic state to the excited-state manifold via a doorway (charge-transfer) transition; (ii) exponential enhancement of this transition by collective dynamic polarization of all electrons, and (iii) sequential energy deposition in both neutral molecules and resulting molecular ions. The sequential nonadiabatic excitation is accelerated by a counterintuitive increase of a large molecule's polarizability following its ionization. The generic theory of sequential nonadiabatic excitation forms a basis for quantitative description of various nonlinear processes in polyatomic molecules and ions in strong laser fields

  11. Non-Adiabatic Molecular Dynamics Methods for Materials Discovery

    Energy Technology Data Exchange (ETDEWEB)

    Furche, Filipp [Univ. of California, Irvine, CA (United States); Parker, Shane M. [Univ. of California, Irvine, CA (United States); Muuronen, Mikko J. [Univ. of California, Irvine, CA (United States); Roy, Saswata [Univ. of California, Irvine, CA (United States)

    2017-04-04

    The flow of radiative energy in light-driven materials such as photosensitizer dyes or photocatalysts is governed by non-adiabatic transitions between electronic states and cannot be described within the Born-Oppenheimer approximation commonly used in electronic structure theory. The non-adiabatic molecular dynamics (NAMD) methods based on Tully surface hopping and time-dependent density functional theory developed in this project have greatly extended the range of molecular materials that can be tackled by NAMD simulations. New algorithms to compute molecular excited state and response properties efficiently were developed. Fundamental limitations of common non-linear response methods were discovered and characterized. Methods for accurate computations of vibronic spectra of materials such as black absorbers were developed and applied. It was shown that open-shell TDDFT methods capture bond breaking in NAMD simulations, a longstanding challenge for single-reference molecular dynamics simulations. The methods developed in this project were applied to study the photodissociation of acetaldehyde and revealed that non-adiabatic effects are experimentally observable in fragment kinetic energy distributions. Finally, the project enabled the first detailed NAMD simulations of photocatalytic water oxidation by titania nanoclusters, uncovering the mechanism of this fundamentally important reaction for fuel generation and storage.

  12. Recent Advances and Perspectives on Nonadiabatic Mixed Quantum-Classical Dynamics.

    Science.gov (United States)

    Crespo-Otero, Rachel; Barbatti, Mario

    2018-05-16

    Nonadiabatic mixed quantum-classical (NA-MQC) dynamics methods form a class of computational theoretical approaches in quantum chemistry tailored to investigate the time evolution of nonadiabatic phenomena in molecules and supramolecular assemblies. NA-MQC is characterized by a partition of the molecular system into two subsystems: one to be treated quantum mechanically (usually but not restricted to electrons) and another to be dealt with classically (nuclei). The two subsystems are connected through nonadiabatic couplings terms to enforce self-consistency. A local approximation underlies the classical subsystem, implying that direct dynamics can be simulated, without needing precomputed potential energy surfaces. The NA-MQC split allows reducing computational costs, enabling the treatment of realistic molecular systems in diverse fields. Starting from the three most well-established methods-mean-field Ehrenfest, trajectory surface hopping, and multiple spawning-this review focuses on the NA-MQC dynamics methods and programs developed in the last 10 years. It stresses the relations between approaches and their domains of application. The electronic structure methods most commonly used together with NA-MQC dynamics are reviewed as well. The accuracy and precision of NA-MQC simulations are critically discussed, and general guidelines to choose an adequate method for each application are delivered.

  13. Trajectory-based nonadiabatic dynamics with time-dependent density functional theory.

    Science.gov (United States)

    Curchod, Basile F E; Rothlisberger, Ursula; Tavernelli, Ivano

    2013-05-10

    Understanding the fate of an electronically excited molecule constitutes an important task for theoretical chemistry, and practical implications range from the interpretation of atto- and femtosecond spectroscopy to the development of light-driven molecular machines, the control of photochemical reactions, and the possibility of capturing sunlight energy. However, many challenging conceptual and technical problems are involved in the description of these phenomena such as 1) the failure of the well-known Born-Oppenheimer approximation; 2) the need for accurate electronic properties such as potential energy surfaces, excited nuclear forces, or nonadiabatic coupling terms; and 3) the necessity of describing the dynamics of the photoexcited nuclear wavepacket. This review provides an overview of the current methods to address points 1) and 3) and shows how time-dependent density functional theory (TDDFT) and its linear-response extension can be used for point 2). First, the derivation of Ehrenfest dynamics and nonadiabatic Bohmian dynamics is discussed and linked to Tully's trajectory surface hopping. Second, the coupling of these trajectory-based nonadiabatic schemes with TDDFT is described in detail with special emphasis on the derivation of the required electronic structure properties. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Nonadiabatic dynamics in intense continuous wave laser fields and real-time observation of the associated wavepacket bifurcation in terms of spectrogram of induced photon emission.

    Science.gov (United States)

    Mizuno, Yuta; Arasaki, Yasuki; Takatsuka, Kazuo

    2016-11-14

    We propose a theoretical principle to directly monitor the bifurcation of quantum wavepackets passing through nonadiabatic regions of a molecule that is placed in intense continuous wave (CW) laser fields. This idea makes use of the phenomenon of laser-driven photon emission from molecules that can undergo nonadiabatic transitions between ionic and covalent potential energy surfaces like Li + F - and LiF. The resultant photon emission spectra are of anomalous yet characteristic frequency and intensity, if pumped to an energy level in which the nonadiabatic region is accessible and placed in a CW laser field. The proposed method is designed to take the time-frequency spectrogram with an appropriate time-window from this photon emission to detect the time evolution of the frequency and intensity, which depends on the dynamics and location of the relevant nuclear wavepackets. This method is specifically designed for the study of dynamics in intense CW laser fields and is rather limited in scope than other techniques for femtosecond chemical dynamics in vacuum. The following characteristic features of dynamics can be mapped onto the spectrogram: (1) the period of driven vibrational motion (temporally confined vibrational states in otherwise dissociative channels, the period and other states of which dramatically vary depending on the CW driving lasers applied), (2) the existence of multiple nuclear wavepackets running individually on the field-dressed potential energy surfaces, (3) the time scale of coherent interaction between the nuclear wavepackets running on ionic and covalent electronic states after their branching (the so-called coherence time in the terminology of the theory of nonadiabatic interaction), and so on.

  15. Nonadiabatic excited-state molecular dynamics: On-the-fly limiting of essential excited states

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Tammie [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Naumov, Artem [Skolkovo Institute of Science and Technology, Moscow 143026 (Russian Federation); Fernandez-Alberti, Sebastian [Universidad Nacional de Quilmes, Roque Saenz Pea 352, B1876BXD Bernal (Argentina); Tretiak, Sergei, E-mail: serg@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2016-12-20

    The simulation of nonadiabatic dynamics in extended molecular systems involving hundreds of atoms and large densities of states is particularly challenging. Nonadiabatic coupling terms (NACTs) represent a significant numerical bottleneck in surface hopping approaches. Rather than using unreliable NACT cutting schemes, here we develop “on-the-fly” state limiting methods to eliminate states that are no longer essential for the non-radiative relaxation dynamics as a trajectory proceeds. We propose a state number criteria and an energy-based state limit. The latter is more physically relevant by requiring a user-imposed energy threshold. For this purpose, we introduce a local kinetic energy gauge by summing contributions from atoms within the spatial localization of the electronic wavefunction to define the energy available for upward hops. The proposed state limiting schemes are implemented within the nonadiabatic excited-state molecular dynamics framework to simulate photoinduced relaxation in poly-phenylene vinylene (PPV) and branched poly-phenylene ethynylene (PPE) oligomers for benchmark evaluation.

  16. An On-the-Fly Surface-Hopping Program JADE for Nonadiabatic Molecular Dynamics of Polyatomic Systems: Implementation and Applications.

    Science.gov (United States)

    Du, Likai; Lan, Zhenggang

    2015-04-14

    Nonadiabatic dynamics simulations have rapidly become an indispensable tool for understanding ultrafast photochemical processes in complex systems. Here, we present our recently developed on-the-fly nonadiabatic dynamics package, JADE, which allows researchers to perform nonadiabatic excited-state dynamics simulations of polyatomic systems at an all-atomic level. The nonadiabatic dynamics is based on Tully's surface-hopping approach. Currently, several electronic structure methods (CIS, TDHF, TDDFT(RPA/TDA), and ADC(2)) are supported, especially TDDFT, aiming at performing nonadiabatic dynamics on medium- to large-sized molecules. The JADE package has been interfaced with several quantum chemistry codes, including Turbomole, Gaussian, and Gamess (US). To consider environmental effects, the Langevin dynamics was introduced as an easy-to-use scheme into the standard surface-hopping dynamics. The JADE package is mainly written in Fortran for greater numerical performance and Python for flexible interface construction, with the intent of providing open-source, easy-to-use, well-modularized, and intuitive software in the field of simulations of photochemical and photophysical processes. To illustrate the possible applications of the JADE package, we present a few applications of excited-state dynamics for various polyatomic systems, such as the methaniminium cation, fullerene (C20), p-dimethylaminobenzonitrile (DMABN) and its primary amino derivative aminobenzonitrile (ABN), and 10-hydroxybenzo[h]quinoline (10-HBQ).

  17. Nonadiabatic dynamics with intersystem crossings: A time-dependent density functional theory implementation

    Energy Technology Data Exchange (ETDEWEB)

    Franco de Carvalho, F. [Centre Européen de Calcul Atomique et Moléculaire, Ecole Polytechnique Fédérale de Lausanne, Lausanne (Switzerland); Tavernelli, I. [IBM Research GmbH, Zurich Research Laboratory, 8803 Ruschlikon (Switzerland)

    2015-12-14

    In this work, we derive a method to perform trajectory-based nonadiabatic dynamics that is able to describe both nonadiabatic transitions and intersystem crossing events (transitions between states of different spin-multiplicity) at the same level of theory, namely, time-dependent density functional theory (TDDFT). To this end, we combined our previously developed TDDFT-based trajectory surface hopping scheme with an accurate and efficient algorithm for the calculation of the spin-orbit coupling (SOC) matrix elements. More specifically, we designed two algorithms for the calculation of intersystem crossing transitions, one based on an extended Tully’s surface hopping scheme including SOC and the second based on a Landau-Zener approximation applied to the spin sector of the electronic Hilbert space. This development allows for the design of an efficient on-the-fly nonadiabatic approach that can handle, on an equal footing, nonadiabatic and intersystem crossing transitions. The method is applied to the study of the photophysics of sulfur dioxide (SO{sub 2}) in gas and liquid phases.

  18. Semiclassical Monte Carlo: A first principles approach to non-adiabatic molecular dynamics

    International Nuclear Information System (INIS)

    White, Alexander J.; Gorshkov, Vyacheslav N.; Wang, Ruixi; Tretiak, Sergei; Mozyrsky, Dmitry

    2014-01-01

    Modeling the dynamics of photophysical and (photo)chemical reactions in extended molecular systems is a new frontier for quantum chemistry. Many dynamical phenomena, such as intersystem crossing, non-radiative relaxation, and charge and energy transfer, require a non-adiabatic description which incorporate transitions between electronic states. Additionally, these dynamics are often highly sensitive to quantum coherences and interference effects. Several methods exist to simulate non-adiabatic dynamics; however, they are typically either too expensive to be applied to large molecular systems (10's-100's of atoms), or they are based on ad hoc schemes which may include severe approximations due to inconsistencies in classical and quantum mechanics. We present, in detail, an algorithm based on Monte Carlo sampling of the semiclassical time-dependent wavefunction that involves running simple surface hopping dynamics, followed by a post-processing step which adds little cost. The method requires only a few quantities from quantum chemistry calculations, can systematically be improved, and provides excellent agreement with exact quantum mechanical results. Here we show excellent agreement with exact solutions for scattering results of standard test problems. Additionally, we find that convergence of the wavefunction is controlled by complex valued phase factors, the size of the non-adiabatic coupling region, and the choice of sampling function. These results help in determining the range of applicability of the method, and provide a starting point for further improvement

  19. Nonadiabatic Ponderomotive Potentials

    International Nuclear Information System (INIS)

    Dodin IY, Fisch NJ

    2005-01-01

    An approximate integral of the Manley-Rowe type is found for a particle moving in a high-frequency field, which may interact resonantly with natural particle oscillations. An effective ponderomotive potential is introduced accordingly and can capture nonadiabatic particle dynamics. We show that nonadiabatic ponderomotive barriers can trap classical particles, produce cooling effect, and generate one-way walls for resonant species. Possible atomic applications are also envisioned

  20. DFTBaby: A software package for non-adiabatic molecular dynamics simulations based on long-range corrected tight-binding TD-DFT(B)

    Science.gov (United States)

    Humeniuk, Alexander; Mitrić, Roland

    2017-12-01

    A software package, called DFTBaby, is published, which provides the electronic structure needed for running non-adiabatic molecular dynamics simulations at the level of tight-binding DFT. A long-range correction is incorporated to avoid spurious charge transfer states. Excited state energies, their analytic gradients and scalar non-adiabatic couplings are computed using tight-binding TD-DFT. These quantities are fed into a molecular dynamics code, which integrates Newton's equations of motion for the nuclei together with the electronic Schrödinger equation. Non-adiabatic effects are included by surface hopping. As an example, the program is applied to the optimization of excited states and non-adiabatic dynamics of polyfluorene. The python and Fortran source code is available at http://www.dftbaby.chemie.uni-wuerzburg.de.

  1. Ab initio multiple cloning algorithm for quantum nonadiabatic molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Makhov, Dmitry V.; Shalashilin, Dmitrii V. [Department of Chemistry, University of Leeds, Leeds LS2 9JT (United Kingdom); Glover, William J.; Martinez, Todd J. [Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, USA and SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

    2014-08-07

    We present a new algorithm for ab initio quantum nonadiabatic molecular dynamics that combines the best features of ab initio Multiple Spawning (AIMS) and Multiconfigurational Ehrenfest (MCE) methods. In this new method, ab initio multiple cloning (AIMC), the individual trajectory basis functions (TBFs) follow Ehrenfest equations of motion (as in MCE). However, the basis set is expanded (as in AIMS) when these TBFs become sufficiently mixed, preventing prolonged evolution on an averaged potential energy surface. We refer to the expansion of the basis set as “cloning,” in analogy to the “spawning” procedure in AIMS. This synthesis of AIMS and MCE allows us to leverage the benefits of mean-field evolution during periods of strong nonadiabatic coupling while simultaneously avoiding mean-field artifacts in Ehrenfest dynamics. We explore the use of time-displaced basis sets, “trains,” as a means of expanding the basis set for little cost. We also introduce a new bra-ket averaged Taylor expansion (BAT) to approximate the necessary potential energy and nonadiabatic coupling matrix elements. The BAT approximation avoids the necessity of computing electronic structure information at intermediate points between TBFs, as is usually done in saddle-point approximations used in AIMS. The efficiency of AIMC is demonstrated on the nonradiative decay of the first excited state of ethylene. The AIMC method has been implemented within the AIMS-MOLPRO package, which was extended to include Ehrenfest basis functions.

  2. Path-integral isomorphic Hamiltonian for including nuclear quantum effects in non-adiabatic dynamics

    Science.gov (United States)

    Tao, Xuecheng; Shushkov, Philip; Miller, Thomas F.

    2018-03-01

    We describe a path-integral approach for including nuclear quantum effects in non-adiabatic chemical dynamics simulations. For a general physical system with multiple electronic energy levels, a corresponding isomorphic Hamiltonian is introduced such that Boltzmann sampling of the isomorphic Hamiltonian with classical nuclear degrees of freedom yields the exact quantum Boltzmann distribution for the original physical system. In the limit of a single electronic energy level, the isomorphic Hamiltonian reduces to the familiar cases of either ring polymer molecular dynamics (RPMD) or centroid molecular dynamics Hamiltonians, depending on the implementation. An advantage of the isomorphic Hamiltonian is that it can easily be combined with existing mixed quantum-classical dynamics methods, such as surface hopping or Ehrenfest dynamics, to enable the simulation of electronically non-adiabatic processes with nuclear quantum effects. We present numerical applications of the isomorphic Hamiltonian to model two- and three-level systems, with encouraging results that include improvement upon a previously reported combination of RPMD with surface hopping in the deep-tunneling regime.

  3. Multiple coupled landscapes and non-adiabatic dynamics with applications to self-activating genes.

    Science.gov (United States)

    Chen, Cong; Zhang, Kun; Feng, Haidong; Sasai, Masaki; Wang, Jin

    2015-11-21

    Many physical, chemical and biochemical systems (e.g. electronic dynamics and gene regulatory networks) are governed by continuous stochastic processes (e.g. electron dynamics on a particular electronic energy surface and protein (gene product) synthesis) coupled with discrete processes (e.g. hopping among different electronic energy surfaces and on and off switching of genes). One can also think of the underlying dynamics as the continuous motion on a particular landscape and discrete hoppings among different landscapes. The main difference of such systems from the intra-landscape dynamics alone is the emergence of the timescale involved in transitions among different landscapes in addition to the timescale involved in a particular landscape. The adiabatic limit when inter-landscape hoppings are fast compared to continuous intra-landscape dynamics has been studied both analytically and numerically, but the analytical treatment of the non-adiabatic regime where the inter-landscape hoppings are slow or comparable to continuous intra-landscape dynamics remains challenging. In this study, we show that there exists mathematical mapping of the dynamics on 2(N) discretely coupled N continuous dimensional landscapes onto one single landscape in 2N dimensional extended continuous space. On this 2N dimensional landscape, eddy current emerges as a sign of non-equilibrium non-adiabatic dynamics and plays an important role in system evolution. Many interesting physical effects such as the enhancement of fluctuations, irreversibility, dissipation and optimal kinetics emerge due to non-adiabaticity manifested by the eddy current illustrated for an N = 1 self-activator. We further generalize our theory to the N-gene network with multiple binding sites and multiple synthesis rates for discretely coupled non-equilibrium stochastic physical and biological systems.

  4. Between ethylene and polyenes--the non-adiabatic dynamics of cis-dienes

    DEFF Research Database (Denmark)

    Kuhlman, Thomas Scheby; Glover, William J; Mori, Toshifumi

    2012-01-01

    Using Ab Initio Multiple Spawning (AIMS) with a Multi-State Multi-Reference Perturbation theory (MS-MR-CASPT2) treatment of the electronic structure, we have simulated the non-adiabatic excited state dynamics of cyclopentadiene (CPD) and 1,2,3,4-tetramethyl-cyclopentadiene (Me4-CPD) following exc...

  5. Nodeless vibrational amplitudes and quantum nonadiabatic dynamics in the nested funnel for a pseudo Jahn-Teller molecule or homodimer

    Science.gov (United States)

    Peters, William K.; Tiwari, Vivek; Jonas, David M.

    2017-11-01

    The nonadiabatic states and dynamics are investigated for a linear vibronic coupling Hamiltonian with a static electronic splitting and weak off-diagonal Jahn-Teller coupling through a single vibration with a vibrational-electronic resonance. With a transformation of the electronic basis, this Hamiltonian is also applicable to the anti-correlated vibration in a symmetric homodimer with marginally strong constant off-diagonal coupling, where the non-adiabatic states and dynamics model electronic excitation energy transfer or self-exchange electron transfer. For parameters modeling a free-base naphthalocyanine, the nonadiabatic couplings are deeply quantum mechanical and depend on wavepacket width; scalar couplings are as important as the derivative couplings that are usually interpreted to depend on vibrational velocity in semiclassical curve crossing or surface hopping theories. A colored visualization scheme that fully characterizes the non-adiabatic states using the exact factorization is developed. The nonadiabatic states in this nested funnel have nodeless vibrational factors with strongly avoided zeroes in their vibrational probability densities. Vibronic dynamics are visualized through the vibrational coordinate dependent density of the time-dependent dipole moment in free induction decay. Vibrational motion is amplified by the nonadiabatic couplings, with asymmetric and anisotropic motions that depend upon the excitation polarization in the molecular frame and can be reversed by a change in polarization. This generates a vibrational quantum beat anisotropy in excess of 2/5. The amplitude of vibrational motion can be larger than that on the uncoupled potentials, and the electronic population transfer is maximized within one vibrational period. Most of these dynamics are missed by the adiabatic approximation, and some electronic and vibrational motions are completely suppressed by the Condon approximation of a coordinate-independent transition dipole between

  6. Non-adiabatic molecular dynamic simulations of opening reaction of molecular junctions

    Czech Academy of Sciences Publication Activity Database

    Zobač, Vladimír; Lewis, J.P.; Jelínek, Pavel

    2016-01-01

    Roč. 27, č. 28 (2016), 1-8, č. článku 285202. ISSN 0957-4484 R&D Projects: GA ČR(CZ) GA14-02079S Institutional support: RVO:68378271 Keywords : non-adiabatic molecular dynamics * molecular junctions * molecular switches * DFT Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.440, year: 2016

  7. Quantum-classical correspondence in steady states of nonadiabatic systems

    International Nuclear Information System (INIS)

    Fujii, Mikiya; Yamashita, Koichi

    2015-01-01

    We first present nonadiabatic path integral which is exact formulation of quantum dynamics in nonadiabatic systems. Then, by applying the stationary phase approximations to the nonadiabatic path integral, a semiclassical quantization condition, i.e., quantum-classical correspondence, for steady states of nonadiabatic systems is presented as a nonadiabatic trace formula. The present quantum-classical correspondence indicates that a set of primitive hopping periodic orbits, which are invariant under time evolution in the phase space of the slow degree of freedom, should be quantized. The semiclassical quantization is then applied to a simple nonadiabatic model and accurately reproduces exact quantum energy levels

  8. Semiclassical quantization of nonadiabatic systems with hopping periodic orbits

    International Nuclear Information System (INIS)

    Fujii, Mikiya; Yamashita, Koichi

    2015-01-01

    We present a semiclassical quantization condition, i.e., quantum–classical correspondence, for steady states of nonadiabatic systems consisting of fast and slow degrees of freedom (DOFs) by extending Gutzwiller’s trace formula to a nonadiabatic form. The quantum–classical correspondence indicates that a set of primitive hopping periodic orbits, which are invariant under time evolution in the phase space of the slow DOF, should be quantized. The semiclassical quantization is then applied to a simple nonadiabatic model and accurately reproduces exact quantum energy levels. In addition to the semiclassical quantization condition, we also discuss chaotic dynamics involved in the classical limit of nonadiabatic dynamics

  9. TREATMENT OF NONADIABATIC TRANSITIONS BY DENSITY-MATRIX EVOLUTION AND MOLECULAR-DYNAMICS SIMULATIONS

    NARCIS (Netherlands)

    MAVRI, J; BERENDSEN, HJC

    1994-01-01

    A density matrix evolution (DME) method (H.J.C. Berendsen and J. Mavri, J. Phys. Chem., 97 (1993) 13469) to simulate the dynamics of quantum systems embedded in a classical environment is presented. The DME method allows treatment of nonadiabatic transitions. As numerical examples the collinear

  10. Variational nonadiabatic dynamics in the moving crude adiabatic representation: Further merging of nuclear dynamics and electronic structure

    Science.gov (United States)

    Joubert-Doriol, Loïc; Izmaylov, Artur F.

    2018-03-01

    A new methodology of simulating nonadiabatic dynamics using frozen-width Gaussian wavepackets within the moving crude adiabatic representation with the on-the-fly evaluation of electronic structure is presented. The main feature of the new approach is the elimination of any global or local model representation of electronic potential energy surfaces; instead, the electron-nuclear interaction is treated explicitly using the Gaussian integration. As a result, the new scheme does not introduce any uncontrolled approximations. The employed variational principle ensures the energy conservation and leaves the number of electronic and nuclear basis functions as the only parameter determining the accuracy. To assess performance of the approach, a model with two electronic and two nuclear spacial degrees of freedom containing conical intersections between potential energy surfaces has been considered. Dynamical features associated with nonadiabatic transitions and nontrivial geometric (or Berry) phases were successfully reproduced within a limited basis expansion.

  11. Semiclassical theory of electronically nonadiabatic chemical dynamics: Incorporation of the Zhu-Nakamura theory into the frozen Gaussian propagation method

    International Nuclear Information System (INIS)

    Kondorskiy, A.; Nakamura, H.

    2004-01-01

    The title theory is developed by combining the Herman-Kluk semiclassical theory for adiabatic propagation on single potential-energy surface and the semiclassical Zhu-Nakamura theory for nonadiabatic transition. The formulation with use of natural mathematical principles leads to a quite simple expression for the propagator based on classical trajectories and simple formulas are derived for overall adiabatic and nonadiabatic processes. The theory is applied to electronically nonadiabatic photodissociation processes: a one-dimensional problem of H 2 + in a cw (continuous wave) laser field and a two-dimensional model problem of H 2 O in a cw laser field. The theory is found to work well for the propagation duration of several molecular vibrational periods and wide energy range. Although the formulation is made for the case of laser induced nonadiabatic processes, it is straightforwardly applicable to ordinary electronically nonadiabatic chemical dynamics

  12. Memory effects in nonadiabatic molecular dynamics at metal surfaces

    DEFF Research Database (Denmark)

    Olsen, Thomas; Schiøtz, Jakob

    2010-01-01

    We study the effect of temporal correlation in a Langevin equation describing nonadiabatic dynamics at metal surfaces. For a harmonic oscillator, the Langevin equation preserves the quantum dynamics exactly and it is demonstrated that memory effects are needed in order to conserve the ground state...... energy of the oscillator. We then compare the result of Langevin dynamics in a harmonic potential with a perturbative master equation approach and show that the Langevin equation gives a better description in the nonperturbative range of high temperatures and large friction. Unlike the master equation......, this approach is readily extended to anharmonic potentials. Using density functional theory, we calculate representative Langevin trajectories for associative desorption of N-2 from Ru(0001) and find that memory effects lower the dissipation of energy. Finally, we propose an ab initio scheme to calculate...

  13. Non-adiabatic molecular dynamics with complex quantum trajectories. I. The diabatic representation.

    Science.gov (United States)

    Zamstein, Noa; Tannor, David J

    2012-12-14

    We extend a recently developed quantum trajectory method [Y. Goldfarb, I. Degani, and D. J. Tannor, J. Chem. Phys. 125, 231103 (2006)] to treat non-adiabatic transitions. Each trajectory evolves on a single surface according to Newton's laws with complex positions and momenta. The transfer of amplitude between surfaces stems naturally from the equations of motion, without the need for surface hopping. In this paper we derive the equations of motion and show results in the diabatic representation, which is rarely used in trajectory methods for calculating non-adiabatic dynamics. We apply our method to the first two benchmark models introduced by Tully [J. Chem. Phys. 93, 1061 (1990)]. Besides giving the probability branching ratios between the surfaces, the method also allows the reconstruction of the time-dependent wavepacket. Our results are in quantitative agreement with converged quantum mechanical calculations.

  14. Semiclassical modelling of finite-pulse effects on non-adiabatic photodynamics via initial condition filtering: The predissociation of NaI as a test case

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Mesa, Aliezer [Departmento de Física Teórica, Universidad de la Habana, San Lázaro y L, La Habana 10400 (Cuba); Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, D-14476 Potsdam-Golm (Germany); Saalfrank, Peter [Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, D-14476 Potsdam-Golm (Germany)

    2015-05-21

    Femtosecond-laser pulse driven non-adiabatic spectroscopy and dynamics in molecular and condensed phase systems continue to be a challenge for theoretical modelling. One of the main obstacles is the “curse of dimensionality” encountered in non-adiabatic, exact wavepacket propagation. A possible route towards treating complex molecular systems is via semiclassical surface-hopping schemes, in particular if they account not only for non-adiabatic post-excitation dynamics but also for the initial optical excitation. One such approach, based on initial condition filtering, will be put forward in what follows. As a simple test case which can be compared with exact wavepacket dynamics, we investigate the influence of the different parameters determining the shape of a laser pulse (e.g., its finite width and a possible chirp) on the predissociation dynamics of a NaI molecule, upon photoexcitation of the A(0{sup +}) state. The finite-pulse effects are mapped into the initial conditions for semiclassical surface-hopping simulations. The simulated surface-hopping diabatic populations are in qualitative agreement with the quantum mechanical results, especially concerning the subpicosend photoinduced dynamics, the main deviations being the relative delay of the non-adiabatic transitions in the semiclassical picture. Likewise, these differences in the time-dependent electronic populations calculated via the semiclassical and the quantum methods are found to have a mild influence on the overall probability density distribution. As a result, the branching ratios between the bound and the dissociative reaction channels and the time-evolution of the molecular wavepacket predicted by the semiclassical method agree with those computed using quantum wavepacket propagation. Implications for more challenging molecular systems are given.

  15. Signatures of non-adiabatic dynamics in the fine-structure state distributions of the OH(X~/A~) products in the B-band photodissociation of H2O

    International Nuclear Information System (INIS)

    Zhou, Linsen; Xie, Daiqian; Guo, Hua

    2015-01-01

    A detailed quantum mechanical characterization of the photodissociation dynamics of H 2 O at 121.6 nm is presented. The calculations were performed using a full-dimensional wave packet method on coupled potential energy surfaces of all relevant electronic states. Our state-to-state model permits a detailed analysis of the OH(X ~ /A ~ ) product fine-structure populations as a probe of the non-adiabatic dissociation dynamics. The calculated rotational state distributions of the two Λ-doublet levels of OH(X ~ , v = 0) exhibit very different characteristics. The A′ states, produced mostly via the B ~ →X ~ conical intersection pathway, have significantly higher populations than the A″ counterparts, which are primarily from the B ~ →A ~ Renner-Teller pathway. The former features a highly inverted and oscillatory rotational state distribution, while the latter has a smooth distribution with much less rotational excitation. In good agreement with experiment, the calculated total OH(X ~ ) rotational state distribution and anisotropy parameters show clear even-odd oscillations, which can be attributed to a quantum mechanical interference between waves emanating from the HOH and HHO conical intersections in the B ~ →X ~ non-adiabatic pathway. On the other hand, the experiment-theory agreement for the OH(A ~ ) fragment is also satisfactory, although some small quantitative differences suggest remaining imperfections of the ab initio based potential energy surfaces

  16. Signatures of non-adiabatic dynamics in the fine-structure state distributions of the OH(X̃/Ã) products in the B-band photodissociation of H2O.

    Science.gov (United States)

    Zhou, Linsen; Xie, Daiqian; Guo, Hua

    2015-03-28

    A detailed quantum mechanical characterization of the photodissociation dynamics of H2O at 121.6 nm is presented. The calculations were performed using a full-dimensional wave packet method on coupled potential energy surfaces of all relevant electronic states. Our state-to-state model permits a detailed analysis of the OH(X̃/Ã) product fine-structure populations as a probe of the non-adiabatic dissociation dynamics. The calculated rotational state distributions of the two Λ-doublet levels of OH(X̃, v = 0) exhibit very different characteristics. The A' states, produced mostly via the B̃→X̃ conical intersection pathway, have significantly higher populations than the A″ counterparts, which are primarily from the B̃→Ã Renner-Teller pathway. The former features a highly inverted and oscillatory rotational state distribution, while the latter has a smooth distribution with much less rotational excitation. In good agreement with experiment, the calculated total OH(X̃) rotational state distribution and anisotropy parameters show clear even-odd oscillations, which can be attributed to a quantum mechanical interference between waves emanating from the HOH and HHO conical intersections in the B̃→X̃ non-adiabatic pathway. On the other hand, the experiment-theory agreement for the OH(Ã) fragment is also satisfactory, although some small quantitative differences suggest remaining imperfections of the ab initio based potential energy surfaces.

  17. Strong-field dissociation dynamics

    International Nuclear Information System (INIS)

    DiMauro, L.F.; Yang, Baorui.

    1993-01-01

    The strong-field dissociation behavior of diatomic molecules is examined under two distinctive physical scenarios. In the first scenario, the dissociation of the isolated hydrogen and deuterium molecular ions is discussed. The dynamics of above-threshold dissociation (ATD) are investigated over a wide range of green and infrared intensities and compared to a dressed-state model. The second situation arises when strong-field neutral dissociation is followed by ionization of the atomic fragments. The study results in a direct measure of the atomic fragment's ac-Stark shift by observing the intensity-dependent shifts in the electron or nuclear fragment kinetic energy. 8 figs., 14 refs

  18. Dynamics of photoionization from molecular electronic wavepacket states in intense pulse laser fields: A nonadiabatic electron wavepacket study.

    Science.gov (United States)

    Matsuoka, Takahide; Takatsuka, Kazuo

    2017-04-07

    A theory for dynamics of molecular photoionization from nonadiabatic electron wavepackets driven by intense pulse lasers is proposed. Time evolution of photoelectron distribution is evaluated in terms of out-going electron flux (current of the probability density of electrons) that has kinetic energy high enough to recede from the molecular system. The relevant electron flux is in turn evaluated with the complex-valued electronic wavefunctions that are time evolved in nonadiabatic electron wavepacket dynamics in laser fields. To uniquely rebuild such wavefunctions with its electronic population being lost by ionization, we adopt the complex-valued natural orbitals emerging from the electron density as building blocks of the total wavefunction. The method has been implemented into a quantum chemistry code, which is based on configuration state mixing for polyatomic molecules. Some of the practical aspects needed for its application will be presented. As a first illustrative example, we show the results of hydrogen molecule and its isotope substitutes (HD and DD), which are photoionized by a two-cycle pulse laser. Photon emission spectrum associated with above threshold ionization is also shown. Another example is taken from photoionization dynamics from an excited state of a water molecule. Qualitatively significant effects of nonadiabatic interaction on the photoelectron spectrum are demonstrated.

  19. Accurate nonadiabatic quantum dynamics on the cheap: Making the most of mean field theory with master equations

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Aaron; Markland, Thomas E., E-mail: tmarkland@stanford.edu [Department of Chemistry, Stanford University, Stanford, California 94305 (United States); Brackbill, Nora [Department of Physics, Stanford University, Stanford, California 94305 (United States)

    2015-03-07

    In this article, we show how Ehrenfest mean field theory can be made both a more accurate and efficient method to treat nonadiabatic quantum dynamics by combining it with the generalized quantum master equation framework. The resulting mean field generalized quantum master equation (MF-GQME) approach is a non-perturbative and non-Markovian theory to treat open quantum systems without any restrictions on the form of the Hamiltonian that it can be applied to. By studying relaxation dynamics in a wide range of dynamical regimes, typical of charge and energy transfer, we show that MF-GQME provides a much higher accuracy than a direct application of mean field theory. In addition, these increases in accuracy are accompanied by computational speed-ups of between one and two orders of magnitude that become larger as the system becomes more nonadiabatic. This combination of quantum-classical theory and master equation techniques thus makes it possible to obtain the accuracy of much more computationally expensive approaches at a cost lower than even mean field dynamics, providing the ability to treat the quantum dynamics of atomistic condensed phase systems for long times.

  20. Accurate nonadiabatic quantum dynamics on the cheap: making the most of mean field theory with master equations.

    Science.gov (United States)

    Kelly, Aaron; Brackbill, Nora; Markland, Thomas E

    2015-03-07

    In this article, we show how Ehrenfest mean field theory can be made both a more accurate and efficient method to treat nonadiabatic quantum dynamics by combining it with the generalized quantum master equation framework. The resulting mean field generalized quantum master equation (MF-GQME) approach is a non-perturbative and non-Markovian theory to treat open quantum systems without any restrictions on the form of the Hamiltonian that it can be applied to. By studying relaxation dynamics in a wide range of dynamical regimes, typical of charge and energy transfer, we show that MF-GQME provides a much higher accuracy than a direct application of mean field theory. In addition, these increases in accuracy are accompanied by computational speed-ups of between one and two orders of magnitude that become larger as the system becomes more nonadiabatic. This combination of quantum-classical theory and master equation techniques thus makes it possible to obtain the accuracy of much more computationally expensive approaches at a cost lower than even mean field dynamics, providing the ability to treat the quantum dynamics of atomistic condensed phase systems for long times.

  1. Nonadiabatic ab initio molecular dynamics of photoisomerization reaction between 1,3-cyclohexadiene and 1,3,5-cis-hexatriene

    International Nuclear Information System (INIS)

    Ohta, Ayumi; Kobayashi, Osamu; Danielache, Sebastian O.; Nanbu, Shinkoh

    2015-01-01

    Highlights: • The photoisomerization between cyclohexadiene and hexatriene was simulated. • Nonadiabatic ab initio MD simulations were employed to elucidate the mechanism. • Each excitations to S_1 and S_2 were simulated using full-dimensional model. • Specific molecular motions at CoIns and molecular vibrations on S_1 PES were found. • The one-sided product branching ratio was obtained at the photoexcitation to S_2. - Abstract: The photoisomerization process between 1,3-cyclohexadiene (CHD) and 1,3,5-cis-hexatriene (HT) has been studied by nonadiabatic ab initio molecular dynamics based on trajectory surface-hopping approach with a full-dimensional reaction model. The quantum chemical calculations were treated at MS-MR-CASPT2 level for 8 electrons in 8 orbitals with the cc-pVDZ basis set. The Zhu–Nakamura formula was employed to evaluate nonadiabatic transition probabilities. S_1 and S_2 states were included in the photoisomerization dynamics. Lifetimes and CHD:HT branching ratios were computationally estimated on the basis of statistical analysis of multiple executed trajectories. The analysis of trajectories suggested that the nonadiabatic transitions at the S_0/S_1 and S_1/S_2 conical intersections (CoIn) are correlated to the Kekulé-type vibration and the C3–C4–C5 bending motion, respectively. The one-sided branching ratio was obtained by excitations to the S_2 state; 70:30. The critical branching process was found to be dominated by the location of CoIn in potential energy hypersurface of the excited state.

  2. Nonadiabatic holonomic quantum computation using Rydberg blockade

    Science.gov (United States)

    Kang, Yi-Hao; Chen, Ye-Hong; Shi, Zhi-Cheng; Huang, Bi-Hua; Song, Jie; Xia, Yan

    2018-04-01

    In this paper, we propose a scheme for realizing nonadiabatic holonomic computation assisted by two atoms and the shortcuts to adiabaticity (STA). The blockade effect induced by strong Rydberg-mediated interaction between two Rydberg atoms provides us the possibility to simplify the dynamics of the system, and the STA helps us design pulses for implementing the holonomic computation with high fidelity. Numerical simulations show the scheme is noise immune and decoherence resistant. Therefore, the current scheme may provide some useful perspectives for realizing nonadiabatic holonomic computation.

  3. Enhanced Nonadiabaticity in Vortex Cores due to the Emergent Hall Effect

    KAUST Repository

    Bisig, André

    2017-01-04

    We present a combined theoretical and experimental study, investigating the origin of the enhanced nonadiabaticity of magnetic vortex cores. Scanning transmission x-ray microscopy is used to image the vortex core gyration dynamically to measure the nonadiabaticity with high precision, including a high confidence upper bound. We show theoretically, that the large nonadiabaticity parameter observed experimentally can be explained by the presence of local spin currents arising from a texture induced emergent Hall effect. This study demonstrates that the magnetic damping α and nonadiabaticity parameter β are very sensitive to the topology of the magnetic textures, resulting in an enhanced ratio (β/α>1) in magnetic vortex cores or Skyrmions.

  4. Enhanced Nonadiabaticity in Vortex Cores due to the Emergent Hall Effect

    KAUST Repository

    Bisig, André ; Akosa, Collins Ashu; Moon, Jung-Hwan; Rhensius, Jan; Moutafis, Christoforos; von Bieren, Arndt; Heidler, Jakoba; Kiliani, Gillian; Kammerer, Matthias; Curcic, Michael; Weigand, Markus; Tyliszczak, Tolek; Van Waeyenberge, Bartel; Stoll, Hermann; Schü tz, Gisela; Lee, Kyung-Jin; Manchon, Aurelien; Klä ui, Mathias

    2017-01-01

    We present a combined theoretical and experimental study, investigating the origin of the enhanced nonadiabaticity of magnetic vortex cores. Scanning transmission x-ray microscopy is used to image the vortex core gyration dynamically to measure the nonadiabaticity with high precision, including a high confidence upper bound. We show theoretically, that the large nonadiabaticity parameter observed experimentally can be explained by the presence of local spin currents arising from a texture induced emergent Hall effect. This study demonstrates that the magnetic damping α and nonadiabaticity parameter β are very sensitive to the topology of the magnetic textures, resulting in an enhanced ratio (β/α>1) in magnetic vortex cores or Skyrmions.

  5. Signatures of non-adiabatic dynamics in the fine-structure state distributions of the OH( X ˜ / A ˜ ) products in the B-band photodissociation of H2O

    Science.gov (United States)

    Zhou, Linsen; Xie, Daiqian; Guo, Hua

    2015-03-01

    A detailed quantum mechanical characterization of the photodissociation dynamics of H2O at 121.6 nm is presented. The calculations were performed using a full-dimensional wave packet method on coupled potential energy surfaces of all relevant electronic states. Our state-to-state model permits a detailed analysis of the OH( X ˜ / A ˜ ) product fine-structure populations as a probe of the non-adiabatic dissociation dynamics. The calculated rotational state distributions of the two Λ-doublet levels of OH( X ˜ , v = 0) exhibit very different characteristics. The A' states, produced mostly via the B ˜ → X ˜ conical intersection pathway, have significantly higher populations than the A″ counterparts, which are primarily from the B ˜ → A ˜ Renner-Teller pathway. The former features a highly inverted and oscillatory rotational state distribution, while the latter has a smooth distribution with much less rotational excitation. In good agreement with experiment, the calculated total OH( X ˜ ) rotational state distribution and anisotropy parameters show clear even-odd oscillations, which can be attributed to a quantum mechanical interference between waves emanating from the HOH and HHO conical intersections in the B ˜ → X ˜ non-adiabatic pathway. On the other hand, the experiment-theory agreement for the OH( A ˜ ) fragment is also satisfactory, although some small quantitative differences suggest remaining imperfections of the ab initio based potential energy surfaces.

  6. Signatures of non-adiabatic dynamics in the fine-structure state distributions of the OH(X{sup ~}/A{sup ~}) products in the B-band photodissociation of H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Linsen [Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210093 (China); Xie, Daiqian, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210093 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Guo, Hua, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2015-03-28

    A detailed quantum mechanical characterization of the photodissociation dynamics of H{sub 2}O at 121.6 nm is presented. The calculations were performed using a full-dimensional wave packet method on coupled potential energy surfaces of all relevant electronic states. Our state-to-state model permits a detailed analysis of the OH(X{sup ~}/A{sup ~}) product fine-structure populations as a probe of the non-adiabatic dissociation dynamics. The calculated rotational state distributions of the two Λ-doublet levels of OH(X{sup ~}, v = 0) exhibit very different characteristics. The A′ states, produced mostly via the B{sup ~}→X{sup ~} conical intersection pathway, have significantly higher populations than the A″ counterparts, which are primarily from the B{sup ~}→A{sup ~} Renner-Teller pathway. The former features a highly inverted and oscillatory rotational state distribution, while the latter has a smooth distribution with much less rotational excitation. In good agreement with experiment, the calculated total OH(X{sup ~}) rotational state distribution and anisotropy parameters show clear even-odd oscillations, which can be attributed to a quantum mechanical interference between waves emanating from the HOH and HHO conical intersections in the B{sup ~}→X{sup ~} non-adiabatic pathway. On the other hand, the experiment-theory agreement for the OH(A{sup ~}) fragment is also satisfactory, although some small quantitative differences suggest remaining imperfections of the ab initio based potential energy surfaces.

  7. Excited state non-adiabatic dynamics of the smallest polyene, trans 1,3-butadiene. II. Ab initio multiple spawning simulations

    Science.gov (United States)

    Glover, William J.; Mori, Toshifumi; Schuurman, Michael S.; Boguslavskiy, Andrey E.; Schalk, Oliver; Stolow, Albert; Martínez, Todd J.

    2018-04-01

    The excited state non-adiabatic dynamics of the smallest polyene, trans 1,3-butadiene (BD), has long been the subject of controversy due to its strong coupling, ultrafast time scales and the difficulties that theory faces in describing the relevant electronic states in a balanced fashion. Here we apply Ab Initio Multiple Spawning (AIMS) using state-averaged complete active space multistate second order perturbation theory [SA-3-CAS(4/4)-MSPT2] which describes both static and dynamic electron correlation effects, providing a balanced description of both the initially prepared bright 11Bu (ππ*) state and non-adiabatically coupled dark 21Ag state of BD. Importantly, AIMS allows for on-the-fly calculations of experimental observables. We validate our approach by directly simulating the time resolved photoelectron-photoion coincidence spectroscopy results presented in Paper I [A. E. Boguslavskiy et al., J. Chem. Phys. 148, 164302 (2018)], demonstrating excellent agreement with experiment. Our simulations reveal that the initial excitation to the 11Bu state rapidly evolves via wavepacket dynamics that follow both bright- and dark-state pathways as well as mixtures of these. In order to test the sensitivity of the AIMS results to the relative ordering of states, we considered two hypothetical scenarios biased toward either the bright 1Bu or the dark 21Ag state. In contrast with AIMS/SA-3-CAS(4/4)-MSPT2 simulations, neither of these scenarios yields favorable agreement with experiment. Thus, we conclude that the excited state non-adiabatic dynamics in BD involves both of these ultrafast pathways.

  8. Scattering of a proton with the Li{sub 4} cluster: Non-adiabatic molecular dynamics description based on time-dependent density-functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Castro, A., E-mail: acastro@bifi.es [Institute for Biocomputation and Physics of Complex Systems (BIFI) and Zaragoza Scientific Center for Advanced Modelling (ZCAM), University of Zaragoza, 50018 Zaragoza (Spain); Isla, M. [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, 47005 Valladolid (Spain); Martinez, Jose I. [Departamento de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid, ES-28049 Madrid (Spain); Alonso, J.A. [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, 47005 Valladolid (Spain)

    2012-05-03

    Graphical abstract: Two trajectories for the collision of a proton with the Lithium tetramer. On the left, the proton is scattered away, and a Li{sub 2} molecule plus two isolated Lithium atoms result. On the right, the proton is captured and a LiH molecule is created. Highlights: Black-Right-Pointing-Pointer Scattering of a proton with Lithium clusters described from first principles. Black-Right-Pointing-Pointer Description based on non-adiabatic molecular dynamics. Black-Right-Pointing-Pointer The electronic structure is described with time-dependent density-functional theory. Black-Right-Pointing-Pointer The method allows to discern reaction channels depending on initial parameters. - Abstract: We have employed non-adiabatic molecular dynamics based on time-dependent density-functional theory to characterize the scattering behavior of a proton with the Li{sub 4} cluster. This technique assumes a classical approximation for the nuclei, effectively coupled to the quantum electronic system. This time-dependent theoretical framework accounts, by construction, for possible charge transfer and ionization processes, as well as electronic excitations, which may play a role in the non-adiabatic regime. We have varied the incidence angles in order to analyze the possible reaction patterns. The initial proton kinetic energy of 10 eV is sufficiently high to induce non-adiabatic effects. For all the incidence angles considered the proton is scattered away, except in one interesting case in which one of the Lithium atoms captures it, forming a LiH molecule. This theoretical formalism proves to be a powerful, effective and predictive tool for the analysis of non-adiabatic processes at the nanoscale.

  9. Ultrafast dual photoresponse of isolated biological chromophores: link to the photoinduced mode-specific non-adiabatic dynamics in proteins

    DEFF Research Database (Denmark)

    Bochenkova, Anastasia; Andersen, Lars Henrik

    2013-01-01

    The anionic wild-type Green Fluorescent Protein (GFP) chromophore defines the entire class of naturally occurring chromophores, which are based on the oxydized tyrosine side chain. The GFP chromophore exhibits an enriched photoinduced non-adiabatic dynamics in the multiple excited-state decay cha...

  10. Dynamics of dissociation versus ionization in strong laser fields

    International Nuclear Information System (INIS)

    DiMauro, L.F.; Yang, B.

    1993-01-01

    In this paper, experimental results are presented which clearly demonstrate the effectiveness that an external field has in altering the dissociation dynamics. The experiment examines the strong-field dissociation dynamics of molecular hydrogen ions and its deuterated isotopes. These studies involve multiphoton excitation in the intensity regime of 10 11-14 W/cm 2 with the fundamental and second harmonic of a ND:YAG or ND:YLF laser system. Measurements include energy resolved electron and mass spectroscopy which provide useful probes in elucidating the interaction dynamics predicted by existing models. The example this in this paper, examines the strong-field dissociation of H 2 + , HD + , and D 2 + at green (0.5 μm) and (1μm) frequencies. The diatomic ions are formed via multiphonon ionization of the neutral precursor which is physically separable from the dissociation process. This study provides the first observation of the dynamics associated with the above threshold dissociation (ATD) process and analogies will be made with the more familiar above threshold ionization (ATI) phenomenon

  11. Mode-selective chemistry on metal surfaces: The dissociative chemisorption of CH{sub 4} on Pt(111)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Han; Jackson, Bret, E-mail: jackson@chem.umass.edu [Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003 (United States)

    2016-05-14

    A quantum approach based on an expansion in vibrationally adiabatic eigenstates is used to explore CH{sub 4} dissociation on Pt(111). Computed sticking probabilities for molecules in the ground, 1v{sub 3} and 2v{sub 3}, states are in very good agreement with the available experimental data, reproducing the variation in reactivity with collision energy and vibrational state. As was found in similar studies on Ni(100) and Ni(111), exciting the 1v{sub 1} symmetric stretch of CH{sub 4} is more effective at promoting the dissociative chemisorption of CH{sub 4} than exciting the 1v{sub 3} antisymmetric stretch. This behavior is explained in terms of symmetry, mode-softening, and nonadiabatic transitions between vibrationally adiabatic states. We find that the efficacies of the bending modes for promoting reaction are reasonably large, and similar to the 1v{sub 3} state. The vibrational efficacies for promoting reaction on Ni(111) are larger than for reaction on Pt(111), due to the larger nonadiabatic couplings. Our computed sticking probabilities are in good agreement with results from recent ab initio molecular dynamics and reactive force field studies.

  12. Excited state non-adiabatic dynamics of the smallest polyene, trans 1,3-butadiene. II. Ab initio multiple spawning simulations.

    Science.gov (United States)

    Glover, William J; Mori, Toshifumi; Schuurman, Michael S; Boguslavskiy, Andrey E; Schalk, Oliver; Stolow, Albert; Martínez, Todd J

    2018-04-28

    The excited state non-adiabatic dynamics of the smallest polyene, trans 1,3-butadiene (BD), has long been the subject of controversy due to its strong coupling, ultrafast time scales and the difficulties that theory faces in describing the relevant electronic states in a balanced fashion. Here we apply Ab Initio Multiple Spawning (AIMS) using state-averaged complete active space multistate second order perturbation theory [SA-3-CAS(4/4)-MSPT2] which describes both static and dynamic electron correlation effects, providing a balanced description of both the initially prepared bright 1 1 B u (ππ*) state and non-adiabatically coupled dark 2 1 A g state of BD. Importantly, AIMS allows for on-the-fly calculations of experimental observables. We validate our approach by directly simulating the time resolved photoelectron-photoion coincidence spectroscopy results presented in Paper I [A. E. Boguslavskiy et al., J. Chem. Phys. 148, 164302 (2018)], demonstrating excellent agreement with experiment. Our simulations reveal that the initial excitation to the 1 1 B u state rapidly evolves via wavepacket dynamics that follow both bright- and dark-state pathways as well as mixtures of these. In order to test the sensitivity of the AIMS results to the relative ordering of states, we considered two hypothetical scenarios biased toward either the bright 1 B u or the dark 2 1 A g state. In contrast with AIMS/SA-3-CAS(4/4)-MSPT2 simulations, neither of these scenarios yields favorable agreement with experiment. Thus, we conclude that the excited state non-adiabatic dynamics in BD involves both of these ultrafast pathways.

  13. Non-adiabatic Excited State Molecule Dynamics Modeling of Photochemistry and Photophysics of Materials

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Tammie Renee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tretiak, Sergei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-06

    Understanding and controlling excited state dynamics lies at the heart of all our efforts to design photoactive materials with desired functionality. This tailor-design approach has become the standard for many technological applications (e.g., solar energy harvesting) including the design of organic conjugated electronic materials with applications in photovoltaic and light-emitting devices. Over the years, our team has developed efficient LANL-based codes to model the relevant photophysical processes following photoexcitation (spatial energy transfer, excitation localization/delocalization, and/or charge separation). The developed approach allows the non-radiative relaxation to be followed on up to ~10 ps timescales for large realistic molecules (hundreds of atoms in size) in the realistic solvent dielectric environment. The Collective Electronic Oscillator (CEO) code is used to compute electronic excited states, and the Non-adiabatic Excited State Molecular Dynamics (NA-ESMD) code is used to follow the non-adiabatic dynamics on multiple coupled Born-Oppenheimer potential energy surfaces. Our preliminary NA-ESMD simulations have revealed key photoinduced mechanisms controlling competing interactions and relaxation pathways in complex materials, including organic conjugated polymer materials, and have provided a detailed understanding of photochemical products and intermediates and the internal conversion process during the initiation of energetic materials. This project will be using LANL-based CEO and NA-ESMD codes to model nonradiative relaxation in organic and energetic materials. The NA-ESMD and CEO codes belong to a class of electronic structure/quantum chemistry codes that require large memory, “long-queue-few-core” distribution of resources in order to make useful progress. The NA-ESMD simulations are trivially parallelizable requiring ~300 processors for up to one week runtime to reach a meaningful restart point.

  14. Nonadiabatic quantum dynamics and laser control of Br2 in solid argon.

    Science.gov (United States)

    Accardi, A; Borowski, A; Kühn, O

    2009-07-02

    A five-dimensional reaction surface-vibronic coupling model is introduced to describe the B- to C-state predissociation dynamics of Br(2) occupying a double substitutional lattice site in a face-centered cubic argon crystal at low temperatures. The quantum dynamics driven by a Franck-Condon vertical excitation is investigated, revealing the role of matrix cage compression for efficient nonadiabatic transitions. Vibrational preexcitation of the Br(2) bond in the electronic ground state can be used to access a different regime of predissociation which does not require substantial matrix compression because the Franck-Condon window shifts into the energetic range of the B-C level crossing. Using optimal control theory, it is shown how vibrational preexcitation can be achieved via a pump-dump-type mechanism involving the repulsive C state.

  15. Tensor-Train Split-Operator Fourier Transform (TT-SOFT) Method: Multidimensional Nonadiabatic Quantum Dynamics.

    Science.gov (United States)

    Greene, Samuel M; Batista, Victor S

    2017-09-12

    We introduce the "tensor-train split-operator Fourier transform" (TT-SOFT) method for simulations of multidimensional nonadiabatic quantum dynamics. TT-SOFT is essentially the grid-based SOFT method implemented in dynamically adaptive tensor-train representations. In the same spirit of all matrix product states, the tensor-train format enables the representation, propagation, and computation of observables of multidimensional wave functions in terms of the grid-based wavepacket tensor components, bypassing the need of actually computing the wave function in its full-rank tensor product grid space. We demonstrate the accuracy and efficiency of the TT-SOFT method as applied to propagation of 24-dimensional wave packets, describing the S 1 /S 2 interconversion dynamics of pyrazine after UV photoexcitation to the S 2 state. Our results show that the TT-SOFT method is a powerful computational approach for simulations of quantum dynamics of polyatomic systems since it avoids the exponential scaling problem of full-rank grid-based representations.

  16. Nonadiabatic effect on the quantum heat flux control.

    Science.gov (United States)

    Uchiyama, Chikako

    2014-05-01

    We provide a general formula of quantum transfer that includes the nonadiabatic effect under periodic environmental modulation by using full counting statistics in Hilbert-Schmidt space. Applying the formula to an anharmonic junction model that interacts with two bosonic environments within the Markovian approximation, we find that the quantum transfer is divided into the adiabatic (dynamical and geometrical phases) and nonadiabatic contributions. This extension shows the dependence of quantum transfer on the initial condition of the anharmonic junction just before the modulation, as well as the characteristic environmental parameters such as interaction strength and cut-off frequency of spectral density. We show that the nonadiabatic contribution represents the reminiscent effect of past modulation including the transition from the initial condition of the anharmonic junction to a steady state determined by the very beginning of the modulation. This enables us to tune the frequency range of modulation, whereby we can obtain the quantum flux corresponding to the geometrical phase by setting the initial condition of the anharmonic junction.

  17. Classical molecular dynamics simulation of electronically non-adiabatic processes.

    Science.gov (United States)

    Miller, William H; Cotton, Stephen J

    2016-12-22

    Both classical and quantum mechanics (as well as hybrids thereof, i.e., semiclassical approaches) find widespread use in simulating dynamical processes in molecular systems. For large chemical systems, however, which involve potential energy surfaces (PES) of general/arbitrary form, it is usually the case that only classical molecular dynamics (MD) approaches are feasible, and their use is thus ubiquitous nowadays, at least for chemical processes involving dynamics on a single PES (i.e., within a single Born-Oppenheimer electronic state). This paper reviews recent developments in an approach which extends standard classical MD methods to the treatment of electronically non-adiabatic processes, i.e., those that involve transitions between different electronic states. The approach treats nuclear and electronic degrees of freedom (DOF) equivalently (i.e., by classical mechanics, thereby retaining the simplicity of standard MD), and provides "quantization" of the electronic states through a symmetrical quasi-classical (SQC) windowing model. The approach is seen to be capable of treating extreme regimes of strong and weak coupling between the electronic states, as well as accurately describing coherence effects in the electronic DOF (including the de-coherence of such effects caused by coupling to the nuclear DOF). A survey of recent applications is presented to illustrate the performance of the approach. Also described is a newly developed variation on the original SQC model (found universally superior to the original) and a general extension of the SQC model to obtain the full electronic density matrix (at no additional cost/complexity).

  18. Nonadiabatic dynamics of electron injection into organic molecules

    International Nuclear Information System (INIS)

    Zhu Li-Ping; Qiu Yu; Tong Guo-Ping

    2012-01-01

    We numerically investigate the injection process of electrons from metal electrodes to one-dimensional organic molecules by combining the extended Su—Schrieffer—Heeger (SSH) model with a nonadiabatic dynamics method. It is found that a match between the Fermi level of electrodes and the highest occupied molecular orbital (HOMO) or the lowest unoccupied molecular orbital (LUMO) of organic molecules can be greatly affected by the length of the organic chains, which has a great impact on electron injection. The correlation between oligomers and electrodes is found to open more efficient channels for electron injection as compared with that in polymer/electrode structures. For oligomer/electrode structures, we show that the Schottky barrier essentially does not affect the electron injection as the electrode work function is smaller than a critical value. This means that the Schottky barrier is pinned for a small work-function electrode. For polymer/electrode structures, we find that it is possible for the Fermi level of electrodes to be pinned to the polaronic level. The condition under which the Fermi level of electrodes exceeds the polaronic level of polymers is shown to not always lead to spontaneous electron transfer from electrodes to polymers. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  19. Nonadiabatic production of spinor condensates with a quadrupole-Ioffe-configuration trap

    International Nuclear Information System (INIS)

    Zhang, P.; Xu, Z.; You, L.

    2006-01-01

    Motivated by the recent experimental observation of multicomponent spinor condensates via a time-dependent quadrupole-Ioffe-configuration trap, we provide a general framework for the investigation of nonadiabatic Landau-Zener dynamics of a hyperfine spin, e.g., from an atomic magnetic dipole moment coupled to a weak time-dependent magnetic (B-) field. The spin flipped population distribution, or the so-called Majorona formula, is expressed in terms of system parameters and experimental observables; thus, the distribution provides much needed insight into the underlying mechanism for the production of spinor condensates due to nonadiabatic level crossings

  20. Vibrational nonadiabaticity and tunneling effects in transition state theory

    International Nuclear Information System (INIS)

    Marcus, R.A.

    1979-01-01

    The usual quantum mechanical derivation of transition state theory is a statistical one (a quasi-equilibrium is assumed) or dynamical. The typical dynamical one defines a set of internal states and assumes vibrational adiabaticity. Effects of nonadiabaticity before and after the transition state are included in the present derivation, assuming a classical treatment of the reaction coordinate. The relation to a dynamical derivation of classical mechanical transition state theory is described, and tunneling effects are considered

  1. Non-adiabatic perturbations in multi-component perfect fluids

    Energy Technology Data Exchange (ETDEWEB)

    Koshelev, N.A., E-mail: koshna71@inbox.ru [Ulyanovsk State University, Leo Tolstoy str 42, 432970 (Russian Federation)

    2011-04-01

    The evolution of non-adiabatic perturbations in models with multiple coupled perfect fluids with non-adiabatic sound speed is considered. Instead of splitting the entropy perturbation into relative and intrinsic parts, we introduce a set of symmetric quantities, which also govern the non-adiabatic pressure perturbation in models with energy transfer. We write the gauge invariant equations for the variables that determine on a large scale the non-adiabatic pressure perturbation and the rate of changes of the comoving curvature perturbation. The analysis of evolution of the non-adiabatic pressure perturbation has been made for several particular models.

  2. Non-adiabatic perturbations in multi-component perfect fluids

    International Nuclear Information System (INIS)

    Koshelev, N.A.

    2011-01-01

    The evolution of non-adiabatic perturbations in models with multiple coupled perfect fluids with non-adiabatic sound speed is considered. Instead of splitting the entropy perturbation into relative and intrinsic parts, we introduce a set of symmetric quantities, which also govern the non-adiabatic pressure perturbation in models with energy transfer. We write the gauge invariant equations for the variables that determine on a large scale the non-adiabatic pressure perturbation and the rate of changes of the comoving curvature perturbation. The analysis of evolution of the non-adiabatic pressure perturbation has been made for several particular models

  3. Pseudorotational dynamics of small molecular species

    International Nuclear Information System (INIS)

    Hagelberg, F.

    2002-01-01

    The electron nuclear dynamics (END) theory was designed to provide a full description of the dynamic development of the electronic system. It is independent of any potential energy surface constructions. The dynamic behavior of molecules close to the threshold of dissociation was the objective of this study. Thus, simulations based on END theory were performed with the aim to extend the current understanding of the dynamic features of pseudorotational into a non-adiabatic regime. Electron dynamics of triatomic species (H 3 + and Li 3 + ) in terms of electronic angular momentum expectation values were characterized. Finally, it is shown that the expansion coefficients which carry the information about the excitation content of the electronic system at any stage of the motional process can be calculated. (nevyjel)

  4. Photoinduced Ultrafast Intramolecular Excited-State Energy Transfer in the Silylene-Bridged Biphenyl and Stilbene (SBS) System: A Nonadiabatic Dynamics Point of View.

    Science.gov (United States)

    Wang, Jun; Huang, Jing; Du, Likai; Lan, Zhenggang

    2015-07-09

    The photoinduced intramolecular excited-state energy-transfer (EET) process in conjugated polymers has received a great deal of research interest because of its important role in the light harvesting and energy transport of organic photovoltaic materials in photoelectric devices. In this work, the silylene-bridged biphenyl and stilbene (SBS) system was chosen as a simplified model system to obtain physical insight into the photoinduced intramolecular energy transfer between the different building units of the SBS copolymer. In the SBS system, the vinylbiphenyl and vinylstilbene moieties serve as the donor (D) unit and the acceptor (A) unit, respectively. The ultrafast excited-state dynamics of the SBS system was investigated from the point of view of nonadiabatic dynamics with the surface-hopping method at the TDDFT level. The first two excited states (S1 and S2) are characterized by local excitations at the acceptor (vinylstilbene) and donor (vinylbiphenyl) units, respectively. Ultrafast S2-S1 decay is responsible for the intramolecular D-A excitonic energy transfer. The geometric distortion of the D moiety play an essential role in this EET process, whereas the A moiety remains unchanged during the nonadiabatic dynamics simulation. The present work provides a direct dynamical approach to understand the ultrafast intramolecular energy-transfer dynamics in SBS copolymers and other similar organic photovoltaic copolymers.

  5. The quantum dynamics of electronically nonadiabatic chemical reactions

    Science.gov (United States)

    Truhlar, Donald G.

    1993-01-01

    Considerable progress was achieved on the quantum mechanical treatment of electronically nonadiabatic collisions involving energy transfer and chemical reaction in the collision of an electronically excited atom with a molecule. In the first step, a new diabatic representation for the coupled potential energy surfaces was created. A two-state diabatic representation was developed which was designed to realistically reproduce the two lowest adiabatic states of the valence bond model and also to have the following three desirable features: (1) it is more economical to evaluate; (2) it is more portable; and (3) all spline fits are replaced by analytic functions. The new representation consists of a set of two coupled diabatic potential energy surfaces plus a coupling surface. It is suitable for dynamics calculations on both the electronic quenching and reaction processes in collisions of Na(3p2p) with H2. The new two-state representation was obtained by a three-step process from a modified eight-state diatomics-in-molecules (DIM) representation of Blais. The second step required the development of new dynamical methods. A formalism was developed for treating reactions with very general basis functions including electronically excited states. Our formalism is based on the generalized Newton, scattered wave, and outgoing wave variational principles that were used previously for reactive collisions on a single potential energy surface, and it incorporates three new features: (1) the basis functions include electronic degrees of freedom, as required to treat reactions involving electronic excitation and two or more coupled potential energy surfaces; (2) the primitive electronic basis is assumed to be diabatic, and it is not assumed that it diagonalizes the electronic Hamiltonian even asymptotically; and (3) contracted basis functions for vibrational-rotational-orbital degrees of freedom are included in a very general way, similar to previous prescriptions for locally

  6. Nonadiabatic transitions in electrostatically trapped ammonia molecules

    International Nuclear Information System (INIS)

    Kirste, Moritz; Schnell, Melanie; Meijer, Gerard; Sartakov, Boris G.

    2009-01-01

    Nonadiabatic transitions are known to be major loss channels for atoms in magnetic traps but have thus far not been experimentally reported upon for trapped molecules. We have observed and quantified losses due to nonadiabatic transitions for three isotopologues of ammonia in electrostatic traps by comparing the trapping times in traps with a zero and a nonzero electric field at the center. Nonadiabatic transitions are seen to dominate the overall loss rate even for the present samples that are at relatively high temperatures of 30 mK. It is anticipated that losses due to nonadiabatic transitions in electric fields are omnipresent in ongoing experiments on cold molecules.

  7. Communication: On the competition between adiabatic and nonadiabatic dynamics in vibrationally mediated ammonia photodissociation in its A band

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Changjian [Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210093 (China); Zhu, Xiaolei; Yarkony, David R., E-mail: jianyi.m@gmail.com, E-mail: yarkony@jhu.edu, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Ma, Jianyi, E-mail: jianyi.m@gmail.com, E-mail: yarkony@jhu.edu, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065 (China); Xie, Daiqian, E-mail: jianyi.m@gmail.com, E-mail: yarkony@jhu.edu, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210093 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Guo, Hua, E-mail: jianyi.m@gmail.com, E-mail: yarkony@jhu.edu, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2015-03-07

    Non-adiabatic processes play an important role in photochemistry, but the mechanism for conversion of electronic energy to chemical energy is still poorly understood. To explore the possibility of vibrational control of non-adiabatic dynamics in a prototypical photoreaction, namely, the A-band photodissociation of NH{sub 3}(X{sup ~1}A{sub 1}), full-dimensional state-to-state quantum dynamics of symmetric or antisymmetric stretch excited NH{sub 3}(X{sup ~1}A{sub 1}) is investigated on recently developed coupled diabatic potential energy surfaces. The experimentally observed H atom kinetic energy distributions are reproduced. However, contrary to previous inferences, the NH{sub 2}(A{sup ~2}A{sub 1})/NH{sub 2}(X{sup ~2}B{sub 1}) branching ratio is found to be small regardless of the initial preparation of NH{sub 3}(X{sup ~1}A{sub 1}), while the internal state distribution of the preeminent fragment, NH{sub 2}(X{sup ~2}B{sub 1}), is found to depend strongly on the initial vibrational excitation of NH{sub 3}(X{sup ~1}A{sub 1}). The slow H atoms in photodissociation mediated by the antisymmetric stretch fundamental state are due to energy sequestered in the internally excited NH{sub 2}(X{sup ~2}B{sub 1}) fragment, rather than in NH{sub 2}(A{sup ~2}A{sub 1}) as previously proposed. The high internal excitation of the NH{sub 2}(X{sup ~2}B{sub 1}) fragment is attributed to the torques exerted on the molecule as it passes through the conical intersection seam to the ground electronic state of NH{sub 3}. Thus in this system, contrary to previous assertions, the control of electronic state branching by selective excitation of ground state vibrational modes is concluded to be ineffective. The juxtaposition of precise quantum mechanical results with complementary results based on quasi-classical surface hopping trajectories provides significant insights into the non-adiabatic process.

  8. Comparison of dynamical aspects of nonadiabatic electron, proton, and proton-coupled electron transfer reactions

    International Nuclear Information System (INIS)

    Hatcher, Elizabeth; Soudackov, Alexander; Hammes-Schiffer, Sharon

    2005-01-01

    The dynamical aspects of a model proton-coupled electron transfer (PCET) reaction in solution are analyzed with molecular dynamics simulations. The rate for nonadiabatic PCET is expressed in terms of a time-dependent probability flux correlation function. The impact of the proton donor-acceptor and solvent dynamics on the probability flux is examined. The dynamical behavior of the probability flux correlation function is dominated by a solvent damping term that depends on the energy gap correlation function. The proton donor-acceptor motion does not impact the dynamical behavior of the probability flux correlation function but does influence the magnitude of the rate. The approximations previously invoked for the calculation of PCET rates are tested. The effects of solvent damping on the proton donor-acceptor vibrational motion are found to be negligible, and the short-time solvent approximation, in which only equilibrium fluctuations of the solvent are considered, is determined to be valid for these types of reactions. The analysis of PCET reactions is compared to previous analyses of single electron and proton transfer reactions. The dynamical behavior is qualitatively similar for all three types of reactions, but the time scale of the decay of the probability flux correlation function is significantly longer for single proton transfer than for PCET and single electron transfer due to a smaller solvent reorganization energy for proton transfer

  9. Ultrafast dissociation: An unexpected tool for probing molecular dynamics

    International Nuclear Information System (INIS)

    Morin, Paul; Miron, Catalin

    2012-01-01

    Highlights: ► Ultrafast dissociation has been investigated by means of XPS and mass spectrometry. ► The interplay between electron relaxation and molecular dynamics is evidenced. ► Extension toward polyatomics, clusters, adsorbed molecules is considered. ► Quantum effects (spectral hole, angular effects) evidence the molecular field anisotropy. -- Abstract: Ultrafast dissociation following core–shell excitation into an antibonding orbital led to the early observation in HBr of atomic Auger lines associated to the decay of dissociated excited atoms. The purpose of this article is to review the very large variety of systems where such a situation has been encountered, extending from simple diatomic molecules toward more complex systems like polyatomics, clusters, or adsorbed molecules. Interestingly, this phenomenon has revealed an extremely rich and powerful tool for probing nuclear dynamics and its subtle interplay with electron relaxation occurring on a comparable time scale. Consequently this review covers a surprisingly large period, starting in 1986 and still ongoing.

  10. Active vs. spectator modes in nonadiabatic photodissociation dynamics of the hydroxymethyl radical via the 22A(3s) Rydberg state

    Science.gov (United States)

    Xie, Changjian; Guo, Hua

    2018-01-01

    The choice of the active degrees of freedom (DOFs) is a pivotal issue in a reduced-dimensional model of quantum dynamics when a full-dimensional one is not feasible. Here, several five-dimensional (5D) models are used to investigate the nonadiabatic photodissociation dynamics of the hydroxymethyl (CH2OH) radical, which possesses nine internal DOFs, in its lowest absorption band. A normal-mode based scheme is used to identify the active and spectator modes, and its predictions are confirmed by 5D quantum dynamical calculations. Our results underscore the important role of the CO stretching mode in the photodissociation dynamics of CH2OH, originating from the photo-induced promotion of an electron from the half-occupied π*CO antibonding orbital to a carbon Rydberg orbital.

  11. Nonadiabatic semiclassical dynamics in the mixed quantum-classical initial value representation

    Science.gov (United States)

    Church, Matthew S.; Hele, Timothy J. H.; Ezra, Gregory S.; Ananth, Nandini

    2018-03-01

    We extend the Mixed Quantum-Classical Initial Value Representation (MQC-IVR), a semiclassical method for computing real-time correlation functions, to electronically nonadiabatic systems using the Meyer-Miller-Stock-Thoss (MMST) Hamiltonian in order to treat electronic and nuclear degrees of freedom (dofs) within a consistent dynamic framework. We introduce an efficient symplectic integration scheme, the MInt algorithm, for numerical time evolution of the phase space variables and monodromy matrix under the non-separable MMST Hamiltonian. We then calculate the probability of transmission through a curve crossing in model two-level systems and show that MQC-IVR reproduces quantum-limit semiclassical results in good agreement with exact quantum methods in one limit, and in the other limit yields results that are in keeping with classical limit semiclassical methods like linearized IVR. Finally, exploiting the ability of the MQC-IVR to quantize different dofs to different extents, we present a detailed study of the extents to which quantizing the nuclear and electronic dofs improves numerical convergence properties without significant loss of accuracy.

  12. Dynamics of elementary processes in the gas phase O2 and CO

    International Nuclear Information System (INIS)

    Bacchus-Montabonel, M.C.; Tergiman, Y.S.; Vaeck, N.; Baloitcha, E.; Desouter-Lecomte, M.

    2002-01-01

    Complex reaction mechanisms are involved in the radiation of biomolecules, their dynamics may proceed by a series of elementary processes, induced often by a fast reaction step, followed by relaxation or reorganization of the molecular system. The time-dependent wave packet method tested on the Si 4+ + He system, provides a clear and physical insight into the dynamics of theses process. Photodissociation experiments were performed, in particular the dissociation of bromoacetylchloride Br-CH 2 -COCl, to study the competitive dissociation of C-Cl and C-Br bonds. The dissociation leaded preferentially to C- Cl breaking, although the C-Br bond is thermodynamically weaker. This result is in disagreement with statistical theories, as the branching ratio depends not only on the relative height of the corresponding barriers, but also on non-adiabatic transitions arising from interactions between the different excited states. The effects depends on the distance between the C=O and C-X chromophores and on the conforming molecule. (nevyjel)

  13. Nonadiabatic dynamics in the semiclassical Liouville representation: Locality, transformation theory, and the energy budget

    Energy Technology Data Exchange (ETDEWEB)

    Martens, Craig C., E-mail: cmartens@uci.edu

    2016-12-20

    In this paper, we revisit the semiclassical Liouville approach to describing molecular dynamics with electronic transitions using classical trajectories. Key features of the formalism are highlighted. The locality in phase space and presence of nonclassical terms in the generalized Liouville equations are emphasized and discussed in light of trajectory surface hopping methodology. The representation dependence of the coupled semiclassical Liouville equations in the diabatic and adiabatic bases are discussed and new results for the transformation theory of the Wigner functions representing the corresponding density matrix elements given. We show that the diagonal energies of the state populations are not conserved during electronic transitions, as energy is stored in the electronic coherence. We discuss the implications of this observation for the validity of imposing strict energy conservation in trajectory based methods for simulating nonadiabatic processes.

  14. Nonadiabatic Spin Torque Investigated Using Thermally Activated Magnetic Domain Wall Dynamics

    DEFF Research Database (Denmark)

    Eltschka, M.; Woetzel, Mathias; Rhensius, J.

    2010-01-01

    of the DW as a quasiparticle in a one-dimensional potential landscape. By injecting small currents, the potential is modified, allowing for the determination of the nonadiabatic spin torque: βt=0.010±0.004 for a transverse DW and βv=0.073±0.026 for a vortex DW. The larger value is attributed to the higher...

  15. Different dynamic behaviors of the dissociation and recombination reactions in a model calculation of polyethylene by first-principles steered molecular dynamics simulation

    International Nuclear Information System (INIS)

    Higuchi, Yuji; Ishikawa, Takeshi; Ozawa, Nobuki; Chazeau, Laurent; Cavaillé, Jean-Yves; Kubo, Momoji

    2015-01-01

    Highlights: • We study the different dynamics of dissociation and recombination processes. • Hydrogen at the chain ends collides each other in the recombination process. • Dissociation and recombination processes take different pathway. - Abstract: We investigate the different dynamics of the stress-induced dissociation and recombination reactions in a model of polyethylene by a first-principles molecular dynamics simulation at the B3LYP/6-31g(d) level. The dissociation under external forces acting on the chemical reaction site at 300 K follows the same pathway as the one calculated by the static first-principles method because it has a similar activation barrier to that of the static first-principles calculation. On the other hand, in the recombination process, thermal fluctuations causes collisions between hydrogen atoms at the chain ends. Furthermore, when external forces do not directly act on the chemical reaction site, two different dissociation processes are observed. On the other hand, recombination process is not observed due to rarely contact of the radical carbon. These results indicate that dissociation and recombination dynamics are very different, showing the importance of the dynamic calculation.

  16. Atomistic absorption spectra and non-adiabatic dynamics of the LH2 complex with a GPU-accelerated ab initio exciton model

    Science.gov (United States)

    Glowacki, David

    Recently, we outlined an efficient multi-tiered parallel excitonic framework that utilizes time dependent density functional theory (TDDFT) to calculate ground/excited state energies and gradients of large supramolecular complexes in atomistic detail. In this paper, we apply our ab initioexciton framework to the 27 coupled bacteriocholorophyll-a chromophores which make up the LH2 complex, using it to compute linear absorption spectra and short-time, on-the-fly nonadiabatic surface-hopping (SH) dynamics of electronically excited LH2. Our ab initio exciton model includes two key parameters whose values are determined by fitting to experiment: d, which is added to the diagonal elements, corrects for the error in TDDFT vertical excitation energies on a single chromophore; and e, which occurs on the off-diagonal matrix elements, describes the average dielectric screening of the inter-chromophore transition-dipole coupling. Using snapshots obtained from equilibrium molecular dynamics simulations (MD) of LH2, best-fit values of both d and e were obtained by fitting to the thermally broadened experimental absorption spectrum within the Frank-Condon approximation, providing a linear absorption spectrum that agrees reasonably well with the experimental observations. We follow the nonadiabatic dynamics using surface hopping to construct time-resolved visualizations of the EET dynamics in the sub-picosecond regime following photoexcitation. This provides some qualitative insight into the excitonic energy transfer (EET) that results from atomically resolved vibrational fluctuations of the chromophores. The dynamical picture that emerges is one of rapidly fluctuating eigenstates that are delocalized over multiple chromophores and undergo frequent crossing on a femtosecond timescale as a result of the underlying chromophore vibrational dynamics. The eigenstate fluctuations arise from disorder in both the diagonal chromophore site energies and the off-diagonal inter

  17. Electronic energy transfer through non-adiabatic vibrational-electronic resonance. I. Theory for a dimer

    Science.gov (United States)

    Tiwari, Vivek; Peters, William K.; Jonas, David M.

    2017-10-01

    Non-adiabatic vibrational-electronic resonance in the excited electronic states of natural photosynthetic antennas drastically alters the adiabatic framework, in which electronic energy transfer has been conventionally studied, and suggests the possibility of exploiting non-adiabatic dynamics for directed energy transfer. Here, a generalized dimer model incorporates asymmetries between pigments, coupling to the environment, and the doubly excited state relevant for nonlinear spectroscopy. For this generalized dimer model, the vibrational tuning vector that drives energy transfer is derived and connected to decoherence between singly excited states. A correlation vector is connected to decoherence between the ground state and the doubly excited state. Optical decoherence between the ground and singly excited states involves linear combinations of the correlation and tuning vectors. Excitonic coupling modifies the tuning vector. The correlation and tuning vectors are not always orthogonal, and both can be asymmetric under pigment exchange, which affects energy transfer. For equal pigment vibrational frequencies, the nonadiabatic tuning vector becomes an anti-correlated delocalized linear combination of intramolecular vibrations of the two pigments, and the nonadiabatic energy transfer dynamics become separable. With exchange symmetry, the correlation and tuning vectors become delocalized intramolecular vibrations that are symmetric and antisymmetric under pigment exchange. Diabatic criteria for vibrational-excitonic resonance demonstrate that anti-correlated vibrations increase the range and speed of vibronically resonant energy transfer (the Golden Rule rate is a factor of 2 faster). A partial trace analysis shows that vibronic decoherence for a vibrational-excitonic resonance between two excitons is slower than their purely excitonic decoherence.

  18. Two-level system in spin baths: Non-adiabatic dynamics and heat transport

    Science.gov (United States)

    Segal, Dvira

    2014-04-01

    We study the non-adiabatic dynamics of a two-state subsystem in a bath of independent spins using the non-interacting blip approximation, and derive an exact analytic expression for the relevant memory kernel. We show that in the thermodynamic limit, when the subsystem-bath coupling is diluted (uniformly) over many (infinite) degrees of freedom, our expression reduces to known results, corresponding to the harmonic bath with an effective, temperature-dependent, spectral density function. We then proceed and study the heat current characteristics in the out-of-equilibrium spin-spin-bath model, with a two-state subsystem bridging two thermal spin-baths of different temperatures. We compare the behavior of this model to the case of a spin connecting boson baths, and demonstrate pronounced qualitative differences between the two models. Specifically, we focus on the development of the thermal diode effect, and show that the spin-spin-bath model cannot support it at weak (subsystem-bath) coupling, while in the intermediate-strong coupling regime its rectifying performance outplays the spin-boson model.

  19. Two-level system in spin baths: Non-adiabatic dynamics and heat transport

    Energy Technology Data Exchange (ETDEWEB)

    Segal, Dvira [Chemical Physics Theory Group, Department of Chemistry, University of Toronto, 80 Saint George St., Toronto, Ontario M5S 3H6 (Canada)

    2014-04-28

    We study the non-adiabatic dynamics of a two-state subsystem in a bath of independent spins using the non-interacting blip approximation, and derive an exact analytic expression for the relevant memory kernel. We show that in the thermodynamic limit, when the subsystem-bath coupling is diluted (uniformly) over many (infinite) degrees of freedom, our expression reduces to known results, corresponding to the harmonic bath with an effective, temperature-dependent, spectral density function. We then proceed and study the heat current characteristics in the out-of-equilibrium spin-spin-bath model, with a two-state subsystem bridging two thermal spin-baths of different temperatures. We compare the behavior of this model to the case of a spin connecting boson baths, and demonstrate pronounced qualitative differences between the two models. Specifically, we focus on the development of the thermal diode effect, and show that the spin-spin-bath model cannot support it at weak (subsystem-bath) coupling, while in the intermediate-strong coupling regime its rectifying performance outplays the spin-boson model.

  20. State-to-state photodissociation dynamics of triatomic molecules: H2O in the B band

    International Nuclear Information System (INIS)

    Jiang Bin; Xie Daiqian; Guo Hua

    2012-01-01

    State-to-state photodissociation dynamics of H 2 O in its B band has been investigated quantum mechanically on a new set of non-adiabatically coupled potential energy surfaces for the lowest two 1 A' states of H 2 O, which are developed at the internally contracted multi-reference configuration interaction level with the aug-cc-pVQZ basis set. Quantum dynamical calculations carried out using the Chebyshev propagator yield absorption spectra, product state distributions, branching ratios, and differential cross sections, which are in reasonably good agreement with the latest experimental results. Particular focus is placed here on the dependence of various dynamical observables on the photon energy. Detailed analyses of the dynamics have assigned the diffuse structure in absorption spectrum to short-time recurring dynamics near the HOH conical intersection. The non-adiabatic dissociation to the ground state OH product via the HOH conical intersection is facile, direct, fast, and produces rotationally hot OH(X-tilde) products. On the other hand, the adiabatic channel on the excited state leading to the OH(A-tilde) product is dominated by long-lived resonances, which depend sensitively on the potential energy surfaces.

  1. Non-adiabatic ab initio molecular dynamics of supersonic beam epitaxy of silicon carbide at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Taioli, Simone [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Department of Physics, University of Trento, Trento (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Perugia (Italy); Department of Chemistry, University of Bologna, Bologna (Italy); Garberoglio, Giovanni [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Simonucci, Stefano [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Perugia (Italy); Department of Physics, University of Camerino, Camerino (Italy); Beccara, Silvio a [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Department of Physics, University of Trento, Trento (Italy); Aversa, Lucrezia [Institute of Materials for Electronics and Magnetism, IMEM-CNR, Trento (Italy); Nardi, Marco [Institute of Materials for Electronics and Magnetism, IMEM-CNR, Trento (Italy); Institut fuer Physik, Humboldt-Universitaet zu Berlin, Berlin (Germany); Verucchi, Roberto [Institute of Materials for Electronics and Magnetism, FBK-CNR, Trento (Italy); Iannotta, Salvatore [Institute of Materials for Electronics and Magnetism, IMEM-CNR, Parma (Italy); Dapor, Maurizio [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Department of Materials Engineering and Industrial Technologies, University of Trento, Trento (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Padova (Italy); and others

    2013-01-28

    In this work, we investigate the processes leading to the room-temperature growth of silicon carbide thin films by supersonic molecular beam epitaxy technique. We present experimental data showing that the collision of fullerene on a silicon surface induces strong chemical-physical perturbations and, for sufficient velocity, disruption of molecular bonds, and cage breaking with formation of nanostructures with different stoichiometric character. We show that in these out-of-equilibrium conditions, it is necessary to go beyond the standard implementations of density functional theory, as ab initio methods based on the Born-Oppenheimer approximation fail to capture the excited-state dynamics. In particular, we analyse the Si-C{sub 60} collision within the non-adiabatic nuclear dynamics framework, where stochastic hops occur between adiabatic surfaces calculated with time-dependent density functional theory. This theoretical description of the C{sub 60} impact on the Si surface is in good agreement with our experimental findings.

  2. Non-adiabatic perturbations in Ricci dark energy model

    International Nuclear Information System (INIS)

    Karwan, Khamphee; Thitapura, Thiti

    2012-01-01

    We show that the non-adiabatic perturbations between Ricci dark energy and matter can grow both on superhorizon and subhorizon scales, and these non-adiabatic perturbations on subhorizon scales can lead to instability in this dark energy model. The rapidly growing non-adiabatic modes on subhorizon scales always occur when the equation of state parameter of dark energy starts to drop towards -1 near the end of matter era, except that the parameter α of Ricci dark energy equals to 1/2. In the case where α = 1/2, the rapidly growing non-adiabatic modes disappear when the perturbations in dark energy and matter are adiabatic initially. However, an adiabaticity between dark energy and matter perturbations at early time implies a non-adiabaticity between matter and radiation, this can influence the ordinary Sachs-Wolfe (OSW) effect. Since the amount of Ricci dark energy is not small during matter domination, the integrated Sachs-Wolfe (ISW) effect is greatly modified by density perturbations of dark energy, leading to a wrong shape of CMB power spectrum. The instability in Ricci dark energy is difficult to be alleviated if the effects of coupling between baryon and photon on dark energy perturbations are included

  3. Dynamical mechanism of charge separation by photoexcited generation of proton–electron pairs in organic molecular systems. A nonadiabatic electron wavepacket dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Kentaro, E-mail: kyamamoto@fukui.kyoto-u.ac.jp; Takatsuka, Kazuo, E-mail: kaztak@fukui.kyoto-u.ac.jp

    2016-08-22

    Graphical abstract: Asymptotic biradical state produced by the excited-state coupled proton–electron transfer (CPET), resulting in charge separation (proton–electron pair creation) on a proton–electron acceptor A, in a series of photochemical systems generally denoted as X–Mn–OH{sub 2}⋯A, where X = (OH, Ca(OH){sub 3}) and A = (N-methylformamidine, guanidine, imidazole, or ammonia clusters). - Abstract: In this perspective article, we review, along with presenting new results, a series of our theoretical analyses on the excited-state mechanism of charge separation (proton–electron pair creation) relevant to the photoinduced water-splitting reaction (2H{sub 2}O → 4H{sup +} + 4e{sup −} + O{sub 2}) in organic and biological systems, which quite often includes Mn clusters in various molecular configurations. The present mechanism is conceived to be universal in the triggering process of the photoexcited water splitting dynamics. In other words, any Mn-based catalytic charge separation is quite likely to be initiated according to this mechanism. As computationally tractable yet realistic models, we examine a series of systems generally expressed as X–Mn–OH{sub 2}⋯A, where X = (OH, Ca(OH){sub 3}) and A = (N-methylformamidine, guanidine, imidazole or ammonia cluster) in terms of the theory of nonadiabatic electron wavepacket dynamics. We first find both an electron and a proton are simultaneously transferred to the acceptors through conical intersections upon photoexcitation. In this mechanism, the electron takes different pathways from that of the proton and reaches the densely lying Rydberg-like states of the acceptors in the end, thereby inducing charge separation. Therefore the presence of the Rydberg-like diffused unoccupied states as an electron acceptor is critical for this reaction to proceed. We also have found another crucial nonadiabatic process that deteriorates the efficiency of charge separation by rendering the created pair of proton

  4. Wave Packet Simulation of Nonadiabatic Dynamics in Highly Excited 1,3-Dibromopropane

    DEFF Research Database (Denmark)

    Brogaard, Rasmus Y.; Møller, Klaus Braagaard; Sølling, Theis Ivan

    2008-01-01

    ]. In the experiment. DBP is excited to a Rydberg state 8 eV above the ground state. The interpretation of the results is that a torsional motion of the bromomethylene groups with a vibrational period of 680 is is activated upon excitation. The Rydberg state decays to a valence state, causing a dissociation of one...... of the carbon bromine bonds oil a time scale of 2.5 ps. Building the theoretical framework for the wave packet propagation around this model of the reaction dynamics, the Simulations reproduce, to a good extent, the time scales observed in the experiment. Furthermore. the Simulations provide insight into how...... the torsion motion influences the bond breakage, and C we can conclude that the mechanism that delays the dissociation is solely the electronic transition from the Rydberg state to the valence state and does not involve, for example, intramolecular vibrational energy redistribution (IVR)....

  5. Dissociation dynamics of methylal

    Energy Technology Data Exchange (ETDEWEB)

    Beaud, P; Frey, H -M; Gerber, T; Mischler, B; Radi, P P; Tzannis, A -P [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The dissociation of methylal is investigated using mass spectrometry, combined with a pyrolytic radical source and femtosecond pump probe experiments. Based on preliminary results two reaction paths of methylal dissociation are proposed and discussed. (author) 4 fig., 3 refs.

  6. Nonadiabatic effects in C-Br bond scission in the photodissociation of bromoacetyl chloride

    International Nuclear Information System (INIS)

    Valero, Rosendo; Truhlar, Donald G.

    2006-01-01

    Bromoacetyl chloride photodissociation has been interpreted as a paradigmatic example of a process in which nonadiabatic effects play a major role. In molecular beam experiments by Butler and co-workers [J. Chem. Phys. 95, 3848 (1991); J. Chem. Phys. 97, 355 (1992)], BrCH 2 C(O)Cl was prepared in its ground electronic state (S 0 ) and excited with a laser at 248 nm to its first excited singlet state (S 1 ). The two main ensuing photoreactions are the ruptures of the C-Cl bond and of the C-Br bond. A nonadiabatic model was proposed in which the C-Br scission is strongly suppressed due to nonadiabatic recrossing at the barrier formed by the avoided crossing between the S 1 and S 2 states. Recent reduced-dimensional dynamical studies lend support to this model. However, another interpretation that has been given for the experimental results is that the reduced probability of C-Br scission is a consequence of incomplete intramolecular energy redistribution. To provide further insight into this problem, we have studied the energetically lowest six singlet electronic states of bromoacetyl chloride by using an ab initio multiconfigurational perturbative electronic structure method. Stationary points (minima and saddle points) and minimum energy paths have been characterized on the S 0 and S 1 potential energy surfaces. The fourfold way diabatization method has been applied to transform five adiabatic excited electronic states to a diabatic representation. The diabatic potential energy matrix of the first five excited singlet states has been constructed along several cuts of the potential energy hypersurfaces. The thermochemistry of the photodissociation reactions and a comparison with experimental translational energy distributions strongly suggest that nonadiabatic effects dominate the C-Br scission, but that the reaction proceeds along the energetically allowed diabatic pathway to excited-state products instead of being nonadiabatically suppressed. This conclusion is

  7. Nonadiabatic transition path sampling

    International Nuclear Information System (INIS)

    Sherman, M. C.; Corcelli, S. A.

    2016-01-01

    Fewest-switches surface hopping (FSSH) is combined with transition path sampling (TPS) to produce a new method called nonadiabatic path sampling (NAPS). The NAPS method is validated on a model electron transfer system coupled to a Langevin bath. Numerically exact rate constants are computed using the reactive flux (RF) method over a broad range of solvent frictions that span from the energy diffusion (low friction) regime to the spatial diffusion (high friction) regime. The NAPS method is shown to quantitatively reproduce the RF benchmark rate constants over the full range of solvent friction. Integrating FSSH within the TPS framework expands the applicability of both approaches and creates a new method that will be helpful in determining detailed mechanisms for nonadiabatic reactions in the condensed-phase.

  8. Broken space-time symmetries and mechanisms of rectification of ac fields by nonlinear (non)adiabatic response

    DEFF Research Database (Denmark)

    Denisov, S.; Flach, S.; Ovchinnikov, A. A.

    2002-01-01

    We consider low-dimensional dynamical systems exposed to a heat bath and to additional ac fields. The presence of these ac fields may lead to a breaking of certain spatial or temporal symmetries, which in turn cause nonzero averages of relevant observables. Nonlinear (non)adiabatic response is em...... is employed to explain the effect. We consider a case of a particle in a periodic potential as an example and discuss the relevant symmetry breakings and the mechanisms of rectification of the current in such a system.......We consider low-dimensional dynamical systems exposed to a heat bath and to additional ac fields. The presence of these ac fields may lead to a breaking of certain spatial or temporal symmetries, which in turn cause nonzero averages of relevant observables. Nonlinear (non)adiabatic response...

  9. Nonadiabatic Dynamics for Electrons at Second-Order: Real-Time TDDFT and OSCF2.

    Science.gov (United States)

    Nguyen, Triet S; Parkhill, John

    2015-07-14

    We develop a new model to simulate nonradiative relaxation and dephasing by combining real-time Hartree-Fock and density functional theory (DFT) with our recent open-systems theory of electronic dynamics. The approach has some key advantages: it has been systematically derived and properly relaxes noninteracting electrons to a Fermi-Dirac distribution. This paper combines the new dissipation theory with an atomistic, all-electron quantum chemistry code and an atom-centered model of the thermal environment. The environment is represented nonempirically and is dependent on molecular structure in a nonlocal way. A production quality, O(N(3)) closed-shell implementation of our theory applicable to realistic molecular systems is presented, including timing information. This scaling implies that the added cost of our nonadiabatic relaxation model, time-dependent open self-consistent field at second order (OSCF2), is computationally inexpensive, relative to adiabatic propagation of real-time time-dependent Hartree-Fock (TDHF) or time-dependent density functional theory (TDDFT). Details of the implementation and numerical algorithm, including factorization and efficiency, are discussed. We demonstrate that OSCF2 approaches the stationary self-consistent field (SCF) ground state when the gap is large relative to k(b)T. The code is used to calculate linear-response spectra including the effects of bath dynamics. Finally, we show how our theory of finite-temperature relaxation can be used to correct ground-state DFT calculations.

  10. Multidimensional effects on dissociation of N-2 on Ru(0001)

    DEFF Research Database (Denmark)

    Diaz, C.; Vincent, J.K.; Krishnamohan, G.P.

    2006-01-01

    on density functional theory. The computed reaction probabilities are in good agreement with molecular beam experiments. Comparison to previous calculations shows that the rotation of N-2 and its motion along the surface affect the reactivity of N-2 much more than nonadiabatic effects.......The applicability of the Born-Oppenheimer approximation to molecule-metal surface reactions is presently a topic of intense debate. We have performed classical trajectory calculations on a prototype activated dissociation reaction, of N-2 on Ru(0001), using a potential energy surface based...

  11. Quantum Mechanics/Molecular Mechanics Free Energy Maps and Nonadiabatic Simulations for a Photochemical Reaction in DNA: Cyclobutane Thymine Dimer.

    Science.gov (United States)

    Mendieta-Moreno, Jesús I; Trabada, Daniel G; Mendieta, Jesús; Lewis, James P; Gómez-Puertas, Paulino; Ortega, José

    2016-11-03

    The absorption of ultraviolet radiation by DNA may result in harmful genetic lesions that affect DNA replication and transcription, ultimately causing mutations, cancer, and/or cell death. We analyze the most abundant photochemical reaction in DNA, the cyclobutane thymine dimer, using hybrid quantum mechanics/molecular mechanics (QM/MM) techniques and QM/MM nonadiabatic molecular dynamics. We find that, due to its double helix structure, DNA presents a free energy barrier between nonreactive and reactive conformations leading to the photolesion. Moreover, our nonadiabatic simulations show that most of the photoexcited reactive conformations return to standard B-DNA conformations after an ultrafast nonradiative decay to the ground state. This work highlights the importance of dynamical effects (free energy, excited-state dynamics) for the study of photochemical reactions in biological systems.

  12. Quantum chemical molecular dynamical investigation of alkyl nitrite photo-dissociated on copper surfaces

    International Nuclear Information System (INIS)

    Wang Xiaojing; Wang Wei; Han Peilin; Kubo, Momoji; Miyamoto, Akira

    2008-01-01

    An accelerated quantum chemical molecular dynamical code 'Colors-Excite' was used to investigate the photolysis of alkyl nitrites series, RONO (R=CH 3 and C(CH 3 ) 3 ) on copper surfaces. Our calculations showed that the photo-dissociated processes are associated with the alkyl substituents of RONO when adsorbed on copper surfaces. For R=CH 3 , a two-step photolysis reaction occurred, yielding diverse intermediate products including RO radical, NO, and HNO, consistent with those reported in gas phase. While for R=C(CH 3 ) 3 , only one-step photolysis reaction occurred and gave intermediate products of RO radical and NO. Consequently, pure RO species were achieved to adsorb on metal surfaces by removing the NO species in photolysis reaction. The detailed photo-dissociated behaviors of RONO on copper surfaces with different alkyl substituents which are uncovered by the present simulation can be extended to explain the diverse dissociative mechanism experimentally observed. The quantum chemical molecular dynamical code 'Colors-Excite' is proved to be highly applicable to the photo-dissociations on metal surfaces

  13. Quantum dynamics of fast chemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Light, J.C. [Univ. of Chicago, IL (United States)

    1993-12-01

    The aims of this research are to explore, develop, and apply theoretical methods for the evaluation of the dynamics of gas phase collision processes, primarily chemical reactions. The primary theoretical tools developed for this work have been quantum scattering theory, both in time dependent and time independent forms. Over the past several years, the authors have developed and applied methods for the direct quantum evaluation of thermal rate constants, applying these to the evaluation of the hydrogen isotopic exchange reactions, applied wave packet propagation techniques to the dissociation of Rydberg H{sub 3}, incorporated optical potentials into the evaluation of thermal rate constants, evaluated the use of optical potentials for state-to-state reaction probability evaluations, and, most recently, have developed quantum approaches for electronically non-adiabatic reactions which may be applied to simplify calculations of reactive, but electronically adiabatic systems. Evaluation of the thermal rate constants and the dissociation of H{sub 3} were reported last year, and have now been published.

  14. Unified semiclassical theory for the two-state system: an analytical solution for general nonadiabatic tunneling.

    Science.gov (United States)

    Zhu, Chaoyuan; Lin, Sheng Hsien

    2006-07-28

    Unified semiclasical solution for general nonadiabatic tunneling between two adiabatic potential energy surfaces is established by employing unified semiclassical solution for pure nonadiabatic transition [C. Zhu, J. Chem. Phys. 105, 4159 (1996)] with the certain symmetry transformation. This symmetry comes from a detailed analysis of the reduced scattering matrix for Landau-Zener type of crossing as a special case of nonadiabatic transition and nonadiabatic tunneling. Traditional classification of crossing and noncrossing types of nonadiabatic transition can be quantitatively defined by the rotation angle of adiabatic-to-diabatic transformation, and this rotational angle enters the analytical solution for general nonadiabatic tunneling. The certain two-state exponential potential models are employed for numerical tests, and the calculations from the present general nonadiabatic tunneling formula are demonstrated in very good agreement with the results from exact quantum mechanical calculations. The present general nonadiabatic tunneling formula can be incorporated with various mixed quantum-classical methods for modeling electronically nonadiabatic processes in photochemistry.

  15. A design study of non-adiabatic electron guns

    International Nuclear Information System (INIS)

    Barroso, J.J.; Stellati, C.

    1994-01-01

    The design of a non-adiabatic gun capable of producing a 10 A, 50 KeV high-quality laminar electron beam is reported. In contrast to the magnetron injection gun with a conical cathode, where the beam is generated initially with a transverse velocity component, in the non-adiabatic gun electrons are extracted in a direction parallel to the axial guide magnetic field. The beam electrons acquire cyclotron motion as result of non-adiabatic processes in a strong non uniform electric field across the modulation anode. Such an extraction method gives rise to favourable features that are explored throughout the work. An extensive numerical simulation study has also been done to minimize velocity and energy spreads. (author). 3 refs, 5 figs, 1 tab

  16. Unraveling nonadiabatic ionization and Coulomb potential effect in strong-field photoelectron holography.

    Science.gov (United States)

    Song, Xiaohong; Lin, Cheng; Sheng, Zhihao; Liu, Peng; Chen, Zhangjin; Yang, Weifeng; Hu, Shilin; Lin, C D; Chen, Jing

    2016-06-22

    Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system. After ionization, part of the electron wave packet may directly go to the detector (the reference wave), while another part may be driven back and scatters off the ion(the signal wave). The interference hologram of the two waves may be used to extract target information embedded in the collision process. Unlike conventional optical holography, however, propagation of the electron wave packet is affected by the Coulomb potential as well as by the laser field. In addition, electrons are emitted over the whole laser pulse duration, thus multiple interferences may occur. In this work, we used a generalized quantum-trajectory Monte Carlo method to investigate the effect of Coulomb potential and the nonadiabatic subcycle ionization on the photoelectron hologram. We showed that photoelectron hologram can be well described only when the effect of nonadiabatic ionization is accounted for, and Coulomb potential can be neglected only in the tunnel ionization regime. Our results help paving the way for establishing photoelectron holography for probing spatial and dynamic properties of atoms and molecules.

  17. Excited state non-adiabatic dynamics of the smallest polyene, trans 1,3-butadiene. I. Time-resolved photoelectron-photoion coincidence spectroscopy

    Science.gov (United States)

    Boguslavskiy, Andrey E.; Schalk, Oliver; Gador, Niklas; Glover, William J.; Mori, Toshifumi; Schultz, Thomas; Schuurman, Michael S.; Martínez, Todd J.; Stolow, Albert

    2018-04-01

    The ultrafast excited state dynamics of the smallest polyene, trans-1,3-butadiene, were studied by femtosecond time-resolved photoelectron-photoion coincidence (TRPEPICO) spectroscopy. The evolution of the excited state wavepacket, created by pumping the bright 1Bu (ππ*) electronic state at its origin of 216 nm, is projected via one- and two-photon ionization at 267 nm onto several ionization continua. The results are interpreted in terms of Koopmans' correlations and Franck-Condon factors for the excited and cationic states involved. The known predissociative character of the cation excited states is utilized to assign photoelectron bands to specific continua using TRPEPICO spectroscopy. This permits us to report the direct observation of the famously elusive S1(21Ag) dark electronic state during the internal conversion of trans 1,3-butadiene. Our phenomenological analysis permits the spectroscopic determination of several important time constants. We report the overall decay lifetimes of the 11Bu and 21Ag states and observe the re-appearance of the hot ground state molecule. We argue that the apparent dephasing time of the S2(11Bu) state, which leads to the extreme breadth of the absorption spectrum, is principally due to large amplitude torsional motion on the 1Bu surface in conjunction with strong non-adiabatic couplings via conical intersections, whereupon nuclear wavepacket revivals to the initial Franck-Condon region become effectively impossible. In Paper II [W. J. Glover et al., J. Chem. Phys. 148, 164303 (2018)], ab initio multiple spawning is used for on-the-fly computations of the excited state non-adiabatic wavepacket dynamics and their associated TRPEPICO observables, allowing for direct comparisons of experiment with theory.

  18. Dissociation of polycyclic aromatic hydrocarbons: molecular dynamics studies

    Science.gov (United States)

    Simon, A.; Rapacioli, M.; Rouaut, G.; Trinquier, G.; Gadéa, F. X.

    2017-03-01

    We present dynamical studies of the dissociation of polycyclic aromatic hydrocarbon (PAH) radical cations in their ground electronic states with significant internal energy. Molecular dynamics simulations are performed, the electronic structure being described on-the-fly at the self-consistent-charge density functional-based tight binding (SCC-DFTB) level of theory. The SCC-DFTB approach is first benchmarked against DFT results. Extensive simulations are achieved for naphthalene , pyrene and coronene at several energies. Such studies enable one to derive significant trends on branching ratios, kinetics, structures and hints on the formation mechanism of the ejected neutral fragments. In particular, dependence of branching ratios on PAH size and energy were retrieved. The losses of H and C2H2 (recognized as the ethyne molecule) were identified as major dissociation channels. The H/C2H2 ratio was found to increase with PAH size and to decrease with energy. For , which is the most interesting PAH from the astrophysical point of view, the loss of H was found as the quasi-only channel for an internal energy of 30 eV. Overall, in line with experimental trends, decreasing the internal energy or increasing the PAH size will favour the hydrogen loss channels with respect to carbonaceous fragments. This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'.

  19. Emission spectroscopic studies on dynamics of molecular excitation and dissociation by controlled electron impact

    International Nuclear Information System (INIS)

    Ogawa, Teiichiro

    1986-01-01

    Emission spectrum by controlled electron impact has been a successful technique for the investigation of molecular dynamics. (1) Molecular excitation. Aromatic molecules give an optical emission similar to fluorescence. However, as is shown by the vibrational structure and the electron energy dependence of benzene emission, its excitation process is not necessarily optical. Some aliphatic molecules also exhibit an emission band at the ultraviolet region. (2) Molecular dissociation. Analysis of the Doppler profile, the threshold energy, the excitation function and the isotope effect of the atomic emission produced in electron-molecule collisions has clarified the dynamics of the molecular dissociation. Especially the Doppler profile has given the translational energy distribution of the fragment atom, which is very useful to disclose the potential energy curve. Its angular dependence has recently found to allow determination of the symmetry of the intermediate excited state and the magnetic sublevel distribution of the fragment atom. These finding has revealed detailed state-to-state dynamics of the molecular dissociation. (author)

  20. Levitation of Bose-Einstein condensates induced by macroscopic non-adiabatic quantum tunneling

    OpenAIRE

    Nakamura, Katsuhiro; Kohi, Akihisa; Yamasaki, Hisatsugu; Perez-Garcia, Victor M.

    2006-01-01

    We study the dynamics of two-component Bose-Einstein condensates trapped in different vertical positions in the presence of an oscillating magnetic field. It is shown here how tuning appropriately the oscillation frequency of the magnetic field leads to the levitation of the system against gravity. This phenomenon is a manifestation of a macroscopic non-adiabatic tunneling in a system with internal degrees of freedom.

  1. Nuclear quantum effects on the nonadiabatic decay mechanism of an excited hydrated electron

    Science.gov (United States)

    Borgis, Daniel; Rossky, Peter J.; Turi, László

    2007-11-01

    We present a kinetic analysis of the nonadiabatic decay mechanism of an excited state hydrated electron to the ground state. The theoretical treatment is based on a quantized, gap dependent golden rule rate constant formula which describes the nonadiabatic transition rate between two quantum states. The rate formula is expressed in terms of quantum time correlation functions of the energy gap and of the nonadiabatic coupling. These gap dependent quantities are evaluated from three different sets of mixed quantum-classical molecular dynamics simulations of a hydrated electron equilibrated (a) in its ground state, (b) in its first excited state, and (c) on a hypothetical mixed potential energy surface which is the average of the ground and the first excited electronic states. The quantized, gap dependent rate results are applied in a phenomenological kinetic equation which provides the survival probability function of the excited state electron. Although the lifetime of the equilibrated excited state electron is computed to be very short (well under 100fs), the survival probability function for the nonequilibrium process in pump-probe experiments yields an effective excited state lifetime of around 300fs, a value that is consistent with the findings of several experimental groups and previous theoretical estimates.

  2. Dynamics of infrared multiphonon dissociation of SF6 by molecular beam method

    International Nuclear Information System (INIS)

    Grant, E.R.; Coggiola, M.J.; Lee, Y.T.; Schulz, P.A.; Shen, Y.R.

    1977-01-01

    A crossed molecular beam apparatus has been adapted to study the dynamics of excitation and dissociation of polyatomic molecules in intense IR laser fields. Initial experiments have involved the study of the dissociation of SF 6 by CO 2 laser radiation at 10.6 μm. A molecular beam of SF 6 was formed by supersonic expansion using three stages of differential pumping. A grating tuned pulsed CO 2 TEA laser was used as the excitation source. The laser beam was focused by a 25 cm focal length ZnSe lens, and crossed the molecular beam near its focal point. The fragments produced by multiphonon dissociation of SF 6 within the small interaction region were detected as a function of recoil angle and velocity. (Auth.)

  3. Nonadiabatic optical transitions as a turn-on switch for pulse shaping

    International Nuclear Information System (INIS)

    Hashmi, F. A.; Bouchene, M. A.

    2010-01-01

    A strong nonresonant, asymmetric ultrashort pulse drives an atomic transition and causes a complete population inversion because of a sudden nonadiabatic jump. This jump is probed in real time by propagating a weak ultrashort pulse in the system which is resonant on an adjacent transition. The probe at the exit of the medium presents an oscillatory structure with the nonadiabatic jump marked in time by the onset of oscillations. The nonadiabatic jump thus acts as a 'turn-on' switch for the shaping of the probe.

  4. Ionization and dissociation dynamics of vinyl bromide probed by femtosecond extreme ultraviolet transient absorption spectroscopy

    International Nuclear Information System (INIS)

    Lin, Ming-Fu; Neumark, Daniel M.; Gessner, Oliver; Leone, Stephen R.

    2014-01-01

    Strong-field induced ionization and dissociation dynamics of vinyl bromide, CH 2 =CHBr, are probed using femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy. Strong-field ionization is initiated with an intense femtosecond, near infrared (NIR, 775 nm) laser field. Femtosecond XUV pulses covering the photon energy range of 50-72 eV probe the subsequent dynamics by measuring the time-dependent spectroscopic features associated with transitions of the Br (3d) inner-shell electrons to vacancies in molecular and atomic valence orbitals. Spectral signatures are observed for the depletion of neutral C 2 H 3 Br, the formation of C 2 H 3 Br + ions in their ground (X ~ ) and first excited (A ~ ) states, the production of C 2 H 3 Br ++ ions, and the appearance of neutral Br ( 2 P 3/2 ) atoms by dissociative ionization. The formation of free Br ( 2 P 3/2 ) atoms occurs on a timescale of 330 ± 150 fs. The ionic A ~ state exhibits a time-dependent XUV absorption energy shift of ∼0.4 eV within the time window of the atomic Br formation. The yield of Br atoms correlates with the yield of parent ions in the A ~ state as a function of NIR peak intensity. The observations suggest that a fraction of vibrationally excited C 2 H 3 Br + (A ~ ) ions undergoes intramolecular vibrational energy redistribution followed by the C–Br bond dissociation. The C 2 H 3 Br + (X ~ ) products and the majority of the C 2 H 3 Br ++ ions are relatively stable due to a deeper potential well and a high dissociation barrier, respectively. The results offer powerful new insights about orbital-specific electronic processes in high field ionization, coupled vibrational relaxation and dissociation dynamics, and the correlation of valence hole-state location and dissociation in polyatomic molecules, all probed simultaneously by ultrafast table-top XUV spectroscopy

  5. Taming the escape dynamics of nonadiabatic time-periodically driven quantum dissipative system within the frame of Wigner formalism

    Energy Technology Data Exchange (ETDEWEB)

    Shit, Anindita [Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Chattopadhyay, Sudip, E-mail: sudip_chattopadhyay@rediffmail.com [Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Ray Chaudhuri, Jyotipratim, E-mail: jprc_8@yahoo.com [Department of Physics, Katwa College, Katwa, Burdwan 713130 (India)

    2014-03-18

    Highlights: • Nonadiabatic dynamics of quantum particle under the impact of high-frequency force. • Formulation of time-independent dynamics via Floquet and Kapitza schemes. • Manipulation of external force parameters allows us to control the escape rate. • Increase of (amplitudes/frequency) causes the system to decay faster, in general. • Crossover temperature increases in the presence of the field. - Abstract: Escape under the action of the external modulation constitutes a nontrivial generalization of an conventional Kramers rate because the system is away from thermal equilibrium. A derivation of this result from the point of view of Langevin dynamics in the frame of Floquet theorem in conjunction with the Kapitza–Landau time window (that leads to an attractive description of the time-dependent quantum dynamics in terms of time-independent one) has been provided. The quantum escape rate in the intermediate-to-high and very-high damping regime so obtained analytically using the phase space formalism associated with the Wigner distribution and path-integral formalism bears a quantum correction that depends strongly on the barrier height. It is shown that an increase of (amplitude/frequency) ratio causes the system to decay faster, in general. The crossover temperature between tunneling and thermal activation increases in the presence of field so that quantum effects in the escape are relevant at higher temperatures.

  6. Multiscale approach combining nonadiabatic dynamics with long-time radiative and non-radiative decay: Dissociative ionization of heavy rare-gas tetramers revisited

    Czech Academy of Sciences Publication Activity Database

    Janeček, Ivan; Janča, T.; Naar, P.; Kalus, R.; Gadéa, F. X.

    2013-01-01

    Roč. 138, č. 4 (2013), s. 1-12 ISSN 0021-9606 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : atomic clusters * electromagnetic decays * electron impact dissociation * electron impact ionisation * isomerism * krypton * nonradiative transitions * xenon Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.122, year: 2013 http://jcp.aip.org/resource/1/jcpsa6/v138/i4/p044303_s1?isAuthorized=no

  7. Nonequilibrium Green's function theory for nonadiabatic effects in quantum electron transport

    Science.gov (United States)

    Kershaw, Vincent F.; Kosov, Daniel S.

    2017-12-01

    We develop nonequilibrium Green's function-based transport theory, which includes effects of nonadiabatic nuclear motion in the calculation of the electric current in molecular junctions. Our approach is based on the separation of slow and fast time scales in the equations of motion for Green's functions by means of the Wigner representation. Time derivatives with respect to central time serve as a small parameter in the perturbative expansion enabling the computation of nonadiabatic corrections to molecular Green's functions. Consequently, we produce a series of analytic expressions for non-adiabatic electronic Green's functions (up to the second order in the central time derivatives), which depend not solely on the instantaneous molecular geometry but likewise on nuclear velocities and accelerations. An extended formula for electric current is derived which accounts for the non-adiabatic corrections. This theory is concisely illustrated by the calculations on a model molecular junction.

  8. Photodissociation dynamics of CH3C(O)SH in argon matrix: A QM/MM nonadiabatic dynamics simulation

    Science.gov (United States)

    Xia, Shu-Hua; Liu, Xiang-Yang; Fang, Qiu; Cui, Ganglong

    2015-11-01

    In this work, we have first employed the combined quantum mechanics/molecular mechanics (QM/MM) method to study the photodissociation mechanism of thioacetic acid CH3C(O)SH in the S1, T1, and S0 states in argon matrix. CH3C(O)SH is treated quantum mechanically using the complete active space self-consistent field and complete active space second-order perturbation theory methods; argon matrix is described classically using Lennard-Jones potentials. We find that the C-S bond fission is predominant due to its small barriers of ca. 3.0 and 1.0 kcal/mol in the S1 and T1 states. It completely suppresses the nearby C—C bond fission. After the bond fission, the S1 radical pair of CH3CO and SH can decay to the S0 and T1 states via internal conversion and intersystem crossing, respectively. In the S0 state, the radical pair can either recombine to form CH3C(O)SH or proceed to form molecular products of CH2CO and H2S. We have further employed our recently developed QM/MM generalized trajectory-based surface-hopping method to simulate the photodissociation dynamics of CH3C(O)SH. In 1 ps dynamics simulation, 56% trajectories stay at the Franck-Condon region; the S1 C—S bond fission takes place in the remaining 44% trajectories. Among all nonadiabatic transitions, the S1 → S0 internal conversion is major (55%) but the S1 → T1 intersystem crossing is still comparable and cannot be ignored, which accounts for 28%. Finally, we have found a radical channel generating the molecular products of CH2CO and H2S, which is complementary to the concerted molecular channel. The present work sets the stage for simulating photodissociation dynamics of similar thio-carbonyl systems in matrix.

  9. Franck--Condon factors in studies of dynamics of chemical reactions. IV. Nonadiabatic collisions

    International Nuclear Information System (INIS)

    Zvijac, D.J.; Ross, J.

    1978-01-01

    We investigate the application of the Franck--Condon approach to nonadiabatic molecular scattering processes. Computationally simple, analytic formulas are developed to describe the energy dependence of quenching of electronically excited atoms by atoms and molecules. These formulas include the dependence of the Franck--Condon factors on the translational wavefunctions as well as the wavefunctions for the internal degrees of freedom. We use these formulas to evaluate the translational energy dependence of the fine structure transition cross sections for F( 2 P/sub 3/2/)+X→F( 2 P/sub 1/2/)+X, where X= Xe, H + , and H 2 . The cross sections generally increase as the initial translational energy increases. Our results agree semiquantiatively (or better) with those obtained from other theoretical techniques. In the case of F+H + we find that the absolute cross section is sensitive to the analytic form used for the nonadiabatic coupling but our model gives the correct energy dependence. At the energies of our calculations we find only a small amount of vibrational excitation of H 2 . Finally, we use our expressions to interpret some trends of available experimental results on the quenching of Hg ( 3 P 2 → 3 P 1 ) by several molecules. We find that collisional excitation of the internal modes of the molecule becomes more important as the initial translational energy increases. However, these modes do not contribute to the quenching cross section in a statistical fashion

  10. Water dissociating on rigid Ni(100): A quantum dynamics study on a full-dimensional potential energy surface

    Science.gov (United States)

    Liu, Tianhui; Chen, Jun; Zhang, Zhaojun; Shen, Xiangjian; Fu, Bina; Zhang, Dong H.

    2018-04-01

    We constructed a nine-dimensional (9D) potential energy surface (PES) for the dissociative chemisorption of H2O on a rigid Ni(100) surface using the neural network method based on roughly 110 000 energies obtained from extensive density functional theory (DFT) calculations. The resulting PES is accurate and smooth, based on the small fitting errors and the good agreement between the fitted PES and the direct DFT calculations. Time dependent wave packet calculations also showed that the PES is very well converged with respect to the fitting procedure. The dissociation probabilities of H2O initially in the ground rovibrational state from 9D quantum dynamics calculations are quite different from the site-specific results from the seven-dimensional (7D) calculations, indicating the importance of full-dimensional quantum dynamics to quantitatively characterize this gas-surface reaction. It is found that the validity of the site-averaging approximation with exact potential holds well, where the site-averaging dissociation probability over 15 fixed impact sites obtained from 7D quantum dynamics calculations can accurately approximate the 9D dissociation probability for H2O in the ground rovibrational state.

  11. Collision-induced dissociation of diatomic ions

    International Nuclear Information System (INIS)

    Los, J.; Govers, T.R.

    1978-01-01

    An attempt is made to illustrate how mass spectrometric studies of dissociation in diatomic molecular ions can provide information on the dynamics of these collisions and on the predissociative states involved. Restriction is made to primary beam energies of the order of at least keV. The review covers the dynamics of dissociation, experimental techniques, direct dissociation in heavy-particle collisions, and translational spectroscopy. 120 references

  12. Ideal quantum gas in an expanding cavity: nature of nonadiabatic force.

    Science.gov (United States)

    Nakamura, K; Avazbaev, S K; Sobirov, Z A; Matrasulov, D U; Monnai, T

    2011-04-01

    We consider a quantum gas of noninteracting particles confined in the expanding cavity and investigate the nature of the nonadiabatic force which is generated from the gas and acts on the cavity wall. First, with use of the time-dependent canonical transformation, which transforms the expanding cavity to the nonexpanding one, we can define the force operator. Second, applying the perturbative theory, which works when the cavity wall begins to move at time origin, we find that the nonadiabatic force is quadratic in the wall velocity and thereby does not break the time-reversal symmetry, in contrast with general belief. Finally, using an assembly of the transitionless quantum states, we obtain the nonadiabatic force exactly. The exact result justifies the validity of both the definition of the force operator and the issue of the perturbative theory. The mysterious mechanism of nonadiabatic transition with the use of transitionless quantum states is also explained. The study is done for both cases of the hard- and soft-wall confinement with the time-dependent confining length. ©2011 American Physical Society

  13. Evidence for stepwise dissociation dynamics in acetone at 248 and 193 nm

    Science.gov (United States)

    North, Simon W.; Blank, David A.; Gezelter, J. Daniel; Longfellow, Cheryl A.; Lee, Yuan T.

    1995-03-01

    The technique of molecular beam photofragment translational spectroscopy has been used to study the dissociation of acetone following S1←S0 (248 nm) and S2←S0 (193 nm) excitation. Excitation at 248 nm resulted in the production of CH3 and CH3CO with 14.2±1.0 kcal/mole on average of the available energy appearing as translation of the photofragments. Comparison of the measured with values reported at 266 nm suggest that the energy partitioning is dominated by the exit barrier caused by an avoided crossing on the potential energy surface. A substantial fraction (30±4%) of the nascent acetyl radicals from the primary dissociation contain sufficient energy to undergo spontaneous secondary decomposition. From the onset of the truncation of the CH3CO P(ET) a threshold of 17.8±3.0 kcal/mole for the dissociation of the acetyl radical has been determined in agreement with recent results on the photodissociation of acetyl chloride. The translational energy release in the dissociation of CH3CO closely matches the experimentally determined exit barrier. At 193 nm the only observed dissociation pathway was the formation of two methyl radicals and carbon monoxide. On average ˜38% of the available energy is found in product translation suggesting that significant internal energy resides in the nascent CH3 fragments consistent with the results of Hall et al. [J. Chem. Phys. 94, 4182 (1991)]. We conclude that the dynamics and energy partitioning for dissociation at 193 nm is similar to that at 248 nm.

  14. Plasma Jet Braking: Energy Dissipation and Nonadiabatic Electrons

    International Nuclear Information System (INIS)

    Khotyaintsev, Yu. V.; Cully, C. M.; Vaivads, A.; Andre, M.; Owen, C. J.

    2011-01-01

    We report in situ observations by the Cluster spacecraft of wave-particle interactions in a magnetic flux pileup region created by a magnetic reconnection outflow jet in Earth's magnetotail. Two distinct regions of wave activity are identified: lower-hybrid drift waves at the front edge and whistler-mode waves inside the pileup region. The whistler-mode waves are locally generated by the electron temperature anisotropy, and provide evidence for ongoing betatron energization caused by magnetic flux pileup. The whistler-mode waves cause fast pitch-angle scattering of electrons and isotropization of the electron distribution, thus making the flow braking process nonadiabatic. The waves strongly affect the electron dynamics and thus play an important role in the energy conversion chain during plasma jet braking.

  15. Photodissociation dynamics of CH{sub 3}C(O)SH in argon matrix: A QM/MM nonadiabatic dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Shu-Hua; Liu, Xiang-Yang; Fang, Qiu; Cui, Ganglong, E-mail: ganglong.cui@bnu.edu.cn [Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875 (China)

    2015-11-21

    In this work, we have first employed the combined quantum mechanics/molecular mechanics (QM/MM) method to study the photodissociation mechanism of thioacetic acid CH{sub 3}C(O)SH in the S{sub 1}, T{sub 1}, and S{sub 0} states in argon matrix. CH{sub 3}C(O)SH is treated quantum mechanically using the complete active space self-consistent field and complete active space second-order perturbation theory methods; argon matrix is described classically using Lennard-Jones potentials. We find that the C-S bond fission is predominant due to its small barriers of ca. 3.0 and 1.0 kcal/mol in the S{sub 1} and T{sub 1} states. It completely suppresses the nearby C—C bond fission. After the bond fission, the S{sub 1} radical pair of CH{sub 3}CO and SH can decay to the S{sub 0} and T{sub 1} states via internal conversion and intersystem crossing, respectively. In the S{sub 0} state, the radical pair can either recombine to form CH{sub 3}C(O)SH or proceed to form molecular products of CH{sub 2}CO and H{sub 2}S. We have further employed our recently developed QM/MM generalized trajectory-based surface-hopping method to simulate the photodissociation dynamics of CH{sub 3}C(O)SH. In 1 ps dynamics simulation, 56% trajectories stay at the Franck-Condon region; the S{sub 1} C—S bond fission takes place in the remaining 44% trajectories. Among all nonadiabatic transitions, the S{sub 1} → S{sub 0} internal conversion is major (55%) but the S{sub 1} → T{sub 1} intersystem crossing is still comparable and cannot be ignored, which accounts for 28%. Finally, we have found a radical channel generating the molecular products of CH{sub 2}CO and H{sub 2}S, which is complementary to the concerted molecular channel. The present work sets the stage for simulating photodissociation dynamics of similar thio-carbonyl systems in matrix.

  16. Intrinsic nonadiabatic topological torque in magnetic skyrmions and vortices

    KAUST Repository

    Akosa, Collins Ashu; Ndiaye, Papa Birame; Manchon, Aurelien

    2017-01-01

    We propose that topological spin currents flowing in topologically nontrivial magnetic textures, such as magnetic skyrmions and vortices, produce an intrinsic nonadiabatic torque of the form Tt∼[(∂xm×∂ym)·m]∂ym. We show that this torque, which is absent in one-dimensional domain walls and/or nontopological textures, is responsible for the enhanced nonadiabaticity parameter observed in magnetic vortices compared to one-dimensional textures. The impact of this torque on the motion of magnetic skyrmions is expected to be crucial, especially to determine their robustness against defects and pinning centers.

  17. Intrinsic nonadiabatic topological torque in magnetic skyrmions and vortices

    KAUST Repository

    Akosa, Collins Ashu

    2017-03-01

    We propose that topological spin currents flowing in topologically nontrivial magnetic textures, such as magnetic skyrmions and vortices, produce an intrinsic nonadiabatic torque of the form Tt∼[(∂xm×∂ym)·m]∂ym. We show that this torque, which is absent in one-dimensional domain walls and/or nontopological textures, is responsible for the enhanced nonadiabaticity parameter observed in magnetic vortices compared to one-dimensional textures. The impact of this torque on the motion of magnetic skyrmions is expected to be crucial, especially to determine their robustness against defects and pinning centers.

  18. Excited state non-adiabatic dynamics of N-methylpyrrole: A time-resolved photoelectron spectroscopy and quantum dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Guorong [National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada); State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023 (China); Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Neville, Simon P. [Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5 (Canada); Schalk, Oliver [National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada); Department of Physics, AlbaNova University Center, Stockholm University, Roslagstullsbacken 21, 106 91 Stockholm (Sweden); Sekikawa, Taro [Department of Applied Physics, Hokkaido University, Kita-13 Nishi-8, Kita-ku, Sapporo 060-8628 (Japan); Ashfold, Michael N. R. [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Worth, Graham A. [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Stolow, Albert, E-mail: astolow@uottawa.ca [National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada); Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5 (Canada); Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada)

    2016-01-07

    The dynamics of N-methylpyrrole following excitation at wavelengths in the range 241.5-217.0 nm were studied using a combination of time-resolved photoelectron spectroscopy (TRPES), ab initio quantum dynamics calculations using the multi-layer multi-configurational time-dependent Hartree method, as well as high-level photoionization cross section calculations. Excitation at 241.5 and 236.2 nm results in population of the A{sub 2}(πσ{sup ∗}) state, in agreement with previous studies. Excitation at 217.0 nm prepares the previously neglected B{sub 1}(π3p{sub y}) Rydberg state, followed by prompt internal conversion to the A{sub 2}(πσ{sup ∗}) state. In contrast with the photoinduced dynamics of pyrrole, the lifetime of the wavepacket in the A{sub 2}(πσ{sup ∗}) state was found to vary with excitation wavelength, decreasing by one order of magnitude upon tuning from 241.5 nm to 236.2 nm and by more than three orders of magnitude when excited at 217.0 nm. The order of magnitude difference in lifetimes measured at the longer excitation wavelengths is attributed to vibrational excitation in the A{sub 2}(πσ{sup ∗}) state, facilitating wavepacket motion around the potential barrier in the N–CH{sub 3} dissociation coordinate.

  19. Excited state non-adiabatic dynamics of N-methylpyrrole: A time-resolved photoelectron spectroscopy and quantum dynamics study

    International Nuclear Information System (INIS)

    Wu, Guorong; Neville, Simon P.; Schalk, Oliver; Sekikawa, Taro; Ashfold, Michael N. R.; Worth, Graham A.; Stolow, Albert

    2016-01-01

    The dynamics of N-methylpyrrole following excitation at wavelengths in the range 241.5-217.0 nm were studied using a combination of time-resolved photoelectron spectroscopy (TRPES), ab initio quantum dynamics calculations using the multi-layer multi-configurational time-dependent Hartree method, as well as high-level photoionization cross section calculations. Excitation at 241.5 and 236.2 nm results in population of the A 2 (πσ ∗ ) state, in agreement with previous studies. Excitation at 217.0 nm prepares the previously neglected B 1 (π3p y ) Rydberg state, followed by prompt internal conversion to the A 2 (πσ ∗ ) state. In contrast with the photoinduced dynamics of pyrrole, the lifetime of the wavepacket in the A 2 (πσ ∗ ) state was found to vary with excitation wavelength, decreasing by one order of magnitude upon tuning from 241.5 nm to 236.2 nm and by more than three orders of magnitude when excited at 217.0 nm. The order of magnitude difference in lifetimes measured at the longer excitation wavelengths is attributed to vibrational excitation in the A 2 (πσ ∗ ) state, facilitating wavepacket motion around the potential barrier in the N–CH 3 dissociation coordinate

  20. Spatial non-adiabatic passage using geometric phases

    Energy Technology Data Exchange (ETDEWEB)

    Benseny, Albert; Busch, Thomas [Okinawa Institute of Science and Technology Graduate University, Quantum Systems Unit, Okinawa (Japan); Kiely, Anthony; Ruschhaupt, Andreas [University College Cork, Department of Physics, Cork (Ireland); Zhang, Yongping [Okinawa Institute of Science and Technology Graduate University, Quantum Systems Unit, Okinawa (Japan); Shanghai University, Department of Physics, Shanghai (China)

    2017-12-15

    Quantum technologies based on adiabatic techniques can be highly effective, but often at the cost of being very slow. Here we introduce a set of experimentally realistic, non-adiabatic protocols for spatial state preparation, which yield the same fidelity as their adiabatic counterparts, but on fast timescales. In particular, we consider a charged particle in a system of three tunnel-coupled quantum wells, where the presence of a magnetic field can induce a geometric phase during the tunnelling processes. We show that this leads to the appearance of complex tunnelling amplitudes and allows for the implementation of spatial non-adiabatic passage. We demonstrate the ability of such a system to transport a particle between two different wells and to generate a delocalised superposition between the three traps with high fidelity in short times. (orig.)

  1. Complex-valued derivative propagation method with approximate Bohmian trajectories: Application to electronic nonadiabatic dynamics

    Science.gov (United States)

    Wang, Yu; Chou, Chia-Chun

    2018-05-01

    The coupled complex quantum Hamilton-Jacobi equations for electronic nonadiabatic transitions are approximately solved by propagating individual quantum trajectories in real space. Equations of motion are derived through use of the derivative propagation method for the complex actions and their spatial derivatives for wave packets moving on each of the coupled electronic potential surfaces. These equations for two surfaces are converted into the moving frame with the same grid point velocities. Excellent wave functions can be obtained by making use of the superposition principle even when nodes develop in wave packet scattering.

  2. Nonadiabatic Response Model of Laser-Induced Ultrafast π-Electron Rotations in Chiral Aromatic Molecules

    International Nuclear Information System (INIS)

    Kanno, Manabu; Kono, Hirohiko; Fujimura, Yuichi; Lin, Sheng H.

    2010-01-01

    We theoretically investigated the nonadiabatic couplings between optically induced π-electron rotations and molecular vibrations in a chiral aromatic molecule irradiated by a nonhelical, linearly polarized laser pulse. The results of wave packet dynamics simulation show that the vibrational amplitudes strongly depend on the initial rotation direction, clockwise or counterclockwise, which is controlled by the polarization direction of the incident pulse. This suggests that attosecond π-electron rotations can be observed by spectroscopic detection of femtosecond molecular vibrations.

  3. Topology of a dissipative spin: Dynamical Chern number, bath-induced nonadiabaticity, and a quantum dynamo effect

    Science.gov (United States)

    Henriet, Loïc; Sclocchi, Antonio; Orth, Peter P.; Le Hur, Karyn

    2017-02-01

    We analyze the topological deformations of the ground state manifold of a quantum spin-1/2 in a magnetic field H =H (sinθ cosϕ ,sinθ sinϕ ,cosθ ) induced by a coupling to an ohmic quantum dissipative environment at zero temperature. From Bethe ansatz results and a variational approach, we confirm that the Chern number associated with the geometry of the reduced spin ground state manifold is preserved in the delocalized phase for α <1 . We report a divergence of the Berry curvature at αc=1 for magnetic fields aligned along the equator θ =π /2 . This divergence is caused by the complete quenching of the transverse magnetic field by the bath associated with a gap closing that occurs at the localization Kosterlitz-Thouless quantum phase transition in this model. Recent experiments in quantum circuits have engineered nonequilibrium protocols to access topological properties from a measurement of a dynamical Chern number defined via the out-of-equilibrium spin expectation values. Applying a numerically exact stochastic Schrödinger approach we find that, for a fixed field sweep velocity θ (t )=v t , the bath induces a crossover from (quasi)adiabatic to nonadiabatic dynamical behavior when the spin bath coupling α increases. We also investigate the particular regime H /ωc≪v /H ≪1 with large bath cutoff frequency ωc, where the dynamical Chern number vanishes already at α =1 /2 . In this regime, the mapping to an interacting resonance level model enables us to analytically describe the behavior of the dynamical Chern number in the vicinity of α =1 /2 . We further provide an intuitive physical explanation of the bath-induced breakdown of adiabaticity in analogy to the Faraday effect in electromagnetism. We demonstrate that the driving of the spin leads to the production of a large number of bosonic excitations in the bath, which strongly affect the spin dynamics. Finally, we quantify the spin-bath entanglement and formulate an analogy with an effective

  4. Nonadiabatic electron response in the Hasegawa-Wakatani equations

    International Nuclear Information System (INIS)

    Stoltzfus-Dueck, T.; Scott, B. D.; Krommes, J. A.

    2013-01-01

    Tokamak edge turbulence is strongly influenced by parallel electron physics, which relaxes density and potential fluctuations towards electron adiabatic response. Beginning with the paradigmatic Hasegawa-Wakatani equations (HWEs) for resistive tokamak edge turbulence, a unique decomposition of the electric potential (φ) into adiabatic (a) and nonadiabatic (b) portions is derived, based on the requirement that a neither drive nor respond to the parallel current j ∥ . The form of the decomposition clarifies that, at perpendicular scales large relative to the sound radius, the electron adiabatic response controls the nonzonal φ, not the fluctuating density n. Simple energy balance arguments allow one to rigorously bound the ratio of rms nonzonal nonadiabatic fluctuations (b(tilde sign)) relative to adiabatic ones (ã). The role of the vorticity nonlinearity in transferring energy between adiabatic and nonadiabatic fluctuations aids intuitive understanding of self-sustained turbulence in the HWEs. When the normalized parallel resistivity is weak, b(tilde sign) becomes effectively slaved, allowing the reduction to an approximate one-field model that remains valid for strong turbulence. In addition to guiding physical intuition, the one-field reduction should greatly ease further analytical manipulations. Direct numerical simulation of the 2D HWEs confirms the convergence of the asymptotic formula for b(tilde sign)

  5. Zero-Point Energy Constraint for Unimolecular Dissociation Reactions. Giving Trajectories Multiple Chances To Dissociate Correctly.

    Science.gov (United States)

    Paul, Amit K; Hase, William L

    2016-01-28

    A zero-point energy (ZPE) constraint model is proposed for classical trajectory simulations of unimolecular decomposition and applied to CH4* → H + CH3 decomposition. With this model trajectories are not allowed to dissociate unless they have ZPE in the CH3 product. If not, they are returned to the CH4* region of phase space and, if necessary, given additional opportunities to dissociate with ZPE. The lifetime for dissociation of an individual trajectory is the time it takes to dissociate with ZPE in CH3, including multiple possible returns to CH4*. With this ZPE constraint the dissociation of CH4* is exponential in time as expected for intrinsic RRKM dynamics and the resulting rate constant is in good agreement with the harmonic quantum value of RRKM theory. In contrast, a model that discards trajectories without ZPE in the reaction products gives a CH4* → H + CH3 rate constant that agrees with the classical and not quantum RRKM value. The rate constant for the purely classical simulation indicates that anharmonicity may be important and the rate constant from the ZPE constrained classical trajectory simulation may not represent the complete anharmonicity of the RRKM quantum dynamics. The ZPE constraint model proposed here is compared with previous models for restricting ZPE flow in intramolecular dynamics, and connecting product and reactant/product quantum energy levels in chemical dynamics simulations.

  6. Direction-dependent force-induced dissociation dynamics of an entropic-driven lock-and-key assembly.

    Science.gov (United States)

    Chen, Yen-Fu; Chen, Hsuan-Yi; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2017-09-01

    The unbinding dynamics of a nanosized sphere-and-cavity assembly under the pulling of constant force and constant loading rate is explored by dissipative particle dynamics simulations. The formation of this matched lock-and-key pair in a polymer solution is driven by the depletion attraction. The two-dimensional free energy landscape U(x,z) associated with this assembly is constructed. Our results indicate that the unbinding pathway along the orientation of the assembly is unfavorable due to the relatively high energy barrier compared to that along the tortuous minimum path whose energy barrier is not high. It is also found that the dissociation rate depends on the direction of the external force (θ) with respect to the assembly orientation. The presence of the force component perpendicular to the assembly orientation can reduce the bond lifetime significantly by driving the key particle to approach the minimum path. Moreover, the dissociation dynamics can be facilitated even by a pushing force compared to the spontaneous dissociation (without forces). To elucidate the effective pathway under pulling, the escaping position is analyzed and its mean direction with respect to the assembly orientation rises generally with increasing θ, revealing that the presence of the force component along the minimum pathway is helpful. The importance of the direction of the external pulling has been demonstrated in our simple system. Therefore, this effect should be considered in more complicated unbinding experiments.

  7. X-ray Pump–Probe Investigation of Charge and Dissociation Dynamics in Methyl Iodine Molecule

    Directory of Open Access Journals (Sweden)

    Li Fang

    2017-05-01

    Full Text Available Molecular dynamics is of fundamental interest in natural science research. The capability of investigating molecular dynamics is one of the various motivations for ultrafast optics. We present our investigation of photoionization and nuclear dynamics in methyl iodine (CH3I molecule with an X-ray pump X-ray probe scheme. The pump–probe experiment was realized with a two-mirror X-ray split and delay apparatus. Time-of-flight mass spectra at various pump–probe delay times were recorded to obtain the time profile for the creation of high charge states via sequential ionization and for molecular dissociation. We observed high charge states of atomic iodine up to 29+, and visualized the evolution of creating these high atomic ion charge states, including their population suppression and enhancement as the arrival time of the second X-ray pulse was varied. We also show the evolution of the kinetics of the high charge states upon the timing of their creation during the ionization-dissociation coupled dynamics. We demonstrate the implementation of X-ray pump–probe methodology for investigating X-ray induced molecular dynamics with femtosecond temporal resolution. The results indicate the footprints of ionization that lead to high charge states, probing the long-range potential curves of the high charge states.

  8. D2 dissociative adsorption on and associative desorption from Si(100): Dynamic consequences of an ab initio potential energy surface

    DEFF Research Database (Denmark)

    Luntz, A. C.; Kratzer, Peter

    1996-01-01

    favors the symmetric one. Under the conditions of many experiments, either could dominate. The calculations show quite weak dynamic coupling to the Si lattice for both paths, i.e., weak surface temperature dependences to dissociation and small energy loss to the lattice upon desorption......Dynamical calculations are reported for D-2 dissociative chemisorption on and associative desorption from a Si(100) surface. These calculations use the dynamically relevant effective potential which is based on an ab initio potential energy surface for the ''pre-paired'' species. Three coordinates...

  9. Quantum dynamics in nanoscale magnets in dissipative environments

    NARCIS (Netherlands)

    Miyashita, S; Saito, K; Kobayashi, H.; de Raedt, H.A.

    2000-01-01

    In discrete energy structure of nanoscale magnets, nonadiabatic transitions at avoided level crossings lead to fundamental processes of dynamics of magnetizations. The thermal environment causes dissipative effects on these processes. In this paper we review the features of the nonadiabatic

  10. Molecular dynamics study of CO2 hydrate dissociation: Fluctuation-dissipation and non-equilibrium analysis.

    Science.gov (United States)

    English, Niall J; Clarke, Elaine T

    2013-09-07

    Equilibrium and non-equilibrium molecular dynamics (MD) simulations have been performed to investigate thermal-driven break-up of planar CO2 hydrate interfaces in liquid water at 300-320 K. Different guest compositions, at 85%, 95%, and 100% of maximum theoretical occupation, led to statistically-significant differences in the observed initial dissociation rates. The melting temperatures of each interface were estimated, and dissociation rates were observed to be strongly dependent on temperature, with higher dissociation rates at larger over-temperatures vis-à-vis melting. A simple coupled mass and heat transfer model developed previously was applied to fit the observed dissociation profiles, and this helps to identify clearly two distinct régimes of break-up; a second well-defined region is essentially independent of composition and temperature, in which the remaining nanoscale, de facto two-dimensional system's lattice framework is intrinsically unstable. From equilibrium MD of the two-phase systems at their melting point, the relaxation times of the auto-correlation functions of fluctuations in number of enclathrated guest molecules were used as a basis for comparison of the variation in the underlying, non-equilibrium, thermal-driven dissociation rates via Onsager's hypothesis, and statistically significant differences were found, confirming the value of a fluctuation-dissipation approach in this case.

  11. Nonadiabatic three-neutrino oscillations in matter

    International Nuclear Information System (INIS)

    DOlivo, J.C.; Oteo, J.A.

    1996-01-01

    Oscillations of three neutrinos in matter are analyzed by using the Magnus expansion for the time-evolution operator. We derive a simple expression for the electron-neutrino survival probability which is applied to the examination of the effect of a third neutrino on the nonadiabatic flavor transformations. copyright 1996 The American Physical Society

  12. Theoretical study of ultraviolet induced photodissociation dynamics of sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Tatsuhiro; Ohta, Ayumi; Suzuki, Tomoya; Ikeda, Kumiko [Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-Cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Danielache, Sebastian O. [Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-Cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Earth-Life Science Institute (ELSI), Tokyo Institute of Technology (Japan); Department of Environmental Science and Techonology, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yoohama 226-8502 (Japan); Nanbu, Shinkoh, E-mail: shinkoh.nanbu@sophia.ac.jp [Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-Cho, Chiyoda-ku, Tokyo 102-8554 (Japan)

    2015-05-01

    Highlights: • Photodissociation dynamics of H{sub 2}SO{sub 4} at low-lying electronically excited states were investigated. • Photochemical processes were simulated by on-the-fly ab initio MD. • Sulfuric acid after the excitation to the S{sub 1} state dissociated to HSO{sub 4}(1{sup 2}A″) + H({sup 2}S). • Sulfuric acid after the excitation to the S{sub 2} state dissociated to HSO{sub 4}(2{sup 2}A″) + H({sup 2}S). • The energy region of the UV spectra where NMD fractionation may occur is predicted. - Abstract: Photodissociation dynamics of sulfuric acid after excitation to the first and second excited states (S{sub 1} and S{sub 2}) were studied by an on-the-fly ab initio molecular dynamics simulations based on the Zhu–Nakamura version of the trajectory surface hopping (ZN-TSH). Forces acting on the nuclear motion were computed on-the-fly by CASSCF method with Dunning’s augmented cc-pVDZ basis set. It was newly found that the parent molecule dissociated into two reaction-channels (i) HSO{sub 4}(1{sup 2}A″) + H({sup 2}S) by S{sub 1}-excitation, and (ii) HSO{sub 4}(2{sup 2}A″) + H({sup 2}S) by S{sub 2}-excitation. The direct dissociation dynamics yield products different from the SO{sub 2} + 2OH fragments often presented in the literature. Both channels result in the same product and differs only in the electronic state of the HSO{sub 4} fragment{sub .} The trajectories running on S{sub 2} do not hop with S{sub 0} and a nonadiabatic transition happens at the S{sub 2}–S{sub 1} conical intersection located at a longer OH bond-length than the S{sub 1}–S{sub 0} intersection producing an electronic excited state (2{sup 2}A″) of HSO{sub 4} product.

  13. Non-adiabatic molecular dynamics investigation of photoionization state formation and lifetime in Mn²⁺-doped ZnO quantum dots.

    Science.gov (United States)

    Fischer, Sean A; Lingerfelt, David B; May, Joseph W; Li, Xiaosong

    2014-09-07

    The unique electronic structure of Mn(2+)-doped ZnO quantum dots gives rise to photoionization states that can be used to manipulate the magnetic state of the material and to generate zero-reabsorption luminescence. Fast formation and long non-radiative decay of this photoionization state is a necessary requirement for these important applications. In this work, surface hopping based non-adiabatic molecular dynamics are used to demonstrate the fast formation of a metal-to-ligand charge transfer state in a Mn(2+)-doped ZnO quantum dot. The formation occurs on an ultrafast timescale and is aided by the large density of states and significant mixing of the dopant Mn(2+) 3dt2 levels with the valence-band levels of the ZnO lattice. The non-radiative lifetime of the photoionization states is also investigated.

  14. Dynamics of dissociative adsorption of hydrogen on Ni(100)

    International Nuclear Information System (INIS)

    Hamza, A.V.; Madix, R.J.

    1985-01-01

    Nearly monoenergetic beams of hydrogen and deuterium were used to determine dissociative sticking probabilities for H 2 and D 2 on Ni(100) at various energies. Variation of the surface temperature between 90 and 300 K had no effect on the dissociative sticking probability of H 2 at 3.6 and 5.8 kJ/mol incident beam energy, indicating a direct mechanism of dissociation. A four fold increase in the initial dissociative sticking probability for H 2 from 0.2 to 0.8 was observed by increasing the translational kinetic energy from 0.7 to 7.0 kJ/mol. The initial dissociative sticking probability for D 2 was slightly lower, increasing from 0.15 to 0.75 with increasing translational kinetic energy from 1.3 to 10.5 kJ/mol. The form of the increase with kinetic energy was explained by tunnelling through a low activation barrier, accounting as well for the high dissociation probability at low kinetic energies. The dissociative sticking probability decreased with hydrogen or deuterium adatom coverage at all energies. The decline in sticking probability with hydrogen coverage was fit to a s(theta) = s 0 (1 - a theta)/sup n/ functional form. From this relationship it was deduced that hydrogen adatoms block only single sites and that four vacant sites are needed for dissociation. The dissociative sticking probability for H 2 declined precipitously from 0.77 to 0.16 with oxygen adatom coverage from 0 to 5% of a monolayer at a translational energy of 9.6 kJ.mol. 36 references, 8 figures

  15. Multiphoton dissociation of polyatomic molecules

    International Nuclear Information System (INIS)

    Schulz, P.A.

    1979-10-01

    The dynamics of infrared multiphoton excitation and dissociation of SF 6 was investigated under collision free conditions by a crossed laser-molecular beam method. In order to understand the excitation mechanism and to elucidate the requirements of laser intensity and energy fluence, a series of experiments were carried out to measure the dissociation yield dependences on energy fluence, vibrational temperature of SF 6 , the pulse duration of the CO 2 laser and the frequency in both one and two laser experiments. Translational energy distributions of the SF 5 dissociation product measured by time of flight and angular distributions and the dissociation lifetime of excited SF 6 as inferred from the observation of secondary dissociation of SF 5 into SF 4 and F during the laser pulse suggest that the dynamics of dissociation of excited molecules is dominated by complete energy randomization and rapid intramolecular energy transfer on a nanosecond timescale, and can be adequately described by RRKM theory. An improved phenomenological model including the initial intensity dependent excitation, a rate equation describing the absorption and stimulated emission of single photons, and the unimolecular dissociation of excited molecules is constructed based on available experimental results. The model shows that the energy fluence of the laser determines the excitation of molecules in the quasi-continuum and the excess energy with which molecules dissociate after the laser pulse. The role played by the laser intensity in multiphoton dissociation is more significant than just that of overcoming the intensity dependent absorption in the lowest levels. 63 references

  16. Dissociation dynamics of CH3I in electric spark induced breakdown revealed by time-resolved laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Wang, Yang; Liu, Wei-long; Song, Yun-fei; Duo, Li-ping; Liu, Yu-qiang; Yang, Yan-qiang

    2015-01-01

    Highlights: • Emission of electric spark dissociation of CH 3 I is similar to its fs LIBS. • We use fs laser induced breakdown as a simulation for electric spark dissociation. • The I 2 molecule formation is directly observed in the time-resolved LIBS. • Bimolecular collision of I ∗ and CH 3 I is responsible for the formation of I 2 . - Abstract: The electric discharge spark dissociation of gas CH 3 I is found to be similar to its femtosecond laser photodissociation. The almost identical spectra of the two processes show that their initial ionization conditions are very similar. The initial ionization followed by molecular fragmentation is proposed as the dissociation mechanism, in which the characteristic emissions of I + , CH 3 , CH 2 , CH, H, and I 2 are identified as the dissociation products. The emission band of 505 nm I 2 is clearly observed in the time-resolved laser induced breakdown spectroscopy (LIBS). The dynamic curve indicates that I 2 ∗ molecules are formed after the delay time of ∼4.7 ns. The formation of I 2 ∗ molecule results from the bimolecular collision of the highly excited iodine atom I ∗ ( 4 P) and CH 3 I molecule. This dynamical information can help understand the process of electric discharge spark dissociation of CH 3 I

  17. Implementation of surface hopping molecular dynamics using semiempirical methods

    International Nuclear Information System (INIS)

    Fabiano, E.; Keal, T.W.; Thiel, W.

    2008-01-01

    A molecular dynamics driver and surface hopping algorithm for nonadiabatic dynamics has been implemented in a development version of the MNDO semiempirical electronic structure package. The required energies, gradients and nonadiabatic couplings are efficiently evaluated on the fly using semiempirical configuration interaction methods. The choice of algorithms for the time evolution of the nuclear motion and quantum amplitudes is discussed, and different schemes for the computation of nonadiabatic couplings are analysed. The importance of molecular orbital tracking and electronic state following is underlined in the context of configuration interaction calculations. The method is applied to three case studies (ethylene, methaniminium ion, and methanimine) using the orthogonalization corrected OM2 Hamiltonian. In all three cases decay times and dynamics paths similar to high-level ab initio results are obtained

  18. Dissociation mechanisms and dynamics of doubly charged CD3CN observed by PEPIPICO spectroscopy

    International Nuclear Information System (INIS)

    Harada, C.; Tada, S.; Yamamoto, K.; Senba, Y.; Yoshida, H.; Hiraya, A.; Wada, S.; Tanaka, K.; Tabayashi, K.

    2006-01-01

    Dissociation of free acetonitrile-d 3 molecule, CD 3 CN induced by core level excitation was studied near the nitrogen K-edge by time-of-flight fragment mass spectroscopy. A variety of atomic and molecular fragment cations such as D + , CD n + , C 2 D n + , and CD n CN + were detected using the effusive CD 3 CN beam. Photoelectron-photoion-photoion coincidence technique was applied to analyse the dissociation mechanisms and dynamics of doubly charged CD 3 CN 2+ following the N(1s-π * ) excitation. The charge separation mechanisms of core-excited CD 3 CN were discussed in connection with Auger final state distributions

  19. Optimization of mixed quantum-classical dynamics: Time-derivative coupling terms and selected couplings

    International Nuclear Information System (INIS)

    Pittner, Jiri; Lischka, Hans; Barbatti, Mario

    2009-01-01

    The usage of time-derivative non-adiabatic coupling terms and partially coupled time-dependent equations are investigated to accelerate non-adiabatic dynamics simulations at multireference configuration interaction (MRCI) level. The quality of the results and computational costs are compared against non-adiabatic benchmark dynamics calculations using non-adiabatic coupling vectors. In the comparison between the time-derivative couplings and coupling vectors, deviations in the adiabatic population of individual trajectories were observed in regions of rapid variation of the coupling terms. They, however, affected the average adiabatic population to only about 5%. For small multiconfiguration spaces, dynamics with time-derivative couplings are significantly faster than those with coupling vectors. This relation inverts for larger configuration spaces. The use of the partially coupled equations approach speeds up the simulations significantly while keeping the deviations in the population below few percent. Imidazole and the methaniminium cation are used as test examples

  20. Nonadiabatic dynamics of electron transfer in solution: Explicit and implicit solvent treatments that include multiple relaxation time scales

    International Nuclear Information System (INIS)

    Schwerdtfeger, Christine A.; Soudackov, Alexander V.; Hammes-Schiffer, Sharon

    2014-01-01

    The development of efficient theoretical methods for describing electron transfer (ET) reactions in condensed phases is important for a variety of chemical and biological applications. Previously, dynamical dielectric continuum theory was used to derive Langevin equations for a single collective solvent coordinate describing ET in a polar solvent. In this theory, the parameters are directly related to the physical properties of the system and can be determined from experimental data or explicit molecular dynamics simulations. Herein, we combine these Langevin equations with surface hopping nonadiabatic dynamics methods to calculate the rate constants for thermal ET reactions in polar solvents for a wide range of electronic couplings and reaction free energies. Comparison of explicit and implicit solvent calculations illustrates that the mapping from explicit to implicit solvent models is valid even for solvents exhibiting complex relaxation behavior with multiple relaxation time scales and a short-time inertial response. The rate constants calculated for implicit solvent models with a single solvent relaxation time scale corresponding to water, acetonitrile, and methanol agree well with analytical theories in the Golden rule and solvent-controlled regimes, as well as in the intermediate regime. The implicit solvent models with two relaxation time scales are in qualitative agreement with the analytical theories but quantitatively overestimate the rate constants compared to these theories. Analysis of these simulations elucidates the importance of multiple relaxation time scales and the inertial component of the solvent response, as well as potential shortcomings of the analytical theories based on single time scale solvent relaxation models. This implicit solvent approach will enable the simulation of a wide range of ET reactions via the stochastic dynamics of a single collective solvent coordinate with parameters that are relevant to experimentally accessible

  1. Non-adiabatic effect on Laughlin's argument of the quantum Hall effect

    International Nuclear Information System (INIS)

    Maruyama, I; Hatsugai, Y

    2009-01-01

    We have numerically studied a non-adiabatic charge transport in the quantum Hall system pumped by a magnetic flux, as one of the simplest theoretical realizations of non-adiabatic Thouless pumping. In the adiabatic limit, a pumped charge is quantized, known as Laughlin's argument in a cylindrical lattice. In a uniform electric field, we obtained a formula connecting quantized pumping in the adiabatic limit and no-pumping in the sudden limit. The intermediate region between the two limits is determined by the Landau gap. A randomness or impurity effect is also discussed.

  2. Quantum theory of nonadiabatic heavy-particle transfer processes in polar media

    International Nuclear Information System (INIS)

    Kuznetsov, A.M.

    1986-01-01

    For the probability of nonadiabatic transfer of heavy particles, a calculating procedure is proposed which in the case of certain processes allows the interaction between motion of the particle undergoing transfer and motion along other degrees of freedom to be exactly accounted for. In the case of symmetric systems, explicit expressions are obtained for the free energy of activation of the transition and for the tunneling factor which allow for nonadiabaticity of motion of the particle undergoing transfer, both in the region beneath the barrier and in the region that is classically accessible

  3. Nonadiabatic particle motion in magnetic mirror traps

    International Nuclear Information System (INIS)

    Irie, H.; Otsuka, S.; Varma, R.K.; Watanabe, T.; Nishikawa, Kyoji.

    1982-01-01

    By numerical integration of the equation of single particle motion, the basic features of the actual nonadiabatic escape of particles are studied. The results are compared with the predictions of two existing theoretical models: ''diffusion'' model derived by B. V. Chirikov and ''tunneling'' model introduced by R. K. Varma. (author)

  4. PREFACE: Sixth International Conference on Dissociative Recombination: Theory, Experiments and Applications

    Science.gov (United States)

    Wolf, Andreas; Lammich, Lutz; Schmelcher, Peter

    2005-01-01

    Dissociative recombination between electrons and molecular ions is an elementary reaction in electron-induced chemistry attracting strong attention across discipline boundaries, from fundamental questions of intramolecular dynamics to astrophysics, plasma science, as well as atmospheric and planetary physics. The process is explored on the level of atomic quantum dynamics both experimentally and theoretically, employing cold collisions at temperatures down to 10 Kelvin involving small molecules or also very large systems ranging up to biomolecules. Dissociative recombination (DR) and related processes, such as dissociative excitation, collisional cooling of vibrations and rotations, photodissociation via high-lying electronic states, resonant electron attachment, and electron-induced processes in large molecules and clusters, are studied by a variety of experimental methods, including stored and trapped molecular ions, plasma techniques such as stationary and flowing afterglow, and laser spectroscopic diagnostic of molecular excitations. The Sixth International Conference on Dissociative Recombination: Theory, Experiments and Applications (DR2004) was organized by the Research Group on Atomic and Molecular Physics with Stored Ions at the Max-Planck Institute for Nuclear Physics in Heidelberg, Germany, and held near Heidelberg in the town of Mosbach in July 2004. It was attended by about 90 scientists working in atomic and molecular physics, astrophysics, plasma- and biophysics. International Conferences on Dissociative Recombination and related processes were held before at Lake Louise, Alberta, Canada (1988), Saint Jacut, Brittany, France (1992), Ein Gedi, Israel (1995), Nässlingen, Stockholm Archipelago, Sweden (1999), and last within a symposium at the American Chemical Society meeting in Chicago, USA (2001). The presentations of this conference document a strong development of theoretical ideas towards the understanding of DR in particular in polyatomic

  5. Three cases of dissociative identity disorder and co-occurring borderline personality disorder treated with dynamic deconstructive psychotherapy.

    Science.gov (United States)

    Chlebowski, Susan M; Gregory, Robert J

    2012-01-01

    Dissociative Identity Disorder (DID) is an under-researched entity and there are no clinical trials employing manual-based therapies and validated outcome measures. There is evidence that borderline personality disorder (BPD) commonly co-occurs with DID and can worsen its course. The authors report three cases of DID with co-occurring BPD that we successfully treated with a manual-based treatment, Dynamic Deconstructive Psychotherapy (DDP). Each of the three clients achieved a 34% to 79% reduction in their Dissociative Experiences Scale scores within 12 months of initiating therapy. Dynamic Deconstructive Psychotherapy was developed for treatment refractory BPD and differs in some respects from expert consensus treatment of DID. It may be a promising modality for DID complicated by co-occurring BPD.

  6. Threshold collision-induced dissociation of diatomic molecules: a case study of the energetics and dynamics of O2- collisions with Ar and Xe.

    Science.gov (United States)

    Ahu Akin, F; Ree, Jongbaik; Ervin, Kent M; Kyu Shin, Hyung

    2005-08-08

    The energetics and dynamics of collision-induced dissociation of O2- with Ar and Xe targets are studied experimentally using guided ion-beam tandem mass spectrometry. The cross sections and the collision dynamics are modeled theoretically by classical trajectory calculations. Experimental apparent threshold energies are 2.1 and 1.1 eV in excess of the thermochemical O2- bond dissociation energy for argon and xenon, respectively. Classical trajectory calculations confirm the observed threshold behavior and the dependence of cross sections on the relative kinetic energy. Representative trajectories reveal that the bond dissociation takes place on a short time scale of about 50 fs in strong direct collisions. Collision-induced dissociation is found to be remarkably restricted to the perpendicular approach of ArXe to the molecular axis of O2-, while collinear collisions do not result in dissociation. The higher collisional energy-transfer efficiency of xenon compared with argon is attributed to both mass and polarizability effects.

  7. Threshold collision-induced dissociation of diatomic molecules: A case study of the energetics and dynamics of O2- collisions with Ar and Xe

    International Nuclear Information System (INIS)

    Ahu Akin, F.; Ree, Jongbaik; Ervin, Kent M.; Hyung, Kyu Shin

    2005-01-01

    The energetics and dynamics of collision-induced dissociation of O 2 - with Ar and Xe targets are studied experimentally using guided ion-beam tandem mass spectrometry. The cross sections and the collision dynamics are modeled theoretically by classical trajectory calculations. Experimental apparent threshold energies are 2.1 and 1.1 eV in excess of the thermochemical O 2 - bond dissociation energy for argon and xenon, respectively. Classical trajectory calculations confirm the observed threshold behavior and the dependence of cross sections on the relative kinetic energy. Representative trajectories reveal that the bond dissociation takes place on a short time scale of about 50 fs in strong direct collisions. Collision-induced dissociation is found to be remarkably restricted to the perpendicular approach of Ar/Xe to the molecular axis of O 2 - , while collinear collisions do not result in dissociation. The higher collisional energy-transfer efficiency of xenon compared with argon is attributed to both mass and polarizability effects

  8. Higher-order dynamical effects in Coulomb dissociation

    International Nuclear Information System (INIS)

    Esbensen, H.

    1994-06-01

    We study the effect of higher-order processes in Coulomb dissociation of 11 Li by numerically solving the three-dimensional time-dependent Schroedinger equation for the relative motion of a di-neutron and the 9 Li core. Comparisons are made to first-order perturbation theory and to measurements. The calculated Coulomb reacceleration effects improve the agreement with experiment, but some discrepancy remains. The effects are much smaller in the dissociation of 11 Be, and they decrease with increasing beam energy. (orig.)

  9. Mapping the dissociative ionization dynamics of molecular nitrogen with attosecond resolution

    International Nuclear Information System (INIS)

    Klinker, M; González-Vázquez, J; Martin, F; Trabattoni, A; Sansone, G; Nisoli, M; Liu, C; Linguerri, R; Hochlaf, M; Klei, J; Vrakking, M J J; Calegari, F

    2015-01-01

    We wish to understand the processes underlying the ionization dynamics of N 2 as experimentally induced and studied by recording the kinetic energy release (KER) in a XUV-pump/IR-probe setup. To this end a theoretical model was developed describing the ionization process using Dyson Orbitals and, subsequently, the dissociation process using a large set of diabatic potential energy surfaces (PES) on which to propagate. From said set of PES, a small subset is extracted allowing for the identification of one and two photon processes chiefly responsible for the experimentally observed features. (paper)

  10. Full Quantum Dynamics Simulation of a Realistic Molecular System Using the Adaptive Time-Dependent Density Matrix Renormalization Group Method.

    Science.gov (United States)

    Yao, Yao; Sun, Ke-Wei; Luo, Zhen; Ma, Haibo

    2018-01-18

    The accurate theoretical interpretation of ultrafast time-resolved spectroscopy experiments relies on full quantum dynamics simulations for the investigated system, which is nevertheless computationally prohibitive for realistic molecular systems with a large number of electronic and/or vibrational degrees of freedom. In this work, we propose a unitary transformation approach for realistic vibronic Hamiltonians, which can be coped with using the adaptive time-dependent density matrix renormalization group (t-DMRG) method to efficiently evolve the nonadiabatic dynamics of a large molecular system. We demonstrate the accuracy and efficiency of this approach with an example of simulating the exciton dissociation process within an oligothiophene/fullerene heterojunction, indicating that t-DMRG can be a promising method for full quantum dynamics simulation in large chemical systems. Moreover, it is also shown that the proper vibronic features in the ultrafast electronic process can be obtained by simulating the two-dimensional (2D) electronic spectrum by virtue of the high computational efficiency of the t-DMRG method.

  11. Thermodynamic analysis of a novel exhaust heat-driven non-adiabatic ejection-absorption refrigeration cycle using R290/oil mixture

    International Nuclear Information System (INIS)

    Li, Keqiao; Cai, Dehua; Liu, Yue; Jiang, Jingkai; Sun, Wei; He, Guogeng

    2017-01-01

    Graphical abstract: A novel air-cooled non-adiabatic ejection-absorption refrigeration cycle using R290/refrigeration oil has been thermodynamically analyzed. Influences of the ejector and the non-adiabatic absorber applications on the system performance and other system operation parameters have been investigated. The simulation results will be of great help to the miniaturization and practical application of the air-cooled absorption refrigeration system. - Highlights: • A novel air-cooled non-adiabatic ejection-absorption refrigeration cycle is proposed. • Influences of the ejector and the air-cooled non-adiabatic absorber applications on the system performance are investigated. • Variations of system performance and other system operation parameters are investigated. • R290/refrigeration oil mixture used as working pairs is analyzed. - Abstract: This paper thermodynamically analyzes a novel air-cooled non-adiabatic ejection-absorption refrigeration cycle with R290/oil mixture driven by exhaust heat. An ejector located at the upstream of the non-adiabatic absorber is employed to improve the cycle performance. Variations of COP, circulation ratio and component heat load of the system as a function of generating temperature, pressure ratio, absorption temperature, condensing temperature and evaporating temperature have been investigated in this work. The simulation results show that, compared with the conventional absorption refrigeration cycle, this non-adiabatic ejection-absorption refrigeration cycle has higher absorption efficiency, better performance, wider working condition range and lower total heat load and its COP can reach as high as 0.5297. The implementation of the ejector and the non-adiabatic absorber helps to realize the miniaturization and wider application of the absorption refrigeration system. In addition, R290/oil mixture is a kind of highly potential working pairs for absorption refrigeration.

  12. Dissociation of acetaldehyde in intense laser field: Coulomb explosion or field-assisted dissociation?

    Science.gov (United States)

    Elshakre, Mohamed E.; Gao, Lirong; Tang, Xiaoping; Wang, Sufan; Shu, Yafei; Kong, Fanao

    2003-09-01

    Dissociation of acetaldehyde in moderate strong laser field of 1013-1014W/cm2 was investigated. Singly charged parent ion CH3CHO+ and fragmental ions CH3+, CHO+, C2H4+, O+, CH2CHO+, and H+ were produced by 800 nm laser of 100 fs pulse duration and recorded by time-of-flight mass spectrometer. The CH3+ fragment further dissociated to CH2+, CH+, and C+ ions at higher intensity. Ab initio calculated results show that the singly-, doubly-, and triply charged parent ions are stable. So, the dissociation mechanism was not due to Coulomb explosion of multicharged ion. A field-assisted dissociation (FAD) theory, which assumes that only one bond undergoes dissociation while the rest of the molecular geometry stays unchanged, was employed to treat the dissociation dynamics. Accordingly, the dressed potential energy surfaces of the ground state for the parent and the fragment ions were calculated. Corresponding quasiclassical trajectory calculations show that the bond ruptures take place in the order of C-C, C-O, and C-H, agreeing with the observation. The observed angular dependence and charge distribution of the product ions can also be interpreted by the FAD theory.

  13. Nonadiabatic corrections to a quantum dot quantum computer

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 83; Issue 1. Nonadiabatic corrections to a quantum dot quantum computer working in adiabatic limit. M Ávila ... The time of operation of an adiabatic quantum computer must be less than the decoherence time, otherwise the computer would be nonoperative. So far, the ...

  14. The Aharonov-Anandan phase of a classical dynamical system seen mathematically as a quantum dynamical system

    OpenAIRE

    Segre, Gavriel

    2005-01-01

    It is shown that the non-adiabatic Hannay's angle of an integrable non-degenerate classical hamiltonian dynamical system may be related to the Aharonov-Anandan phase it develops when it is looked mathematically as a quantum dynamical system.

  15. Energetics and dynamics of excess electrons in simple fluids

    International Nuclear Information System (INIS)

    Space, B.

    1992-01-01

    Excess electronic dynamical and equilibrium properties are modeled in both polarizable and nonpolarizable noble gas fluids. Explicit dynamical calculations are carried out for excess electrons in fluid helium, where excess electronic eigenstates are localized. Energetics and dynamics are considered for fluids which span the entire range of polarizability present in the rare gases. Excess electronic eigenstates and eigenvalues are calculated for fluids of helium, argon and xenon. Both equilibrium and dynamical information is obtained from the calculation of these wavefunctions. A surface hopping trajectory method for studying nonadiabatic excess electronic relaxation in condensed systems is used to explore the nonadiabatic relaxation after photoexciting an equilibrated excess electron in dense fluid helium. The different types on nonadiabatic phenomena which are important in excess electronic relaxation are surveyed. The same surface hopping trajectory method is also used to study the rapid nonadiabatic relaxation after an excess electron is injected into unperturbed fluid helium. Several distinctively different relaxation processes, characterized by their relative importance at different times during the relaxation to a localized equilibrium state, are detailed. Though the dynamical properties of excess electrons under the conditions considered here have never been studied before, the behavior is remarkably similar to that observed in both experimental and theoretical studies of electron hydration dynamics, indicating that the processes described may be very general relaxation mechanisms for localization and trapping in fluids. Additionally, ground state energies of an excess electron, e 0 , are computed as a function of solvent density using model electron-atom pseudopotentials in fluid helium, argon, and xenon. The nonuniqueness of the pseudopotential description of electron-molecule interactions is demonstrated

  16. Dynamics of gas-phase transient species studied by dissociative photodetachment of molecular anions

    OpenAIRE

    Lu, Zhou

    2007-01-01

    Gas-phase transient species, such as the CH₃CO₂ and HOCO free radicals, play important roles in combustion and environment chemistry. In this thesis work, the dynamics of these two radicals were studied by dissociative photodetachment (DPD) of the negative ions, CH₃CO₂-С and HOCO⁻, respectively. The experiments were carried out with a fast-ion-beam photoelectron-photofragment coincidence (PPC) spectrometer. Mass-selected molecular anions in a fast ion beam were intercepted by a linearly polar...

  17. Stability and dissociation dynamics of N{sub 2}{sup ++} ions following core ionization studied by an Auger-electron–photoion coincidence method

    Energy Technology Data Exchange (ETDEWEB)

    Iwayama, H.; Shigemasa, E. [UVSOR Facility, Institute for Molecular Science, Nishigonaka 38, Myodaiji, Okazaki 444-8585 (Japan); SOKENDAI, Nishigonaka 38, Myodaiji, Okazaki 444-8585 (Japan); Kaneyasu, T. [SAGA Light Source, Tosu 841-0005 (Japan); Hikosaka, Y. [Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194 (Japan)

    2016-07-21

    An Auger-electron–photoion coincidence (AEPICO) method has been applied to study the stability and dissociation dynamics of dicationic states after the N K-shell photoionization of nitrogen molecules. From time-of-flight and kinetic energy analyses of the product ions, we have obtained coincident Auger spectra associated with metastable states of N{sub 2}{sup ++} ions and dissociative states leading to N{sub 2}{sup ++} → N{sup +} + N{sup +} and N{sup ++} + N. To investigate the production of dissociative states, we present two-dimensional AEPICO maps which reveal the correlations between the binding energies of the Auger final states and the ion kinetic energy release. These correlations have been used to determine the dissociation limits of individual Auger final states.

  18. Electron-phonon interactions and intrinsic nonadiabatic state of superconductors

    International Nuclear Information System (INIS)

    Banacky, Pavol

    2007-01-01

    Study of band structure of YBa 2 Cu 3 O 7 has shown that electron coupling to A g , B 2g and B 3g modes results in fluctuation of saddle point of one of the CuO plane d-pσ band in Y point of 1st BZ across Fermi level. It represents breakdown of adiabatic Born-Oppenheimer approximation and transition of the system into intrinsic nonadiabatic state, ω > E F . Results show that system is stabilized in this state at distorted nuclear geometry. Stabilization effect is mainly due to strong dependence of the electronic motion on instantaneous nuclear momenta. On the lattice scale, the intrinsic nonadiabatic state is geometrically degenerate at broken translation symmetry - system has fluxional nuclear configuration of O2, O3 atoms in CuO planes. It enables formation of mobile bipolarons that can move in the lattice without dissipation. Described effects are absent in non-superconducting YBa 2 Cu 3 O 6

  19. Electron phonon interactions and intrinsic nonadiabatic state of superconductors

    Science.gov (United States)

    Baňacký, Pavol

    2007-09-01

    Study of band structure of YBa 2Cu 3O 7 has shown that electron coupling to A g, B 2g and B 3g modes results in fluctuation of saddle point of one of the CuO plane d-pσ band in Y point of 1st BZ across Fermi level. It represents breakdown of adiabatic Born-Oppenheimer approximation and transition of the system into intrinsic nonadiabatic state, ω > EF. Results show that system is stabilized in this state at distorted nuclear geometry. Stabilization effect is mainly due to strong dependence of the electronic motion on instantaneous nuclear momenta. On the lattice scale, the intrinsic nonadiabatic state is geometrically degenerate at broken translation symmetry - system has fluxional nuclear configuration of O2, O3 atoms in CuO planes. It enables formation of mobile bipolarons that can move in the lattice without dissipation. Described effects are absent in non-superconducting YBa 2Cu 3O 6.

  20. Specific absorption rate determination of magnetic nanoparticles through hyperthermia measurements in non-adiabatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Coïsson, M. [INRIM, strada delle Cacce 91, 10135 Torino (Italy); Barrera, G. [INRIM, strada delle Cacce 91, 10135 Torino (Italy); University of Torino, Chemistry Department, via P. Giuria 7, 10125 Torino (Italy); Celegato, F.; Martino, L.; Vinai, F. [INRIM, strada delle Cacce 91, 10135 Torino (Italy); Martino, P. [Politronica srl, via Livorno 60, 10144 Torino (Italy); Ferraro, G. [Center for Space Human Robotics, Istituto Italiano di Tecnologia - IIT, corso Trento 21, 10129 Torino (Italy); Tiberto, P. [INRIM, strada delle Cacce 91, 10135 Torino (Italy)

    2016-10-01

    An experimental setup for magnetic hyperthermia operating in non-adiabatic conditions is described. A thermodynamic model that takes into account the heat exchanged by the sample with the surrounding environment is developed. A suitable calibration procedure is proposed that allows the experimental validation of the model. Specific absorption rate can then be accurately determined just from the measurement of the sample temperature at the equilibrium steady state. The setup and the measurement procedure represent a simplification with respect to other systems requiring calorimeters or crucial corrections for heat flow. Two families of magnetic nanoparticles, one superparamagnetic and one characterised by larger sizes and static hysteresis, have been characterised as a function of field intensity, and specific absorption rate and intrinsic loss power have been obtained. - Highlights: • Development and thermodynamic modelling of a hyperthermia setup operating in non-adiabatic conditions. • Calibration of the experimental setup and validation of the model. • Accurate measurement of specific absorption rate and intrinsic loss power in non-adiabatic conditions.

  1. First-principles investigation of the dissociation and coupling of methane on small copper clusters: Interplay of collision dynamics and geometric and electronic effects

    Energy Technology Data Exchange (ETDEWEB)

    Varghese, Jithin J.; Mushrif, Samir H., E-mail: shmushrif@ntu.edu.sg [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459 (Singapore)

    2015-05-14

    Small metal clusters exhibit unique size and morphology dependent catalytic activity. The search for alternate minimum energy pathways and catalysts to transform methane to more useful chemicals and carbon nanomaterials led us to investigate collision induced dissociation of methane on small Cu clusters. We report here for the first time, the free energy barriers for the collision induced activation, dissociation, and coupling of methane on small Cu clusters (Cu{sub n} where n = 2–12) using ab initio molecular dynamics and metadynamics simulations. The collision induced activation of the stretching and bending vibrations of methane significantly reduces the free energy barrier for its dissociation. Increase in the cluster size reduces the barrier for dissociation of methane due to the corresponding increase in delocalisation of electron density within the cluster, as demonstrated using the electron localisation function topology analysis. This enables higher probability of favourable alignment of the C–H stretching vibration of methane towards regions of high electron density within the cluster and makes higher number of sites available for the chemisorption of CH{sub 3} and H upon dissociation. These characteristics contribute in lowering the barrier for dissociation of methane. Distortion and reorganisation of cluster geometry due to high temperature collision dynamics disturb electron delocalisation within them and increase the barrier for dissociation. Coupling reactions of CH{sub x} (x = 1–3) species and recombination of H with CH{sub x} have free energy barriers significantly lower than complete dehydrogenation of methane to carbon. Thus, competition favours the former reactions at high hydrogen saturation on the clusters.

  2. First-principles investigation of the dissociation and coupling of methane on small copper clusters: Interplay of collision dynamics and geometric and electronic effects

    International Nuclear Information System (INIS)

    Varghese, Jithin J.; Mushrif, Samir H.

    2015-01-01

    Small metal clusters exhibit unique size and morphology dependent catalytic activity. The search for alternate minimum energy pathways and catalysts to transform methane to more useful chemicals and carbon nanomaterials led us to investigate collision induced dissociation of methane on small Cu clusters. We report here for the first time, the free energy barriers for the collision induced activation, dissociation, and coupling of methane on small Cu clusters (Cu n where n = 2–12) using ab initio molecular dynamics and metadynamics simulations. The collision induced activation of the stretching and bending vibrations of methane significantly reduces the free energy barrier for its dissociation. Increase in the cluster size reduces the barrier for dissociation of methane due to the corresponding increase in delocalisation of electron density within the cluster, as demonstrated using the electron localisation function topology analysis. This enables higher probability of favourable alignment of the C–H stretching vibration of methane towards regions of high electron density within the cluster and makes higher number of sites available for the chemisorption of CH 3 and H upon dissociation. These characteristics contribute in lowering the barrier for dissociation of methane. Distortion and reorganisation of cluster geometry due to high temperature collision dynamics disturb electron delocalisation within them and increase the barrier for dissociation. Coupling reactions of CH x (x = 1–3) species and recombination of H with CH x have free energy barriers significantly lower than complete dehydrogenation of methane to carbon. Thus, competition favours the former reactions at high hydrogen saturation on the clusters

  3. Nonadiabatic geometrical quantum gates in semiconductor quantum dots

    International Nuclear Information System (INIS)

    Solinas, Paolo; Zanghi, Nino; Zanardi, Paolo; Rossi, Fausto

    2003-01-01

    In this paper, we study the implementation of nonadiabatic geometrical quantum gates with in semiconductor quantum dots. Different quantum information enconding (manipulation) schemes exploiting excitonic degrees of freedom are discussed. By means of the Aharanov-Anandan geometrical phase, one can avoid the limitations of adiabatic schemes relying on adiabatic Berry phase; fast geometrical quantum gates can be, in principle, implemented

  4. Lifetime and kinetic energy release of metastable dications dissociation

    International Nuclear Information System (INIS)

    Alagia, M.; Candori, P.; Falcinelli, S.; Mundim, K.C.; Mundim, M.S.P.; Pirani, F.; Richter, R.; Stranges, S.; Vecchiocattivi, F.

    2012-01-01

    Graphical abstract: A statistical method is proposed for extracting dynamics information from coincidence data in double photoionization of molecules. Highlights: ► When a photon, with sufficient energy, hits a molecule, a doubly charged ion can be formed. This dication has often a large probability of dissociate in two positive singly charged ions. ► Experiments of photoelectron–photoion–photoion coincidence can provide valuable information about the dynamics of such dissociation processes. ► A statistical method is proposed for extracting such information from the coincidence data. - Abstract: A new method for the determination of dynamical features of the molecular dication dissociation processes, following the single photon double ionization, investigated by time-of-flight mass spectrometry technique has been developed. The method is based on an extension of the generalized simulated annealing statistical methodology, previously applied in other fields. Here it is described and applied, as an example, to the case of the dissociation of the CO 2 2+ dication giving CO + + O + ion fragments. The results are consistent with previous determination of the metastable lifetime of the dication, but the analysis also provides additional information about the dynamics of the reaction.

  5. Photoisomerization and photodissociation dynamics of reactive free radicals

    Energy Technology Data Exchange (ETDEWEB)

    Bise, Ryan T. [Univ. of California, Berkeley, CA (United States)

    2000-08-01

    The photofragmentation pathways of chemically reactive free radicals have been examined using the technique of fast beam photofragment translational spectroscopy. Measurements of the photodissociation cross-sections, product branching ratios, product state energy distributions, and angular distributions provide insight into the excited state potential energy surfaces and nonadiabatic processes involved in the dissociation mechanisms. Photodissociation spectroscopy and dynamics of the predissociative $\\tilde{A}$2A1 and $\\tilde{B}$2A2 states of CH3S have been investigated. At all photon energies, CH3 + S(3Pj), was the main reaction channel. The translational energy distributions reveal resolved structure corresponding to vibrational excitation of the CH3 umbrella mode and the S(3Pj) fine-structure distribution from which the nature of the coupled repulsive surfaces is inferred. Dissociation rates are deduced from the photofragment angular distributions, which depend intimately on the degree of vibrational excitation in the C-S stretch. Nitrogen combustion radicals, NCN, CNN and HNCN have also been studied. For all three radicals, the elimination of molecular nitrogen is the primary reaction channel. Excitation to linear excited triplet and singlet electronic states of the NCN radical generates resolved vibrational structure of the N2 photofragment. The relatively low fragment rotational excitation suggests dissociation via a symmetric C2V transition state. Resolved vibrational structure of the N2 photofragment is also observed in the photodissociation of the HNCN radical. The fragment vibrational and rotational distributions broaden with increased excitation energy. Simple dissociation models suggest that the HNCN radical isomerizes to a cyclic intermediate (c-HCNN) which then dissociates via a tight cyclic

  6. Double resonance spectroscopy of the D1Πu+ and B′′ B-bar 1Σu+ states near the third dissociation threshold of H2

    International Nuclear Information System (INIS)

    Ekey, R C; Cordova, A E; Duan, W; Chartrand, A M; McCormack, E F

    2013-01-01

    Double-resonance laser spectroscopy via the E,F 1 Σ g + ,v ′ =6,J ′ state was used to probe the energy region below the third dissociation limit of molecular hydrogen. Resonantly enhanced multi-photon ionization spectra were recorded by detecting ion production as a function of energy using a time-of-flight mass spectrometer. Energies and line widths for the v = 14–17 levels of the D 1 Π u + state of H 2 are reported and compared to experimental data obtained by using VUV synchrotron light excitation (Dickenson et al 2010 J. Chem. Phys. 133 144317) and fully ab initio non-adiabatic calculations of D 1 Π u + state energies and line widths (Glass-Maujean et al 2012 Phys. Rev. A 86 052507). Several high vibrational levels of the B ′′ B-bar 1 Σ u + state were also observed in this region. Term energies and rotational constants for the v = 67–69 vibrational levels are reported and compared to highly accurate ro-vibrational energy level predictions from fully ab initio non-adiabatic calculations of the first six 1 Σ u + levels of H 2 (Wolniewicz et al 2006 J. Mol. Spectrosc. 238 118). While additional observed transitions can be assigned to other states, several unassigned features in the spectra highlight the need for a fully integrated theoretical treatment of dissociation and ionization to understand the complex pattern of highly vibrationally excited states expected in this region. (paper)

  7. Molecular-dynamics study of propane-hydrate dissociation: Fluctuation-dissipation and non-equilibrium analysis.

    Science.gov (United States)

    Ghaani, Mohammad Reza; English, Niall J

    2018-03-21

    Equilibrium and non-equilibrium molecular-dynamics (MD) simulations have been performed to investigate thermal-driven break-up of planar propane-hydrate interfaces in contact with liquid water over the 260-320 K range. Two types of hydrate-surface water-lattice molecular termination were adopted, at the hydrate edge with water, for comparison: a 001-direct surface cleavage and one with completed cages. Statistically significant differences in melting temperatures and initial break-up rates were observed between both interface types. Dissociation rates were observed to be strongly dependent on temperature, with higher rates at larger over-temperatures vis-à-vis melting. A simple coupled mass and heat transfer model, developed previously, was applied to fit the observed dissociation profiles, and this helps us to identify clearly two distinct hydrate-decomposition régimes; following a highly temperature-dependent break-up phase, a second well-defined stage is essentially independent of temperature, in which the remaining nanoscale, de facto two-dimensional system's lattice framework is intrinsically unstable. Further equilibrium MD-analysis of the two-phase systems at their melting point, with consideration of the relaxation times gleaned from the auto-correlation functions of fluctuations in a number of enclathrated guest molecules, led to statistically significant differences between the two surface-termination cases; a consistent correlation emerged in both cases between the underlying, non-equilibrium, thermal-driven dissociation rates sampled directly from melting with that from an equilibrium-MD fluctuation-dissipation approach.

  8. Different Mechanism Effect between Gas-Solid and Liquid-Solid Interface on the Three-Phase Coexistence Hydrate System Dissociation in Seawater: A Molecular Dynamics Simulation Study

    Directory of Open Access Journals (Sweden)

    Zhixue Sun

    2017-12-01

    Full Text Available Almost 98% of methane hydrate is stored in the seawater environment, the study of microscopic mechanism for methane hydrate dissociation on the sea floor is of great significance to the development of hydrate production, involving a three-phase coexistence system of seawater (3.5% NaCl + hydrate + methane gas. The molecular dynamics method is used to simulate the hydrate dissociation process. The dissociation of hydrate system depends on diffusion of methane molecules from partially open cages and a layer by layer breakdown of the closed cages. The presence of liquid or gas phases adjacent to the hydrate has an effect on the rate of hydrate dissociation. At the beginning of dissociation process, hydrate layers that are in contact with liquid phase dissociated faster than layers adjacent to the gas phase. As the dissociation continues, the thickness of water film near the hydrate-liquid interface became larger than the hydrate-gas interface giving more resistance to the hydrate dissociation. Dissociation rate of hydrate layers adjacent to gas phase gradually exceeds the dissociation rate of layers adjacent to the liquid phase. The difficulty of methane diffusion in the hydrate-liquid side also brings about change in dissociation rate.

  9. Communication: Methane dissociation on Ni(111) surface: Importance of azimuth and surface impact site

    International Nuclear Information System (INIS)

    Shen, Xiangjian; Zhang, Zhaojun; Zhang, Dong H.

    2016-01-01

    Understanding the role of reactant ro-vibrational degrees of freedom (DOFs) in reaction dynamics of polyatomic molecular dissociation on metal surfaces is of great importance to explore the complex chemical reaction mechanism. Here, we present an expensive quantum dynamics study of the dissociative chemisorption of CH 4 on a rigid Ni(111) surface by developing an accurate nine-dimensional quantum dynamical model including the DOF of azimuth. Based on a highly accurate fifteen-dimensional potential energy surface built from first principles, our simulations elucidate that the dissociation probability of CH 4 has the strong dependence on azimuth and surface impact site. Some improvements are suggested to obtain the accurate dissociation probability from quantum dynamics simulations.

  10. Non-adiabatic rotational excitation of dipolar molecule under the ...

    Indian Academy of Sciences (India)

    J. Chem. Sci. Vol. 125, No. 5, September 2013, pp. 1213–1221. c Indian Academy of Sciences. ... The rotational wave packets of LiCl molecule excited non-adiabatically by half cycle pulse. (HCP) is .... pared to the intensities required for the ionization of ..... out and with delayed ultrashort HCP at different initial pulse dura-.

  11. Wavepacket theory of collisional dissociation in molecules

    International Nuclear Information System (INIS)

    Kulander, K.

    1980-01-01

    An explicit integration scheme is used to solve the time dependent Schroedinger equation for wavepackets which model collisions in the collinear H + H 2 system. A realistic LEPS-type potential energy surface is used. Collision energies considered are above the dissociation threshold and probabilities for collision induced dissociation are reported. Also quantum mechanical state-to-state transition probabilities are generated. These results are compared to extensive classical trajectory calculations performed on this same system. The time evolution of the wavepacket densities is studied to understand the dynamics of the collinear collisional dissociation process

  12. Photodissociation dynamics of H2O at 111.5 nm by a vacuum ultraviolet free electron laser

    Science.gov (United States)

    Wang, Heilong; Yu, Yong; Chang, Yao; Su, Shu; Yu, Shengrui; Li, Qinming; Tao, Kai; Ding, Hongli; Yang, Jaiyue; Wang, Guanglei; Che, Li; He, Zhigang; Chen, Zhichao; Wang, Xingan; Zhang, Weiqing; Dai, Dongxu; Wu, Guorong; Yuan, Kaijun; Yang, Xueming

    2018-03-01

    Photodissociation dynamics of H2O via the F ˜ state at 111.5 nm were investigated using the high resolution H-atom Rydberg "tagging" time-of-flight (TOF) technique, in combination with the tunable vacuum ultraviolet free electron laser at the Dalian Coherent Light Source. The product translational energy distributions and angular distributions in both parallel and perpendicular directions were derived from the recorded TOF spectra. Based on these distributions, the quantum state distributions and angular anisotropy parameters of OH (X) and OH (A) products have been determined. For the OH (A) + H channel, highly rotationally excited OH (A) products have been observed. These products are ascribed to a fast direct dissociation on the B ˜ 1A1 state surface after multi-step internal conversions from the initial excited F ˜ state to the B ˜ state. While for the OH (X) + H channel, very highly rotationally excited OH (X) products with moderate vibrational excitation are revealed and attributed to the dissociation via a nonadiabatic pathway through the well-known two conical intersections between the B ˜ -state and the X ˜ -state surfaces.

  13. Dynamics of coupled electron-nuclei-systems in laser fields

    International Nuclear Information System (INIS)

    Falge, Mirjam

    2012-01-01

    This work aimed at the theoretical analysis of high harmonic generation in molecules and the influence of coupled electron and nuclear dynamics on ultra-short pulse ionization processes. In the first part of this thesis, the isotope effect and influence of vibrational excitation on high harmonic generation were investigated for the isotope pairs H 2 O/D 2 O and H 2 /D 2 . It was shown that on the one hand high harmonic intensities strongly depend on the vibrational quantum number of the initial state of the water molecule and on the other hand the spectra of H 2 O and D 2 O exhibit a clear isotope effect for certain vibrationally excited states. Also it was shown that high harmonics of vibrationally excited states show an even more pronounced isotope effect than the ground state. The second and third part of this work treats the influence of coupled electron and nuclear dynamics on photoelectron spectra. In order to facilitate a numerically exact description of this dynamics, a simple one-dimensional model system (Shin-Metiu model) was used. It consists of only a single electronic and nuclear degree-of-freedom and allows for a switching between adiabatic and strongly non-adiabatic dynamics by its parameterization. This model served for the analysis of the dynamics of three different cases ranging from weak over intermediate to strong electron-nuclear coupling. To investigate the influence of non-adiabatic effects on photoelectron spectra, time-resolved photoelectron spectra were calculated applying two methods: a numerically exact treatment and an adiabatic approach neglecting the electron-nuclear coupling. Subsequently, the dependence of the efficiency of a non-adiabatic transition on the nuclear mass was analysed. To this end, the population dynamics and photoelectron spectra were calculated numerically exactly for a strong electron and nuclear coupling. Thereafter the asymmetry in forward and backward direction of time-resolved photoelectron spectra and the

  14. Universal imaging: Dissociative ionization of polyatomic molecules, chemical dynamics beamline 9.0.2

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M.; Chen, D.; Suits, A.G. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    A third endstation was recently added to the Chemical Dynamics beamline, designed to exploit the high flux broadband undulator light for a range of studies of reactive scattering, photochemistry and photoionization processes using time-of-flight mass spectroscopy coupled with position-sensitive detection. Two molecular beam sources are fixed at right angles, with the undulator light, or laser beams, intersecting the molecular beams at 45{degrees}. To date, beamline experiments have included a study of dissociative photoionization of a variety of molecules including N{sub 2}O and SF{sub 6}. In this mode, a single molecular beam source is used, with the tunable undulator light inducing, in SF{sub 6} for example, the process SF{sub 6} {r_arrow} SF{sub 6}{sup +} + e{sup {minus}} {r_arrow} SF{sub 5}{sup +} + F + e{sup {minus}}. The SF{sub 5}{sup +} ions are accelerated up the flight tube, mass selected and detected as a function of position on a phosphor screen viewed by a CCD camera. The position directly reveals the recoil speed (or translational energy release) and angular distribution for the dissociative ionization process. Furthermore, this measurement is obtained for all recoil speeds and angles simultaneously. Such detailed angular information has not previously been obtained for dissociative ionization processes; typically ion time-of-flight profiles are deconvoluted to yield rough insight into the angular distributions. The recorded image is actually a 2-dimensional projection of the nascent 3-dimensional velocity distribution, but established tomographic techniques enable the authors to reconstruct the 3-D distribution.

  15. Prediction of electronically nonadiabatic decomposition mechanisms of isolated gas phase nitrogen-rich energetic salt: Guanidium-triazolate

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Jayanta; Bhattacharya, Atanu, E-mail: atanub@ipc.iisc.ernet.in

    2016-01-13

    Highlights: • Decomposition mechanisms of model energetic salt, guanidium triazolate, are explored. • Decomposition pathways are electronically nonadiabatic. • CASPT2, CASMP2 and CASSCF methodologies are employed. • N{sub 2} and NH{sub 3} are predicted to be the most possible initial decomposition products. - Abstract: Electronically nonadiabatic decomposition pathways of guanidium triazolate are explored theoretically. Nonadiabatically coupled potential energy surfaces are explored at the complete active space self-consistent field (CASSCF) level of theory. For better estimation of energies complete active space second order perturbation theories (CASPT2 and CASMP2) are also employed. Density functional theory (DFT) with B3LYP functional and MP2 level of theory are used to explore subsequent ground state decomposition pathways. In comparison with all possible stable decomposition products (such as, N{sub 2}, NH{sub 3}, HNC, HCN, NH{sub 2}CN and CH{sub 3}NC), only NH{sub 3} (with NH{sub 2}CN) and N{sub 2} are predicted to be energetically most accessible initial decomposition products. Furthermore, different conical intersections between the S{sub 1} and S{sub 0} surfaces, which are computed at the CASSCF(14,10)/6-31G(d) level of theory, are found to play an essential role in the excited state deactivation process of guanidium triazolate. This is the first report on the electronically nonadiabatic decomposition mechanisms of isolated guanidium triazolate salt.

  16. Impact of Turbocharger Non-Adiabatic Operation on Engine Volumetric Efficiency and Turbo Lag

    Directory of Open Access Journals (Sweden)

    S. Shaaban

    2012-01-01

    Full Text Available Turbocharger performance significantly affects the thermodynamic properties of the working fluid at engine boundaries and hence engine performance. Heat transfer takes place under all circumstances during turbocharger operation. This heat transfer affects the power produced by the turbine, the power consumed by the compressor, and the engine volumetric efficiency. Therefore, non-adiabatic turbocharger performance can restrict the engine charging process and hence engine performance. The present research work investigates the effect of turbocharger non-adiabatic performance on the engine charging process and turbo lag. Two passenger car turbochargers are experimentally and theoretically investigated. The effect of turbine casing insulation is also explored. The present investigation shows that thermal energy is transferred to the compressor under all circumstances. At high rotational speeds, thermal energy is first transferred to the compressor and latter from the compressor to the ambient. Therefore, the compressor appears to be “adiabatic” at high rotational speeds despite the complex heat transfer processes inside the compressor. A tangible effect of turbocharger non-adiabatic performance on the charging process is identified at turbocharger part load operation. The turbine power is the most affected operating parameter, followed by the engine volumetric efficiency. Insulating the turbine is recommended for reducing the turbine size and the turbo lag.

  17. Quantum dynamics of water dissociative chemisorption on rigid Ni(111): An approximate nine-dimensional treatment

    International Nuclear Information System (INIS)

    Jiang, Bin; Song, Hongwei; Yang, Minghui; Guo, Hua

    2016-01-01

    The quantum dynamics of water dissociative chemisorption on the rigid Ni(111) surface is investigated using a recently developed nine-dimensional potential energy surface. The quantum dynamical model includes explicitly seven degrees of freedom of D 2 O at fixed surface sites, and the final results were obtained with a site-averaging model. The mode specificity in the site-specific results is reported and analyzed. Finally, the approximate sticking probabilities for various vibrationally excited states of D 2 O are obtained considering surface lattice effects and formally all nine degrees of freedom. The comparison with experiment reveals the inaccuracy of the density functional theory and suggests the need to improve the potential energy surface.

  18. A spherical electron cloud hopping model for studying product branching ratios of dissociative recombination.

    Science.gov (United States)

    Yu, Hua-Gen

    2008-05-21

    A spherical electron cloud hopping (SECH) model is proposed to study the product branching ratios of dissociative recombination (DR) of polyatomic systems. In this model, the fast electron-captured process is treated as an instantaneous hopping of a cloud of uniform spherical fractional point charges onto a target M+q ion (or molecule). The sum of point charges (-1) simulates the incident electron. The sphere radius is determined by a critical distance (Rc eM) between the incoming electron (e-) and the target, at which the potential energy of the e(-)-M+q system is equal to that of the electron-captured molecule M+q(-1) in a symmetry-allowed electronic state with the same structure as M(+q). During the hopping procedure, the excess energies of electron association reaction are dispersed in the kinetic energies of M+q(-1) atoms to conserve total energy. The kinetic energies are adjusted by linearly adding atomic momenta in the direction of driving forces induced by the scattering electron. The nuclear dynamics of the resultant M+q(-1) molecule are studied by using a direct ab initio dynamics method on the adiabatic potential energy surface of M+q(-1), or together with extra adiabatic surface(s) of M+q(-1). For the latter case, the "fewest switches" surface hopping algorithm of Tully was adapted to deal with the nonadiabaticity in trajectory propagations. The SECH model has been applied to study the DR of both CH+ and H3O+(H2O)2. The theoretical results are consistent with the experiment. It was found that water molecules play an important role in determining the product branching ratios of the molecular cluster ion.

  19. Non-adiabatic generator-coordinate calculation of H2+

    International Nuclear Information System (INIS)

    Tostes, J.G.R.; Para Univ., Belem; Toledo Piza, A.F.R. de

    1982-10-01

    A non-adiabatic calculation of the few lowest J=O states in the H 2+ molecule done within the framework of the Generator Coordinate Method is reported. Substantial accuracy is achivied with the diagonalization of matrices of very modest dimensions. The resulting wavefunctions are strongly dominated by just a few basis states. The computational scheme is set up so as to take the best advantage of good analytical approximations to existing adiabatic molecular wavefunctions. (Author) [pt

  20. Doping effect on photoabsorption and charge-separation dynamics in light-harvesting organic molecule

    Directory of Open Access Journals (Sweden)

    Satoshi Ohmura

    2016-01-01

    Full Text Available Using ab-initio theoretical methods, we demonstrate possible enhancement of photo-conversion efficiency of an organic solar cell via intentional doping in molecular graphene-fullerene heterojunction [the hexabenzocoronene (HBC-triethylene glycol (TEG–C60 molecule]. Photoabsorption analysis indicates oxygen substitution into HBC leads to an extension of the spectra up to an infrared regime. A quantum-mechanical molecular dynamics simulation incorporating nonadiabatic electronic transitions reveals that a dissociated charge state (D+ and A- in the O-doped system is more stable than the pristine case due to the presence of an effective barrier by the TEG HOMO/LUMO level. We also find that oxygen doping in HBC enhances the intermolecular carrier mobility after charge separation. On the other hand, the pristine molecule undergoes rapid recombination between donor and acceptor charges at the interface. These analyses suggest that the graphene oxidation opens a new window in the application of organic super-molecules to solar cells.

  1. Doping effect on photoabsorption and charge-separation dynamics in light-harvesting organic molecule

    Energy Technology Data Exchange (ETDEWEB)

    Ohmura, Satoshi, E-mail: s.ohmura.m4@cc.it-hiroshima.ac.jp [Research Center for Condensed Matter Physics, Department of Civil Engineering and Urban Design, Hiroshima Institute of Technology, Hiroshima 731-5193 (Japan); Tsuruta, Kenji [Department of Electrical and Electronic Engineering, Okayama University, Okayama 700-8530 (Japan); Shimojo, Fuyuki [Department of Physics, Kumamoto University, Kumamoto 860-8555 Japan (Japan); Nakano, Aiichiro [Collaboratory for Advanced Computing and Simulations, Department of Computer Science, Department of Physics & Astronomy, Department of Chemical Engineering & Materials Science, Department of Biological Sciences, University of Southern California, CA90089-024 (United States)

    2016-01-15

    Using ab-initio theoretical methods, we demonstrate possible enhancement of photo-conversion efficiency of an organic solar cell via intentional doping in molecular graphene-fullerene heterojunction [the hexabenzocoronene (HBC)-triethylene glycol (TEG)–C{sub 60} molecule]. Photoabsorption analysis indicates oxygen substitution into HBC leads to an extension of the spectra up to an infrared regime. A quantum-mechanical molecular dynamics simulation incorporating nonadiabatic electronic transitions reveals that a dissociated charge state (D{sup +} and A{sup -}) in the O-doped system is more stable than the pristine case due to the presence of an effective barrier by the TEG HOMO/LUMO level. We also find that oxygen doping in HBC enhances the intermolecular carrier mobility after charge separation. On the other hand, the pristine molecule undergoes rapid recombination between donor and acceptor charges at the interface. These analyses suggest that the graphene oxidation opens a new window in the application of organic super-molecules to solar cells.

  2. Classical analog for electronic degrees of freedom in nonadiabatic collision processes

    International Nuclear Information System (INIS)

    Meyer, H.; Miller, W.H.

    1979-01-01

    It is shown how a formally exact classical analog can be defined for a finite dimensional (in Hilbert space) quantum mechanical system. This approach is then used to obtain a classical model for the electronic degrees of freedom in a molecular collision system, and the combination of this with the usual classical description of the heavy particle (i.e., nuclear) motion provides a completely classical model for the electronic and heavy particle degrees of freedom. The resulting equations of motion are shown to be equivalent to describing the electronic degrees of freedom by the time-dependent Schroedinger equation, the time dependence arising from the classical motion of the nuclei, the trajectory of which is determined by the quantum mechanical average (i.e., Ehrenfest) force on the nuclei. Quantizing the system via classical S-matrix theory is shown to provide a dynamically consistent description of nonadiabatic collision processes; i.e., different electronic transitions have different heavy particle trajectories and, for example, the total energy of the electronic and heavy particle degrees of freedom is conserved. Application of this classical model for the electronic degrees of freedom (plus classical S-matrix theory) to the two-state model problem shows that the approach provides a good description of the electronic dynamics

  3. Generation of helical electron beams by a nonadiabatic gun

    International Nuclear Information System (INIS)

    Barroso, J.J.; Stellati, C.

    1996-01-01

    The design of a non-adiabatic gun to produce a 10A, 50kV hollow laminar electron beam for gyrotron applications is reported. The beam is extracted from the emitting ring in a direction parallel to the axial guide magnetic field and then propagates across the radial electric field in the anode gap. The electrons are thereby given a transverse velocity upon passing through the modulation anode region where an electrostatic pumping mechanism takes place, so that a considerable amount of the electron energy is converted to transverse kinetic energy. Such a beam extraction method gives rise to favourable features that are examined throughout the work. The dynamics of hollow electron beams with gyromotion propagating down a cylindrical drift tube are also analysed. Due to the action of the beam's self-space charge field, the transverse velocity spread has an oscillatory behaviour along the drift tube wherein the spatial automodulation period shortens with increasing current. Numerical simulation results indicate that even at a 10A beam current, the resulting transverse velocity spread is still less than the spread for a zero beam current. (UK)

  4. Comparison of reactivity on step and terrace sites of Pd (3 3 2) surface for the dissociative adsorption of hydrogen: A quantum chemical molecular dynamics study

    International Nuclear Information System (INIS)

    Ahmed, Farouq; Nagumo, Ryo; Miura, Ryuji; Ai, Suzuki; Tsuboi, Hideyuki; Hatakeyama, Nozomu; Endou, Akira; Takaba, Hiromitsu; Kubo, Momoji; Miyamoto, Akira

    2011-01-01

    The notion of 'active sites' is fundamental to heterogeneous catalysis. However, the exact nature of the active sites, and hence the mechanism by which they act, are still largely a matter of speculation. In this study, we have presented a systematic quantum chemical molecular dynamics (QCMD) calculations for the interaction of hydrogen on different step and terrace sites of the Pd (3 3 2) surface. Finally the dissociative adsorption of hydrogen on step and terrace as well as the influence of surface hydrogen vacancy for the dissociative adsorption of hydrogen has been investigated through QCMD. This is a state-of-the-art method for calculating the interaction of atoms and molecules with metal surfaces. It is found that fully hydrogen covered (saturated) step sites can dissociate hydrogen moderately and that a monovacancy surface is suitable for significant dissociative adsorption of hydrogen. However in terrace site of the surface we have found that dissociation of hydrogen takes place only on Pd sites where the metal atom is not bound to any pre-adsorbed hydrogen atoms. Furthermore, from the molecular dynamics and electronic structure calculations, we identify a number of consequences for the interpretation and modeling of diffusion experiments demonstrating the coverage and directional dependence of atomic hydrogen diffusion on stepped palladium surface.

  5. Systemic Case Formulation, Individualized Process Monitoring, and State Dynamics in a Case of Dissociative Identity Disorder.

    Science.gov (United States)

    Schiepek, Günter K; Stöger-Schmidinger, Barbara; Aichhorn, Wolfgang; Schöller, Helmut; Aas, Benjamin

    2016-01-01

    Objective: The aim of this case report is to demonstrate the feasibility of a systemic procedure (synergetic process management) including modeling of the idiographic psychological system and continuous high-frequency monitoring of change dynamics in a case of dissociative identity disorder. The psychotherapy was realized in a day treatment center with a female client diagnosed with borderline personality disorder (BPD) and dissociative identity disorder. Methods: A three hour long co-creative session at the beginning of the treatment period allowed for modeling the systemic network of the client's dynamics of cognitions, emotions, and behavior. The components (variables) of this idiographic system model (ISM) were used to create items for an individualized process questionnaire for the client. The questionnaire was administered daily through an internet-based monitoring tool (Synergetic Navigation System, SNS), to capture the client's individual change process continuously throughout the therapy and after-care period. The resulting time series were reflected by therapist and client in therapeutic feedback sessions. Results: For the client it was important to see how the personality states dominating her daily life were represented by her idiographic system model and how the transitions between each state could be explained and understood by the activating and inhibiting relations between the cognitive-emotional components of that system. Continuous monitoring of her cognitions, emotions, and behavior via SNS allowed for identification of important triggers, dynamic patterns, and psychological mechanisms behind seemingly erratic state fluctuations. These insights enabled a change in management of the dynamics and an intensified trauma-focused therapy. Conclusion: By making use of the systemic case formulation technique and subsequent daily online monitoring, client and therapist continuously refer to detailed visualizations of the mental and behavioral network and

  6. Systemic Case Formulation, Individualized Process Monitoring, and State Dynamics in a Case of Dissociative Identity Disorder.

    Directory of Open Access Journals (Sweden)

    Guenter Karl Schiepek

    2016-10-01

    Full Text Available Objective. The aim of this case report is to demonstrate the feasibility of a systemic procedure (synergetic process management including modeling of the idiographic psychological system and continuous high-frequency monitoring of change dynamics in a case of dissociative identity disorder. The psychotherapy was realized in a day treatment center with a female client diagnosed with borderline personality disorder (BPD and dissociative identity disorder. Methods. A three hour long co-creative session at the beginning of the treatment period allowed for modeling the systemic network of the client’s dynamics of cognitions, emotions, and behavior. The components (variables of this idiographic system model (ISM were used to create items for an individualized process questionnaire for the client. The questionnaire was administered daily through an internet-based monitoring tool (Synergetic Navigation System, SNS, to capture the client’s individual change process continuously throughout the therapy and after-care period. The resulting time series were reflected by therapist and client in therapeutic feedback sessions. Results. For the client it was important to see how the personality states dominating her daily life were represented by her idiographic system model and how the transitions between each state could be explained and understood by the activating and inhibiting relations between the cognitive-emotional components of that system. Continuous monitoring of her cognitions, emotions, and behavior via SNS allowed for identification of important triggers, dynamic patterns, and psychological mechanisms behind seemingly erratic state fluctuations. These insights enabled a change in management of the dynamics and an intensified trauma-focused therapy. Conclusion. By making use of the systemic case formulation technique and subsequent daily online monitoring, client and therapist continuously refer to detailed visualizations of the mental and

  7. SELF-HEALING NANOMATERIALS: MULTIMILLION-ATOM REACTIVE MOLECULAR DYNAMICS SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Hakamata, Tomoya [Kumamoto Univ., Kumamoto (Japan); Shimamura, Kohei [Kumamoto Univ., Kumamoto (Japan); Univ. of Southern California, Los Angeles, CA (United States); Kobe Univ., Kobe (Japan); Shimojo, Fuyuki [Kumamoto Univ., Kumamoto (Japan); Kalia, Rajiv K. [Univ. of Southern California, Los Angeles, CA (United States); Nakano, Aiichiro [Univ. of Southern California, Los Angeles, CA (United States); Vashishta, Priya [Univ. of Southern California, Los Angeles, CA (United States)

    2017-10-20

    Organometal halide perovskites are attracting great attention as promising material for solar cells because of their high power conversion efficiency. The high performance has been attributed to the existence of free charge carriers and their large diffusion lengths, but the nature of carrier transport at the atomistic level remains elusive. Here, nonadiabatic quantum molecular dynamics simulations elucidate the mechanisms underlying the excellent free-carrier transport in CH3NH3PbI3. Pb and I sublattices act as disjunct pathways for rapid and balanced transport of photoexcited electrons and holes, respectively, while minimizing efficiency-degrading charge recombination. On the other hand, CH3NH3 sublattice quickly screens out electrostatic electron-hole attraction to generate free carriers within 1 ps. Together this nano-architecture lets photoexcited electrons and holes dissociate instantaneously and travel far away to be harvested before dissipated as heat. As a result, this work provides much needed structure-property relationships and time-resolved information that potentially lead to rational design of efficient solar cells.

  8. Experimental investigation of the reverse heat transfer of R134a flow through non-adiabatic coiled capillary tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zareh, Masoud; Heidari, Mohammad Ghorbani [Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2016-07-15

    This research represents an experimental investigation of the metastable flow and re-condensation phenomenon through non-adiabatic lateral helical capillary tubes and suction tube heat exchanger. The results show that mass flux ratio has a vital role: It affects metastable flow and also reverse heat transfer phenomenon through non-adiabatic helical capillary tube. Therefore, by increasing of the mass flux ratio, the rate of heat transfer between them decreases. In contrast to the strong rate condition of heat transfer between them, reverse heat transfer or re-condensation maybe happen. Moreover, experimental results show that for R134 flow with mass flux ratio more than 57.84, metastable flow exists in non-adiabatic capillary tube with 0.9144 mm inner diameter, 30 mm coil diameter, 6.18 m length, 4 mm inner diameter of compressor suction tube.

  9. Observational tests of non-adiabatic Chaplygin gas

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, S.; Pigozzo, C., E-mail: saulo.carneiro@pq.cnpq.br, E-mail: cpigozzo@ufba.br [Instituto de Física, Universidade Federal da Bahia, Campus de Ondina, Salvador, BA 40210-340 (Brazil)

    2014-10-01

    In a previous paper [1] it was shown that any dark sector model can be mapped into a non-adiabatic fluid formed by two interacting components, one with zero pressure and the other with equation-of-state parameter ω = -1. It was also shown that the latter does not cluster and, hence, the former is identified as the observed clustering matter. This guarantees that the dark matter power spectrum does not suffer from oscillations or instabilities. It applies in particular to the generalised Chaplygin gas, which was shown to be equivalent to interacting models at both background and perturbation levels. In the present paper we test the non-adiabatic Chaplygin gas against the Hubble diagram of type Ia supernovae, the position of the first acoustic peak in the anisotropy spectrum of the cosmic microwave background and the linear power spectrum of large scale structures. We consider two different compilations of SNe Ia, namely the Constitution and SDSS samples, both calibrated with the MLCS2k2 fitter, and for the power spectrum we use the 2dFGRS catalogue. The model parameters to be adjusted are the present Hubble parameter, the present matter density and the Chaplygin gas parameter α. The joint analysis best fit gives α ≈ - 0.5, which corresponds to a constant-rate energy flux from dark energy to dark matter, with the dark energy density decaying linearly with the Hubble parameter. The ΛCDM model, equivalent to α = 0, stands outside the 3σ confidence interval.

  10. Influence of light-induced conical intersection on the photodissociation dynamics of D2(+) starting from individual vibrational levels.

    Science.gov (United States)

    Halász, Gábor J; Csehi, András; Vibók, Ágnes; Cederbaum, Lorenz S

    2014-12-26

    Previous works have shown that dressing of diatomic molecules by standing or by running laser waves gives rise to the appearance of so-called light-induced conical intersections (LICIs). Because of the strong nonadiabatic couplings, the existence of such LICIs may significantly change the dynamical properties of a molecular system. In our former paper (J. Phys. Chem. A 2013, 117, 8528), the photodissociation dynamics of the D(2)(+) molecule were studied in the LICI framework starting the initial vibrational nuclear wave packet from the superposition of all the vibrational states initially produced by ionizing D(2). The present work complements our previous investigation by letting the initial nuclear wave packets start from different individual vibrational levels of D(2)(+), in particular, above the energy of the LICI. The kinetic energy release spectra, the total dissociation probabilities, and the angular distributions of the photofragments are calculated and discussed. An interesting phenomenon has been found in the spectra of the photofragments. Applying the light-induced adiabatic picture supported by LICI, explanations are given for the unexpected structure of the spectra.

  11. The nonadiabatic deactivation paths of pyrrole

    International Nuclear Information System (INIS)

    Barbatti, Mario; Vazdar, Mario; Aquino, Adelia J. A.; Eckert-Maksic, Mirjana; Lischka, Hans

    2006-01-01

    Multireference configuration interaction (MRCI) calculations have been performed for pyrrole with the aim of providing an explanation for the experimentally observed photochemical deactivation processes. Potential energy curves and minima on the crossing seam were determined using the analytic MRCI gradient and nonadiabatic coupling features of the COLUMBUS program system. A new deactivation mechanism based on an out-of-plane ring deformation is presented. This mechanism directly couples the charge transfer 1 ππ* and ground states. It may be responsible for more than 50% of the observed photofragments of ππ*-excited pyrrole. The ring deformation mechanism should act complementary to the previously proposed NH-stretching mechanism, thus offering a more complete interpretation of the pyrrole photodynamics

  12. Are Nonadiabatic Reaction Dynamics the Key to Novel Organosilicon Molecules? The Silicon (Si(3P))-Dimethylacetylene (C4H6(X1A1g)) System as a Case Study.

    Science.gov (United States)

    Thomas, Aaron M; Dangi, Beni B; Yang, Tao; Kaiser, Ralf I; Lin, Lin; Chou, Tzu-Jung; Chang, Agnes H H

    2018-06-06

    The bimolecular gas phase reaction of ground-state silicon (Si; 3 P) with dimethylacetylene (C 4 H 6 ; X 1 A 1g ) was investigated under single collision conditions in a crossed molecular beams machine. Merged with electronic structure calculations, the data propose nonadiabatic reaction dynamics leading to the formation of singlet SiC 4 H 4 isomer(s) and molecular hydrogen (H 2 ) via indirect scattering dynamics along with intersystem crossing (ISC) from the triplet to the singlet surface. The reaction may lead to distinct energetically accessible singlet SiC 4 H 4 isomers ( 1 p8- 1 p24) in overall exoergic reaction(s) (-107 -20 +12 kJ mol -1 ). All feasible reaction products are either cyclic, carry carbene analogous silylene moieties, or carry C-Si-H or C-Si-C bonds that would require extensive isomerization from the initial collision complex(es) to the fragmenting singlet intermediate(s). The present study demonstrates the first successful crossed beams study of an exoergic reaction channel arising from bimolecular collisions of silicon, Si( 3 P), with a hydrocarbon molecule.

  13. Dynamical explanation for the experimentally observed μs lifetime for D3O

    International Nuclear Information System (INIS)

    McLoughlin, P.W.; Gellene, G.I.

    1990-01-01

    The minimum energy pathway (MEP) for H atom addition to H 2 O has been determined by ab initio calculations at the MP3 level using a large Rydberg basis set. In agreement with previous theoretical studies, a local minimum in a C 3v geometry was found lying about 18.4 kcal/mol above the energy of H 2 O + H, but separated from the products by a 3.9 kcal/mol barrier. The well depth is sufficient to contain a quasi-bound zero point level, however, tunneling lifetimes, estimated to be 10 -13 to 10 -12 s, contrast sharply with the experimental results of neutralized ion beam studies which indicate a ∼1 μs lifetime for D 3 O. Exploration of the region of the potential energy surface around the MEP, shows the pathway to preserve a symmetry plane containing the H fragment and bisecting the H 2 O fragment (i.e., C s symmetry) with the dissociation coordinate lying in the A' coordinate subspace. Vibrationally adiabatic potential curves correlating to H 2 O products with excitation in the asymmetric stretch are found to have increased dissociation barriers for increased excitation with ∼μs lifetimes occurring for v ≥ 3. The interpretation that the experimentally observed metastability of D 3 O arises from this essentially dynamical dissociation barrier makes the radical a remarkable example of a quasi-bound species, lasting ∼1 μs with 10.5 kcal/mol of internal energy in excess of the semiclassical dissociation barrier. Isotope effects on the magnitude of possible nonadiabatic kinetic and potential couplings are estimated and discussed in light of the experimental lifetime scaling D 3 16 O>D 3 18 O≥H 3 16 O

  14. Particle pitch angle diffusion due to nonadiabatic effects in the plasma sheet

    International Nuclear Information System (INIS)

    Gray, P.C.; Lee, L.C.

    1982-01-01

    In order to understand certain aspects of the plasma sheet dynamics, a numerical study of the nonadiabatic behavior of particles in a model field geometry is performed. The particle's magnetic moment as a function of time is calculated for various initial parameters, corresponding to various particle energies and degrees of field curvature. It is shown that the magnetic moment changes as the particle passes through the plasma sheet and that the magnitude of the change is related to the curvature of the field at the middle of the plasma sheet. The relation of the magnitude of the change in magnetic moment to the particle's pitch and phase angles as it passes through the sheet is numerically resolved. The nature of the change may be considered as a mechanism for pitch angle diffusion, and the diffusion coefficient is calculated. This scattering mechanism is significant for plasma sheet ions (1--10 keV) as well as energetic electrons (>100 keV)

  15. Energy distribution in dissociations of polyatomic molecules

    International Nuclear Information System (INIS)

    Koernig, S.A.

    1989-01-01

    In this thesis studies are reported of fragmentation processes in polyatomic molecules. In order to find out which dessocaciation reactions take place, how they are brought about by the internal energy of the reactant, and to investigate the structure of the dissociating 'transition state', the fragment mass and the corresponding kinetic energy release (KER) are determined by differential translational spectroscopy using a position and time sensitive two-particle coincidence detector. The results are interpreted using the statistical theory of unimolecular dissociation. It turns out that the standard assumptions of the theory, especially in calculating KER-distributions, are not realistic in all molecules considered. Dissociation is induced by the neutralization with alkali metal vapour. In ch. 2 the experimental method and the analysis of the data (dissociation pathways, branching ratios and ε-d-distributions) are introduced and exemplified by measurements of cyclohexane, which represents the upper limit in precursor and fragment mass accessible in the apparatus. In ch. 3 a study is reported of the molecules methylchloride (CH 3 Cl) and the acetylradical (CH 3 CO). In spite of their similar geometric structures, completely different dissociation mechanisms have been found. Methylchloride dissociates via a repulsive state; acetyl radicals show energy scrambling. The energy distribution from dissociating acetyl exemplifies dynamical effects in the dissociation. In ch. 4 an investigation of a number of prototype hydrocarbons is presented. The dissociation pathways of several small linear alkanes indicate that neutralization takes place to unknown repulsive potentials, of which the position and steepness are determined from the kinetic energy release. (author). 118 refs.; 40 figs.; 5 tabs

  16. Profiling the overdamped dynamics of a nonadiabatic system

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Prasun [Department of Chemistry, Bose Institute, 93/1 A P C Road, Kolkata 700009 (India); Shit, Anindita [Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103 (India); Chattopadhyay, Sudip, E-mail: sudip_chattopadhyay@rediffmail.com [Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103 (India); Banik, Suman K., E-mail: skbanik@jcbose.ac.in [Department of Chemistry, Bose Institute, 93/1 A P C Road, Kolkata 700009 (India)

    2015-09-08

    Graphical abstract: The theoretical analysis that is addressed here can be used to illustrate both a qualitative and a quantitative understanding of the dynamics of a particle in the presence of an external probe. - Highlights: • Interaction of systems with strong fields results in many interesting observations. • The relevant systems are characterized by an extremely high degree of control. • The theory that is addressed here is useful to investigate the transport process. • Effective to understand the trapping mechanism in a rapidly oscillating potential. • Useful to study the dynamics of particles in the presence of an external probe. - Abstract: Rapidly oscillating time-periodic potentials with a vanishing time average have been exploited to investigate the dynamics of an overdamped particle. Using the multiple scale perturbation theory, it has been shown that the dynamics can be adequately characterized by an explicitly time-independent effective potential. The resulting “effective equation of motion” can offer various avenues to handle the dynamics of the system driven by a high-frequency field. We study the effects of the field parameters on the mobility of the overdamped particle moving in the effective potential. The variation of the mobility with the field parameters is associated with the interplay of spatially periodic gradients, time periodic modulation and thermal noise in the overdamped region. Good agreement between the simulations and theoretical estimates validates our methodology that captures the constitutional features ruling the dynamics in the overdamped limit. The results observed here can also be extended to the quantum system.

  17. Approximations to the non-adiabatic particle response in toroidal geometry

    International Nuclear Information System (INIS)

    Schep, T.J.; Braams, B.J.

    1981-08-01

    The non-adiabatic part of the particle response to low-frequency electromagnetic modes with long parallel wavelengths is discussed. Analytic approximations to the kernels of the integrals that relate the amplitudes of the perturbed potentials to the non-adiabatic part of the perturbed density in an axisymmetric toroidal configuration are presented and the results are compared with numerical calculations. It is shown that both in the plane slab and in toroidal geometry the kernel contains a logarithmic singularity. This singularity is associated with particles with vanishing parallel velocity so that, in toroidal geometry, it is related with the behaviour of trapped particles near their turning points. In contrast to the plane slab, in toroidal geometry this logarithmic singularity is mainly real and associated with non-resonant particles. Apart from this logarithmic term, the kernel contains a complex regular part arising from resonant as well as from non-resonant particles. The analytic approximations that will be presented make the dispersion relation of drift-type modes in toroidal geometry amenable to analytic as well as to simpler numerical calculation of the growth rate and of the spatial mode structure

  18. Development of a model for dimethyl ether non-adiabatic reactors to improve methanol conversion

    Energy Technology Data Exchange (ETDEWEB)

    Nasrollahi, Fatemeh [University of Tehran, Tehran (Iran, Islamic Republic of); Bakeri, Gholamreza; Rahimnejad, Mostafa [Babol Noshirvani University of Technology, Babol (Iran, Islamic Republic of); Ismail, Ahmad Fauzi [Universiti Teknologi Malaysia, Skudai (Malaysia); Imanian, Mahdi [Mohajer Technical University, Isfahan (Iran, Islamic Republic of)

    2013-10-15

    The modeling of adiabatic and non-adiabatic reactors, using three cooling mediums in the shell side of a shell and tube reactor in cocurrent and countercurrent flow regimes has been conducted. The cooling mediums used in this research are saturated water and methanol feed gas to a reactor which is preheated in the shell side and a special type of oil. The results of adiabatic reactor modeling show good compatibility with the data received from a commercial plant. The results of non-adiabatic reactor modeling showed that more methanol conversion can be achieved in a lower length of reactor, even though in some cases the maximum temperature in the tube side of the reactor is more than the deactivation temperature of the catalyst.

  19. 1ST-ORDER NONADIABATIC COUPLING MATRIX-ELEMENTS FROM MULTICONFIGURATIONAL SELF-CONSISTENT-FIELD RESPONSE THEORY

    DEFF Research Database (Denmark)

    Bak, Keld L.; Jørgensen, Poul; Jensen, H.J.A.

    1992-01-01

    A new scheme for obtaining first-order nonadiabatic coupling matrix elements (FO-NACME) for multiconfigurational self-consistent-field (MCSCF) wave functions is presented. The FO-NACME are evaluated from residues of linear response functions. The residues involve the geometrical response of a ref......A new scheme for obtaining first-order nonadiabatic coupling matrix elements (FO-NACME) for multiconfigurational self-consistent-field (MCSCF) wave functions is presented. The FO-NACME are evaluated from residues of linear response functions. The residues involve the geometrical response...... to the full configuration interaction limit. Comparisons are made with state-averaged MCSCF results for MgH2 and finite-difference configuration interaction by perturbation with multiconfigurational zeroth-order wave function reflected by interactive process (CIPSI) results for BH....

  20. Dissociation and psychosis in dissociative identity disorder and schizophrenia.

    Science.gov (United States)

    Laddis, Andreas; Dell, Paul F

    2012-01-01

    Dissociative symptoms, first-rank symptoms of schizophrenia, and delusions were assessed in 40 schizophrenia patients and 40 dissociative identity disorder (DID) patients with the Multidimensional Inventory of Dissociation (MID). Schizophrenia patients were diagnosed with the Structured Clinical Interview for the DSM-IV Axis I Disorders; DID patients were diagnosed with the Structured Clinical Interview for DSM-IV Dissociative Disorders-Revised. DID patients obtained significantly (a) higher dissociation scores; (b) higher passive-influence scores (first-rank symptoms); and (c) higher scores on scales that measure child voices, angry voices, persecutory voices, voices arguing, and voices commenting. Schizophrenia patients obtained significantly higher delusion scores than did DID patients. What is odd is that the dissociation scores of schizophrenia patients were unrelated to their reports of childhood maltreatment. Multiple regression analyses indicated that 81% of the variance in DID patients' dissociation scores was predicted by the MID's Ego-Alien Experiences Scale, whereas 92% of the variance in schizophrenia patients' dissociation scores was predicted by the MID's Voices Scale. We propose that schizophrenia patients' responses to the MID do not index the same pathology as do the responses of DID patients. We argue that neither phenomenological definitions of dissociation nor the current generation of dissociation instruments (which are uniformly phenomenological in nature) can distinguish between the dissociative phenomena of DID and what we suspect are just the dissociation-like phenomena of schizophrenia.

  1. Theory of fast (nonadiabatic) nuclear rotation

    International Nuclear Information System (INIS)

    Nosov, V.G.; Kamchatnov, A.M.

    1977-01-01

    The theory of backbending is developed taking into accout the increasing role of nonadiabatic effects, which are concerned with quantum number K violation. Above the transition point, rotation quantum number j (>=) jsub(c) (second-kind transition point), all possible values of the quantity K in the interval -J ( Jsub(c) are obtained. The radius of global nucleon mass distribution in the nucleus is defined from the analysis of the experimental moments of inertia in n-phase. It is in agreement with the radius of distribution of protons alone obtained from electron scattering on nuclei. Assuming the simplest singularity of parametric derivative of the Hamiltonian of the system the general theory of non-temperature (ground state)second-kind phase transitions is developed

  2. A finite-element visualization of quantum reactive scattering. II. Nonadiabaticity on coupled potential energy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Warehime, Mick [Chemical Physics Program, University of Maryland, College Park, Maryland 20742-2021 (United States); Kłos, Jacek; Alexander, Millard H., E-mail: mha@umd.edu [Department of Chemistry and Biochemistry and Institute of Physical Science and Technology, University of Maryland, College Park, Maryland 20742-2021 (United States)

    2015-01-21

    This is the second in a series of papers detailing a MATLAB based implementation of the finite element method applied to collinear triatomic reactions. Here, we extend our previous work to reactions on coupled potential energy surfaces. The divergence of the probability current density field associated with the two electronically adiabatic states allows us to visualize in a novel way where and how nonadiabaticity occurs. A two-dimensional investigation gives additional insight into nonadiabaticity beyond standard one-dimensional models. We study the F({sup 2}P) + HCl and F({sup 2}P) + H{sub 2} reactions as model applications. Our publicly available code (http://www2.chem.umd.edu/groups/alexander/FEM) is general and easy to use.

  3. Nascent energy distribution of the Criegee intermediate CH2OO from direct dynamics calculations of primary ozonide dissociation

    Science.gov (United States)

    Pfeifle, Mark; Ma, Yong-Tao; Jasper, Ahren W.; Harding, Lawrence B.; Hase, William L.; Klippenstein, Stephen J.

    2018-05-01

    Ozonolysis produces chemically activated carbonyl oxides (Criegee intermediates, CIs) that are either stabilized or decompose directly. This branching has an important impact on atmospheric chemistry. Prior theoretical studies have employed statistical models for energy partitioning to the CI arising from dissociation of the initially formed primary ozonide (POZ). Here, we used direct dynamics simulations to explore this partitioning for decomposition of c-C2H4O3, the POZ in ethylene ozonolysis. A priori estimates for the overall stabilization probability were then obtained by coupling the direct dynamics results with master equation simulations. Trajectories were initiated at the concerted cycloreversion transition state, as well as the second transition state of a stepwise dissociation pathway, both leading to a CI (H2COO) and formaldehyde (H2CO). The resulting CI energy distributions were incorporated in master equation simulations of CI decomposition to obtain channel-specific stabilized CI (sCI) yields. Master equation simulations of POZ formation and decomposition, based on new high-level electronic structure calculations, were used to predict yields for the different POZ decomposition channels. A non-negligible contribution of stepwise POZ dissociation was found, and new mechanistic aspects of this pathway were elucidated. By combining the trajectory-based channel-specific sCI yields with the channel branching fractions, an overall sCI yield of (48 ± 5)% was obtained. Non-statistical energy release was shown to measurably affect sCI formation, with statistical models predicting significantly lower overall sCI yields (˜30%). Within the range of experimental literature values (35%-54%), our trajectory-based calculations favor those clustered at the upper end of the spectrum.

  4. Nascent energy distribution of the Criegee intermediate CH2OO from direct dynamics calculations of primary ozonide dissociation.

    Science.gov (United States)

    Pfeifle, Mark; Ma, Yong-Tao; Jasper, Ahren W; Harding, Lawrence B; Hase, William L; Klippenstein, Stephen J

    2018-05-07

    Ozonolysis produces chemically activated carbonyl oxides (Criegee intermediates, CIs) that are either stabilized or decompose directly. This branching has an important impact on atmospheric chemistry. Prior theoretical studies have employed statistical models for energy partitioning to the CI arising from dissociation of the initially formed primary ozonide (POZ). Here, we used direct dynamics simulations to explore this partitioning for decomposition of c-C 2 H 4 O 3 , the POZ in ethylene ozonolysis. A priori estimates for the overall stabilization probability were then obtained by coupling the direct dynamics results with master equation simulations. Trajectories were initiated at the concerted cycloreversion transition state, as well as the second transition state of a stepwise dissociation pathway, both leading to a CI (H 2 COO) and formaldehyde (H 2 CO). The resulting CI energy distributions were incorporated in master equation simulations of CI decomposition to obtain channel-specific stabilized CI (sCI) yields. Master equation simulations of POZ formation and decomposition, based on new high-level electronic structure calculations, were used to predict yields for the different POZ decomposition channels. A non-negligible contribution of stepwise POZ dissociation was found, and new mechanistic aspects of this pathway were elucidated. By combining the trajectory-based channel-specific sCI yields with the channel branching fractions, an overall sCI yield of (48 ± 5)% was obtained. Non-statistical energy release was shown to measurably affect sCI formation, with statistical models predicting significantly lower overall sCI yields (∼30%). Within the range of experimental literature values (35%-54%), our trajectory-based calculations favor those clustered at the upper end of the spectrum.

  5. Structural Influence on Excited State Dynamics in Simple Amines

    DEFF Research Database (Denmark)

    Klein, Liv Bærenholdt

    experiments with calculations, provides new insight into the nature of the internal conversion processes that mediate the dynamical evolution between Rydberg states, and how structural variations in simple amine system have a large impact on the non-adiabatic processes. The experimental method of choice...... is femtosecond time-resolved photoelectron velocity map imaging (VMI), which is a newtechnique in the Copenhagen lab. The design, building and implementation of the VMI spectrometer has been a very substantial part of the thesis work. This techniques oers enhanced information content in the form of ecient...... and sensitive collection of photoelectron spectra. In particular, the angleresolved data available from the VMI approach provides highly detailed mechanistic insight about the relaxation pathways. One striking novel nding is that for tertiary amines, the critical factor driving the non-adiabatic dynamics...

  6. Propagation and diffusion-limited extinction of nonadiabatic heterogeneous flame in the SHS process

    International Nuclear Information System (INIS)

    Makino, Atsushi

    1994-01-01

    Nonadiabatic heterogeneous flame propagation and extinction in self-propagating high-temperature synthesis (SHS) are analyzed based on a premixed mode of propagation for the bulk flame supported by the nonpremixed reaction of dispersed nonmetals in the liquid metal. The formulation allows for volumetric heat loss throughout the bulk flame, finite-rate Arrhenius reaction at the particle surface, and temperature-sensitive Arrhenius mass diffusion in the liquid. Results show that, subsequent to melting of the metal, the flame structure consists of a relatively thin diffusion-consumption/convection zone followed by a relatively thick convection-loss zone, that the flame propagation rate decreases with increasing heat loss, that at a critical heat-loss rate the flame extinguishes as indicated by the characteristic turning-point behavior, that the surface reaction is diffusion limited such that the nonlinear, temperature-sensitive nature of the system is actually a consequence of the Arrhenius mass diffusion, and that extinction is sensitively affected by the mixture ratio, the degree of dilution, the initial temperature of the compact, and the size of the nonmetal particles. An explicit expression is derived for the normalized mass burning rate, which exhibits the characteristic turning point and shows that extinction occurs when this value is reduced to e -1/2 , which is the same as that for the nonadiabatic gaseous premixed flame. It is further shown that the theoretical results agree well with available experimental data, indicating that the present formulation captures the essential features of the nonadiabatic heterogeneous SHS processes and its potential for extension to describe other SHS phenomena

  7. Site-specific dissociation dynamics of H2/D2 on Ag(111) and Co(0001) and the validity of the site-averaging model

    International Nuclear Information System (INIS)

    Hu, Xixi; Jiang, Bin; Xie, Daiqian; Guo, Hua

    2015-01-01

    Dissociative chemisorption of polyatomic molecules on metal surfaces involves high-dimensional dynamics, of which quantum mechanical treatments are computationally challenging. A promising reduced-dimensional approach approximates the full-dimensional dynamics by a weighted average of fixed-site results. To examine the performance of this site-averaging model, we investigate two distinct reactions, namely, hydrogen dissociation on Co(0001) and Ag(111), using accurate first principles potential energy surfaces (PESs). The former has a very low barrier of ∼0.05 eV while the latter is highly activated with a barrier of ∼1.15 eV. These two systems allow the investigation of not only site-specific dynamical behaviors but also the validity of the site-averaging model. It is found that the reactivity is not only controlled by the barrier height but also by the topography of the PES. Moreover, the agreement between the site-averaged and full-dimensional results is much better on Ag(111), though quantitative in neither system. Further quasi-classical trajectory calculations showed that the deviations can be attributed to dynamical steering effects, which are present in both reactions at all energies

  8. Nonadiabatic quantum Vlasov equation for Schwinger pair production

    International Nuclear Information System (INIS)

    Kim, Sang Pyo; Schubert, Christian

    2011-01-01

    Using Lewis-Riesenfeld theory, we derive an exact nonadiabatic master equation describing the time evolution of the QED Schwinger pair-production rate for a general time-varying electric field. This equation can be written equivalently as a first-order matrix equation, as a Vlasov-type integral equation, or as a third-order differential equation. In the last version it relates to the Korteweg-de Vries equation, which allows us to construct an exact solution using the well-known one-soliton solution to that equation. The case of timelike delta function pulse fields is also briefly considered.

  9. Multiphoton ionization as a probe of molecular photofragmentation: statistical and dynamical energy partitioning in the multiphoton dissociation of nitromethane

    International Nuclear Information System (INIS)

    Rockney, B.H.

    1982-01-01

    Multiphoton ionization (MPI) appears in its first use as a probe of laser-induced photofragmentation. Specifically, MPI here reveals the internal and translational energy content of the nascent fragments from the infrared multiphoton dissociation (MPD) of nitromethane (CH 3 NO 2 ). The apparatus for this work consists of a pulsed supersonic molecular beam crossed by two pulsed and focused lasers - a CO 2 laser to induce collision-free unimolecular dissociation of CH 3 NO 2 , and a tunable dye laser following immediately to ionize selectively one of the pair of dissociation fragments for detection by a mass spectrometer and particle multiplier. A computer simulation of each fragment's MPI spectrum, a series of four photon resonances to members of the npsigma/sub u/ Rydberg state of NO 2 and three photon resonances to two vibrational members of the #betta# 1 Rydberg state of CH 3 , aids in determining the fragment's internal energy content. The dye laser is delayed and its focus is traced through a small quarter circle centered at the focus of the CO 2 laser. The flight times of the fragments from the point of dissociation and their laboratory scattering angular distributions at fixed ionizing laser wavelength provide their center of mass recoil velocity distributions. The energy deposited in the fragments evidences a striking mixture of statistical and dynamical energy partitioning. The statistical RRKM theory of unimolecular decomposition accurately predicts the amount of internal energy found in the fragments

  10. Photodynamics of oxybenzone sunscreen: Nonadiabatic dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chun-Xiang; Guo, Wei-Wei; Xie, Bin-Bin; Cui, Ganglong, E-mail: ganglong.cui@bnu.edu.cn [Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875 (China)

    2016-08-21

    Herein we have used combined static electronic structure calculations and “on-the-fly” global-switching trajectory surface-hopping dynamics simulations to explore the photochemical mechanism of oxybenzone sunscreen. We have first employed the multi-configurational CASSCF method to optimize minima, conical intersections, and minimum-energy reaction paths related to excited-state intramolecular proton transfer (ESIPT) and excited-state decays in the {sup 1}ππ{sup ∗}, {sup 1}nπ{sup ∗}, and S{sub 0} states (energies are refined at the higher MS-CASPT2 level). According to the mapped potential energy profiles, we have identified two ultrafast excited-state deactivation pathways for the initially populated {sup 1}ππ{sup ∗} system. The first is the diabatic ESIPT process along the {sup 1}ππ{sup ∗} potential energy profile. The generated {sup 1}ππ{sup ∗} keto species then decays to the S{sub 0} state via the keto {sup 1}ππ{sup ∗}/gs conical intersection. The second is internal conversion to the dark {sup 1}nπ{sup ∗} state near the {sup 1}ππ{sup ∗} /{sup 1}nπ{sup ∗} crossing point in the course of the diabatic {sup 1}ππ{sup ∗} ESIPT process. Our following dynamics simulations have shown that the ESIPT and {sup 1}ππ{sup ∗} → S{sub 0} internal conversion times are 104 and 286 fs, respectively. Finally, our present work demonstrates that in addition to the ESIPT process and the {sup 1}ππ{sup ∗} → S{sub 0} internal conversion in the keto region, the {sup 1}ππ{sup ∗} → {sup 1}nπ{sup ∗} internal conversion in the enol region plays as well an important role for the excited-state relaxation dynamics of oxybenzone.

  11. An accurate full-dimensional potential energy surface for H-Au(111): Importance of nonadiabatic electronic excitation in energy transfer and adsorption.

    Science.gov (United States)

    Janke, Svenja M; Auerbach, Daniel J; Wodtke, Alec M; Kandratsenka, Alexander

    2015-09-28

    We have constructed a potential energy surface (PES) for H-atoms interacting with fcc Au(111) based on fitting the analytic form of the energy from Effective Medium Theory (EMT) to ab initio energy values calculated with density functional theory. The fit used input from configurations of the H-Au system with Au atoms at their lattice positions as well as configurations with the Au atoms displaced from their lattice positions. It reproduces the energy, in full dimension, not only for the configurations used as input but also for a large number of additional configurations derived from ab initio molecular dynamics (AIMD) trajectories at finite temperature. Adiabatic molecular dynamics simulations on this PES reproduce the energy loss behavior of AIMD. EMT also provides expressions for the embedding electron density, which enabled us to develop a self-consistent approach to simulate nonadiabatic electron-hole pair excitation and their effect on the motion of the incident H-atoms. For H atoms with an energy of 2.7 eV colliding with Au, electron-hole pair excitation is by far the most important energy loss pathway, giving an average energy loss ≈3 times that of the adiabatic case. This increased energy loss enhances the probability of the H-atom remaining on or in the Au slab by a factor of 2. The most likely outcome for H-atoms that are not scattered also depends prodigiously on the energy transfer mechanism; for the nonadiabatic case, more than 50% of the H-atoms which do not scatter are adsorbed on the surface, while for the adiabatic case more than 50% pass entirely through the 4 layer simulation slab.

  12. Constructing quantum dynamics from mixed quantum-classical descriptions

    International Nuclear Information System (INIS)

    Barsegov, V.; Rossky, P.J.

    2004-01-01

    The influence of quantum bath effects on the dynamics of a quantum two-level system linearly coupled to a harmonic bath is studied when the coupling is both diagonal and off-diagonal. It is shown that the pure dephasing kernel and the non-adiabatic quantum transition rate between Born-Oppenheimer states of the subsystem can be decomposed into a contribution from thermally excited bath modes plus a zero point energy contribution. This quantum rate can be modewise factorized exactly into a product of a mixed quantum subsystem-classical bath transition rate and a quantum correction factor. This factor determines dynamics of quantum bath correlations. Quantum bath corrections to both the transition rate and the pure dephasing kernel are shown to be readily evaluated via a mixed quantum-classical simulation. Hence, quantum dynamics can be recovered from a mixed quantum-classical counterpart by incorporating the missing quantum bath corrections. Within a mixed quantum-classical framework, a simple approach for evaluating quantum bath corrections in calculation of the non-adiabatic transition rate is presented

  13. Calculation of decay widths of pp{mu}{sub {nu}}{sub ,J}{sup *} ion in non-adiabatic approach

    Energy Technology Data Exchange (ETDEWEB)

    Gheisari, R. [Persian Gulf Univ., Physics Dept., Bushehr (Iran, Islamic Republic of)

    2009-06-15

    We calculate decay widths of the metastable pp{mu}{sub {nu}}{sub ,J}{sup *} molecular ion in non-adiabatic approach. The muonic molecular ion can be formed in collision of the excited p{mu}(2s) atoms with H{sub 2}. Then, the decay of the pp{mu}{sub {nu}}{sub ,J}{sup *} system opens a path for the muon from p{mu}(2s) to p{mu}(1s). We employ trial wave function which includes non-adiabatic terms to calculate some radiationless decay widths. The present results of the widths do not agree well with those given in our previous work, however they are more close to recent data of other researchers. (author)

  14. Coulomb Repulsion Effect in Two-electron Non-adiabatic Tunneling through a One-level redox Molecule

    DEFF Research Database (Denmark)

    Medvedev, Igor M.; Kuznetsov, Alexander M.; Ulstrup, Jens

    2009-01-01

    We investigated Coulomb repulsion effects in nonadiabatic (diabatic) two-electron tunneling through a redox molecule with a single electronic level in a symmetric electrochemical contact under ambient conditions, i.e., room temperature and condensed matter environment. The electrochemical contact...

  15. Site-specific dissociation dynamics of H{sub 2}/D{sub 2} on Ag(111) and Co(0001) and the validity of the site-averaging model

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xixi [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Jiang, Bin [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Department of Chemical Physics, University of Science and Technology of China, Hefei 230026 (China); Xie, Daiqian, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Guo, Hua, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2015-09-21

    Dissociative chemisorption of polyatomic molecules on metal surfaces involves high-dimensional dynamics, of which quantum mechanical treatments are computationally challenging. A promising reduced-dimensional approach approximates the full-dimensional dynamics by a weighted average of fixed-site results. To examine the performance of this site-averaging model, we investigate two distinct reactions, namely, hydrogen dissociation on Co(0001) and Ag(111), using accurate first principles potential energy surfaces (PESs). The former has a very low barrier of ∼0.05 eV while the latter is highly activated with a barrier of ∼1.15 eV. These two systems allow the investigation of not only site-specific dynamical behaviors but also the validity of the site-averaging model. It is found that the reactivity is not only controlled by the barrier height but also by the topography of the PES. Moreover, the agreement between the site-averaged and full-dimensional results is much better on Ag(111), though quantitative in neither system. Further quasi-classical trajectory calculations showed that the deviations can be attributed to dynamical steering effects, which are present in both reactions at all energies.

  16. Dissociative absorption: An empirically unique, clinically relevant, dissociative factor.

    Science.gov (United States)

    Soffer-Dudek, Nirit; Lassri, Dana; Soffer-Dudek, Nir; Shahar, Golan

    2015-11-01

    Research of dissociative absorption has raised two questions: (a) Is absorption a unique dissociative factor within a three-factor structure, or a part of one general dissociative factor? Even when three factors are found, the specificity of the absorption factor is questionable. (b) Is absorption implicated in psychopathology? Although commonly viewed as "non-clinical" dissociation, absorption was recently hypothesized to be specifically associated with obsessive-compulsive symptoms. To address these questions, we conducted exploratory and confirmatory factor analyses on 679 undergraduates. Analyses supported the three-factor model, and a "purified" absorption scale was extracted from the original inclusive absorption factor. The purified scale predicted several psychopathology scales. As hypothesized, absorption was a stronger predictor of obsessive-compulsive symptoms than of general psychopathology. In addition, absorption was the only dissociative scale that longitudinally predicted obsessive-compulsive symptoms. We conclude that absorption is a unique and clinically relevant dissociative tendency that is particularly meaningful to obsessive-compulsive symptoms. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Imaging correlated three-particle continuum states. Experiment and theory on the non-adiabatic projection of bound triatomic hydrogen into three separated atoms

    International Nuclear Information System (INIS)

    Fechner, Peer Cornelis

    2015-01-01

    The central topic of this thesis is the experimental observation and the theoretical modeling of non-adiabatic three-body dissociation of H_3 and D_3 neutral triatomic hydrogen molecules. Our goal is to lend a meaning to the observed momentum vector correlation (MVC) of the three emerging ground state hydrogen atoms, for example H_3→H(1s)+H(1s)+H(1s), in terms of symmetries of the nuclear molecular wave function and of the non-adiabatic coupling which initiates this decay. In many experiments carried out over the years, a wealth of state specific MVCs was collected by different research groups. The MVCs are imaged in form of so-called Dalitz plots which show a rich structure of maxima and nodal lines, depending on the initial state of the triatomic hydrogen neutral. Theory was slow to catch up with experiment and only by this year, 2015, a general agreement was accomplished. Nevertheless, these models lack of an easy understanding of the underlying physics as many numerical calculations are involved. The theoretical model presented in this thesis follows a different approach which is more guided by the imaging character of our experiments. We concentrate on a rather qualitative treatment by limiting ourselves to the essential ingredients only. This proceeding contributes to giving a physical interpretation of the structures in the Dalitz plots in the following form: Three-particle coincident imaging offers a direct view of the emerging spatial continuum wave function of a predissociating triatomic molecule as it evolves from molecular spatial dimensions into the realm of independent free particles. This latter result is discussed in the context of the so-called Imaging Theorem, the second main part of this work. A third major part of this thesis pertains to obtaining molecular momentum wave functions in separated degrees-of-freedom via Fourier transformation. Even for triatomic hydrogen - the most simple polyatomic molecule - this is a challenging task. The

  18. Dissociative symptoms and dissociative disorder comorbidity in patients with obsessive-compulsive disorder.

    Science.gov (United States)

    Belli, Hasan; Ural, Cenk; Vardar, Melek Kanarya; Yesılyurt, Sema; Oncu, Fatıh

    2012-10-01

    The present study attempted to assess the dissociative symptoms and overall dissociative disorder comorbidity in patients with obsessive-compulsive disorder (OCD). In addition, we examined the relationship between the severity of obsessive-compulsive symptoms and dissociative symptoms. All patients admitted for the first time to the psychiatric outpatient unit were included in the study. Seventy-eight patients had been diagnosed as having OCD during the 2-year study period. Patients had to meet the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for OCD. Most (76.9%; n = 60) of the patients were female, and 23.1% (n = 18) of the patients were male. Dissociation Questionnaire was used to measure dissociative symptoms. The Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Dissociative Disorders interviews and Yale-Brown Obsessive Compulsive Checklist and Severity Scale were used. Eleven (14%) of the patients with OCD had comorbid dissociative disorder. The most prevalent disorder in our study was dissociative depersonalization disorder. Dissociative amnesia and dissociative identity disorder were common as well. The mean Yale-Brown score was 23.37 ± 7.27 points. Dissociation Questionnaire scores were between 0.40 and 3.87 points, and the mean was 2.23 ± 0.76 points. There was a statistically significant positive correlation between Yale-Brown points and Dissociation Questionnaire points. We conclude that dissociative symptoms among patients with OCD should alert clinicians for the presence of a chronic and complex dissociative disorder. Clinicians may overlook an underlying dissociative process in patients who have severe symptoms of OCD. However, a lack of adequate response to cognitive-behavioral and drug therapy may be a consequence of dissociative process. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Fragmentation dynamics of ionized neon clusters (Ne(n), n=3-14) embedded in helium nanodroplets.

    Science.gov (United States)

    Bonhommeau, David; Halberstadt, Nadine; Viel, Alexandra

    2006-01-14

    We report a theoretical study of the nonadiabatic fragmentation dynamics of ionized neon clusters embedded in helium nanodroplets for cluster sizes up to n=14 atoms. The dynamics of the neon atoms is modeled using the molecular dynamics with quantum transitions method of Tully [J. Chem. Phys. 93, 1061 (1990)] with the nuclei treated classically and transitions between electronic states quantum mechanically. The potential-energy surfaces are derived from a diatomics-in-molecules model to which induced dipole-induced dipole interactions are added. The effect of the spin-orbit interaction is also discussed. The helium environment is modeled by a friction force acting on charged atoms whose speed exceeds the critical Landau velocity. The dependence of the fragment size distribution on the friction strength and on the initial nanodroplet size is investigated. By comparing with the available experimental data obtained for Ne3+ and Ne4+, a reasonable value for the friction coefficient, the only parameter of the model, is deduced. This value is then used to predict the effect of the helium environment on the dissociation dynamics of larger neon clusters, n=5-14. The results show stabilization of larger fragments than in the gas phase, but fragmentation is not completely caged. In addition, two types of dynamics are characterized for Ne4+: fast and explosive, therefore leaving no time for friction to cool down the process when dynamics starts on one of the highest electronic states, and slower, therefore leading to some stabilization by helium when it starts on one of the lowest electronic states.

  20. Influence of the van der Waals interaction in the dissociation dynamics of N{sub 2} on W(110) from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Gondre, L. [Institut UTINAM-CNRS UMR 6213, Université de Franche-Comté, 16 Route de Gray, 25030 Besançon Cedex (France); Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián (Spain); Juaristi, J. I. [Departamento de Física de Materiales, Facultad de Químicas (UPV/EHU), Apartado 1072, 20080 Donostia-San Sebastián (Spain); Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián (Spain); Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián (Spain); Blanco-Rey, M. [Departamento de Física de Materiales, Facultad de Químicas (UPV/EHU), Apartado 1072, 20080 Donostia-San Sebastián (Spain); Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián (Spain); Díez Muiño, R.; Alducin, M. [Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián (Spain); Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián (Spain)

    2015-02-21

    Using ab initio molecular dynamics (AIMD) calculations, we investigate the role of the van der Waals (vdW) interaction in the dissociative adsorption of N{sub 2} on W(110). Hitherto, existing classical dynamics calculations performed on six-dimensional potential energy surfaces based on density functional theory (DFT), and the semi-local PW91 and RPBE [Hammer et al. Phys. Rev. B 59, 7413 (1999)] exchange-correlation functionals were unable to fully describe the dependence of the initial sticking coefficient on the molecular beam incidence conditions as found in experiments. N{sub 2} dissociation on W(110) was shown to be very sensitive not only to short molecule-surface distances but also to large distances where the vdW interaction, not included in semilocal-DFT, should dominate. In this work, we perform a systematic study on the dissociative adsorption using a selection of existing non-local functionals that include the vdW interaction (vdW-functionals). Clearly, the inclusion of the non-local correlation term contributes in all cases to correct the unrealistic energy barriers that were identified in the RPBE at large molecule-surface distances. Among the tested vdW-functionals, the original vdW-DF by Dion et al. [Phys. Rev. Lett. 92, 246401 (2004)] and the ulterior vdW-DF2 give also an adequate description of the N{sub 2} adsorption energy and energy barrier at the transition state, i.e., of the properties that are commonly used to verify the quality of any exchange-correlation functional. However, the results of our AIMD calculations, which are performed at different incidence conditions and hence extensively probe the multi-configurational potential energy surface of the system, do not seem as satisfactory as the preliminary static analysis suggested. When comparing the obtained dissociation probabilities with existing experimental data, none of the used vdW-functionals seems to provide altogether an adequate description of the N{sub 2}/W(110) interaction at

  1. Multireference theoretical investigation on selectivity of the bond fissions in photodissociation of acetyl cyanide

    Science.gov (United States)

    Xiao, Hong-Yan; Liu, Ya-Jun; Fang, Wei-Hai

    2007-12-01

    The selectivity of the C -CH3 and C-CN bond fissions upon excitation of acetyl cyanide at 193nm has been investigated at the theoretical level of multistate complete active space self-consistent field second order perturbation. The calculated results indicated that the initially excited S3 state relaxes to S2 via ultrafast internal conversion. The S2 state could dissociate via two pathways. One, adiabatically dissociates to CH3CO(X˜)+CN(Ã). The other one internally converts to S1 before S1 intersystem crossing to T1. The T1 state subsequently dissociates to two groups of products: CH3(X˜)+OCCN(X˜) and CH3CO(X˜)+CN(X˜). The experimentally observed preference branching of CN elimination over CH3 one and bond selectivity are the results of the competition between the adiabatic and nonadiabatic dynamics of the S2 state.

  2. INTRODUCING CAFein, A NEW COMPUTATIONAL TOOL FOR STELLAR PULSATIONS AND DYNAMIC TIDES

    International Nuclear Information System (INIS)

    Valsecchi, F.; Farr, W. M.; Willems, B.; Rasio, F. A.; Kalogera, V.

    2013-01-01

    Here we present CAFein, a new computational tool for investigating radiative dissipation of dynamic tides in close binaries and of non-adiabatic, non-radial stellar oscillations in isolated stars in the linear regime. For the latter, CAFein computes the non-adiabatic eigenfrequencies and eigenfunctions of detailed stellar models. The code is based on the so-called Riccati method, a numerical algorithm that has been successfully applied to a variety of stellar pulsators, and which does not suffer from the major drawbacks of commonly used shooting and relaxation schemes. Here we present an extension of the Riccati method to investigate dynamic tides in close binaries. We demonstrate CAFein's capabilities as a stellar pulsation code both in the adiabatic and non-adiabatic regimes, by reproducing previously published eigenfrequencies of a polytrope, and by successfully identifying the unstable modes of a stellar model in the β Cephei/SPB region of the Hertzsprung-Russell diagram. Finally, we verify CAFein's behavior in the dynamic tides regime by investigating the effects of dynamic tides on the eigenfunctions and orbital and spin evolution of massive main sequence stars in eccentric binaries, and of hot Jupiter host stars. The plethora of asteroseismic data provided by NASA's Kepler satellite, some of which include the direct detection of tidally excited stellar oscillations, make CAFein quite timely. Furthermore, the increasing number of observed short-period detached double white dwarfs (WDs) and the observed orbital decay in the tightest of such binaries open up a new possibility of investigating WD interiors through the effects of tides on their orbital evolution

  3. Force and Stress along Simulated Dissociation Pathways of Cucurbituril-Guest Systems.

    Science.gov (United States)

    Velez-Vega, Camilo; Gilson, Michael K

    2012-03-13

    The field of host-guest chemistry provides computationally tractable yet informative model systems for biomolecular recognition. We applied molecular dynamics simulations to study the forces and mechanical stresses associated with forced dissociation of aqueous cucurbituril-guest complexes with high binding affinities. First, the unbinding transitions were modeled with constant velocity pulling (steered dynamics) and a soft spring constant, to model atomic force microscopy (AFM) experiments. The computed length-force profiles yield rupture forces in good agreement with available measurements. We also used steered dynamics with high spring constants to generate paths characterized by a tight control over the specified pulling distance; these paths were then equilibrated via umbrella sampling simulations and used to compute time-averaged mechanical stresses along the dissociation pathways. The stress calculations proved to be informative regarding the key interactions determining the length-force profiles and rupture forces. In particular, the unbinding transition of one complex is found to be a stepwise process, which is initially dominated by electrostatic interactions between the guest's ammoniums and the host's carbonyl groups, and subsequently limited by the extraction of the guest's bulky bicyclooctane moiety; the latter step requires some bond stretching at the cucurbituril's extraction portal. Conversely, the dissociation of a second complex with a more slender guest is mainly driven by successive electrostatic interactions between the different guest's ammoniums and the host's carbonyl groups. The calculations also provide information on the origins of thermodynamic irreversibilities in these forced dissociation processes.

  4. Photofragmentation spectroscopy of stored molecular ions at the dissociation limit; Photofragmentationsspektroskopie gespeicherter Molekuelionen an der Dissoziationsschwelle

    Energy Technology Data Exchange (ETDEWEB)

    Hechtfischer, U.

    2000-07-01

    Photofragmentation spectroscopy is a sensitive probe for nonadiabatic interactions in molecular dissociation, but for molecular ions detection and analysis of spectra are often hampered by the internal excitations of the ion beam. Therefore, near-threshold photofragmentation of CH{sup +} and OH{sup +} was studied in a heavy-ion storage ring where the ions rovibronically relax to room temperature within a few seconds. In the CH{sup +} spectrum, the Feshbach resonances between the fine-structure levels of the C{sup +} fragment were observed for the first time, the complex lineshapes indicating strong nonadiabatic couplings between the potentials. By a standard single-channel analysis, the spectrum was partially assigned and a more precise dissociation energy was deduced. The complete analysis was possible by multichannel close-coupling calculations only and yielded the vibrational defects of all coupled potentials. Furthermore, improved empirical potentials were constructed by an IPA approach, and conclusions on the reverse radiative association process in interstellar clouds were drawn. In OH{sup +}, numerous photofragmentation resonances were observed for both neutral and ionic oxygen fragments and assigned to the highest bound levels of the A{sup 3}II curve. In contrast to CH{sup +}, OH{sup +} hardly shows any multichannel behavior. (orig.) [German] Photofragmentationsspektroskopie ist eine empfindliche Sonde fuer nichtadiabatische Wechselwirkungen bei der Dissoziation von Molekuelen, aber bei Molekuelionen erschweren haeufig die internen Anregungen des Ionenstrahls Messung und Analyse der Spektren. Deshalb wurde hier die schwellennahe Photofragmentation von CH{sup +}- und OH{sup +}-Molekuelionen in einem Schwerionenspeicherring untersucht, wo die Ionen rovibronisch innerhalb von Sekunden Raumtemperatur annehmen. Im CH{sup +}-Spektrum wurden so erstmals die Feshbach-Resonanzen zwischen den Feinstrukturniveaus des C{sup +}-Fragments direkt beobachtet, deren

  5. Multi-state nonadiabatic deactivation mechanism of coumarin revealed by ab initio on-the-fly trajectory surface hopping dynamic simulation.

    Science.gov (United States)

    Gan, Yanzhen; Yue, Ling; Guo, Xugeng; Zhu, Chaoyuan; Cao, Zexing

    2017-05-17

    An on-the-fly trajectory surface hopping dynamic simulation has been performed for revealing the multi-state nonadiabatic deactivation mechanism of coumarin. The mechanism involves three adiabatic excited states, S 3 (ππ*L b ), S 2 (nπ*, ππ*L a ) and S 1 (ππ*L a , nπ*), and the ground state S 0 at the four state-averaged complete active space self-consistent field, SA4-CASSCF(12,10)/6-31G* level of theory. Upon photoexcitation to the third excited state S 3 (ππ*L b ) in the Franck-Condon region, 80% sampling trajectories decay to the dark S 2 (nπ*) state within an average of 5 fs via the conical intersection S 3 (ππ*L b )/S 2 (nπ*), while 20% decay to the S 2 (ππ*L a ) state within an average of 11 fs via the conical intersection S 3 (ππ*L b )/S 2 (ππ*L a ). Then, sampling trajectories via S 2 (nπ*)/S 1 (ππ*L a ) continue with ultrafast decay processes to give a final distribution of quantum yields as follows: 42% stay on the dark S 1 (nπ*) state, 43.3% go back to the ground S 0 state, 12% undergo a ring-opening reaction to the Z-form S 0 (Z) state, and 2.7% go to the E-form S 0 (E) state. The lifetimes of the excited states are estimated as follows: the S 3 state is about 12 fs on average, the S 2 state is about 80 fs, and the S 1 state has a fast component of about 160 fs and a slow component of 15 ps. The simulated ultrafast radiationless deactivation pathways of photoexcited coumarin immediately interpret the experimentally observed weak fluorescence emission.

  6. Dynamics of production of iodine atoms by dissociation of iodides in a pulsed self-sustained discharge

    International Nuclear Information System (INIS)

    Vagin, Nikolai P; Kochetov, Igor' V; Napartovich, A P; Yuryshev, Nikolai N

    2013-01-01

    Absorption at the laser transition has been used for the first time to assess the evolution of concentration of iodine atoms in a pulsed self-sustained discharge in mixtures of iodides with a buffer gas such as molecular nitrogen and helium. Dynamics of the iodine atom production is studied by the method of absorption spectroscopy. The dissociation of C n F 2n+1 I and CnH 2n+1 I (n = 1, 2) iodides is investigated. The energy required to produce atomic iodine is evaluated. The experimental data obtained for CF 3 I are compared with the results of numerical simulations, their reasonable agreement being demonstrated. (active media)

  7. Dissociation in patients with dissociative seizures: relationships with trauma and seizure symptoms.

    Science.gov (United States)

    Pick, S; Mellers, J D C; Goldstein, L H

    2017-05-01

    This study aimed to extend the current understanding of dissociative symptoms experienced by patients with dissociative (psychogenic, non-epileptic) seizures (DS), including psychological and somatoform types of symptomatology. An additional aim was to assess possible relationships between dissociation, traumatic experiences, post-traumatic symptoms and seizure manifestations in this group. A total of 40 patients with DS were compared with a healthy control group (n = 43), matched on relevant demographic characteristics. Participants completed several self-report questionnaires, including the Multiscale Dissociation Inventory (MDI), Somatoform Dissociation Questionnaire-20, Traumatic Experiences Checklist and the Post-Traumatic Diagnostic Scale. Measures of seizure symptoms and current emotional distress (Hospital Anxiety and Depression Scale) were also administered. The clinical group reported significantly more psychological and somatoform dissociative symptoms, trauma, perceived impact of trauma, and post-traumatic symptoms than controls. Some dissociative symptoms (i.e. MDI disengagement, MDI depersonalization, MDI derealization, MDI memory disturbance, and somatoform dissociation scores) were elevated even after controlling for emotional distress; MDI depersonalization scores correlated positively with trauma scores while seizure symptoms correlated with MDI depersonalization, derealization and identity dissociation scores. Exploratory analyses indicated that somatoform dissociation specifically mediated the relationship between reported sexual abuse and DS diagnosis, along with depressive symptoms. A range of psychological and somatoform dissociative symptoms, traumatic experiences and post-traumatic symptoms are elevated in patients with DS relative to healthy controls, and seem related to seizure manifestations. Further studies are needed to explore peri-ictal dissociative experiences in more detail.

  8. Dynamics of coupled electron-nuclei-systems in laser fields; Dynamik gekoppelter Elektronen-Kern-Systeme in Laserfeldern

    Energy Technology Data Exchange (ETDEWEB)

    Falge, Mirjam

    2012-07-01

    This work aimed at the theoretical analysis of high harmonic generation in molecules and the influence of coupled electron and nuclear dynamics on ultra-short pulse ionization processes. In the first part of this thesis, the isotope effect and influence of vibrational excitation on high harmonic generation were investigated for the isotope pairs H{sub 2}O/D{sub 2}O and H{sub 2}/D{sub 2}. It was shown that on the one hand high harmonic intensities strongly depend on the vibrational quantum number of the initial state of the water molecule and on the other hand the spectra of H{sub 2}O and D{sub 2}O exhibit a clear isotope effect for certain vibrationally excited states. Also it was shown that high harmonics of vibrationally excited states show an even more pronounced isotope effect than the ground state. The second and third part of this work treats the influence of coupled electron and nuclear dynamics on photoelectron spectra. In order to facilitate a numerically exact description of this dynamics, a simple one-dimensional model system (Shin-Metiu model) was used. It consists of only a single electronic and nuclear degree-of-freedom and allows for a switching between adiabatic and strongly non-adiabatic dynamics by its parameterization. This model served for the analysis of the dynamics of three different cases ranging from weak over intermediate to strong electron-nuclear coupling. To investigate the influence of non-adiabatic effects on photoelectron spectra, time-resolved photoelectron spectra were calculated applying two methods: a numerically exact treatment and an adiabatic approach neglecting the electron-nuclear coupling. Subsequently, the dependence of the efficiency of a non-adiabatic transition on the nuclear mass was analysed. To this end, the population dynamics and photoelectron spectra were calculated numerically exactly for a strong electron and nuclear coupling. Thereafter the asymmetry in forward and backward direction of time

  9. Non-adiabatic study of the Kepler subgiant KIC 6442183

    Directory of Open Access Journals (Sweden)

    Grosjean M.

    2015-01-01

    Full Text Available Thanks to the precision of Kepler observations, [3] were able to measure the linewidth and amplitude of individual modes (including mixed modes in several subgiant power spectra. We perform a forward modelling of a Kepler subgiant based on surface properties and observed frequencies. Non-adiabatic computations including a time- dependent treatment of convection give the lifetimes of radial and non-radial modes. Next, combining the lifetimes and inertias with a stochastic excitation model gives the amplitudes of the modes. We can now directly compare theoretical and observed linewidths and amplitudes of mixed-modes to obtain new constraints on our theoretical models.

  10. Quantum Nuclear Extension of Electron Nuclear Dynamics on Folded Effective-Potential Surfaces

    DEFF Research Database (Denmark)

    Hall, B.; Deumens, E.; Ohrn, Y.

    2014-01-01

    A perennial problem in quantum scattering calculations is accurate theoretical treatment of low energy collisions. We propose a method of extracting a folded, nonadiabatic, effective potential energy surface from electron nuclear dynamics (END) trajectories; we then perform nuclear wave packet...

  11. Nonadiabatic anharmonic electron transfer

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, P. P. [Molecular Physics Research, 6547 Kristina Ursula Court, Falls Church, Virginia 22044 (United States)

    2013-03-28

    The effect of an inner sphere, local mode vibration on an electron transfer is modeled using the nonadiabatic transition probability (rate) expression together with both the anharmonic Morse and the harmonic oscillator potential. For an anharmonic inner sphere mode, a variational analysis uses harmonic oscillator basis functions to overcome the difficulties evaluating Morse-model Franck-Condon overlap factors. Individual matrix elements are computed with the use of new, fast, robust, and flexible recurrence relations. The analysis therefore readily addresses changes in frequency and/or displacement of oscillator minimums in the different electron transfer states. Direct summation of the individual Boltzmann weighted Franck-Condon contributions avoids the limitations inherent in the use of the familiar high-temperature, Gaussian form of the rate constant. The effect of harmonic versus anharmonic inner sphere modes on the electron transfer is readily seen, especially in the exoergic, inverted region. The behavior of the transition probability can also be displayed as a surface for all temperatures and values of the driving force/exoergicity {Delta}=-{Delta}G. The temperature insensitivity of the transfer rate is clearly seen when the exoergicity equals the collective reorganization energy ({Delta}={Lambda}{sub s}) along a maximum ln (w) vs. {Delta} ridge of the surface. The surface also reveals additional regions for {Delta} where ln (w) appears to be insensitive to temperature, or effectively activationless, for some kinds of inner sphere contributions.

  12. Dissociation in mediation

    Directory of Open Access Journals (Sweden)

    Daniela Muraru

    2008-01-01

    Full Text Available This paper approaches several texts that are part of the so-called discourse of mediation, adopting a pragma-dialectical perspective of the theory of dissociation. It is an attempt to identify the uses of dissociative patterns, with special emphasis on the indicators of dissociation. The paper investigates the various uses of the concept of dissociation as a discursive technique in the argumentation on the different aspects that are involved in international conflict, such as the discussion of the notion of peace. The purpose is to identify the role of dissociation, as a device strategically used by the mediator to help the parties minimize the disagreement space, and come to a conflict resolution.

  13. Ultraviolet relaxation dynamics of aniline, N, N-dimethylaniline and 3,5-dimethylaniline at 250 nm

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, James O. F.; Saalbach, Lisa; Crane, Stuart W. [Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Paterson, Martin J. [Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Townsend, Dave, E-mail: D.Townsend@hw.ac.uk [Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)

    2015-03-21

    Time-resolved photoelectron imaging was used to investigate the electronic relaxation dynamics of gas-phase aniline, N, N-dimethylaniline, and 3,5-dimethylaniline following ultraviolet excitation at 250 nm. Our analysis was supported by ab initio coupled-cluster calculations evaluating excited state energies and (in aniline) the evolution of a range of excited state physical properties as a function of N–H bond extension. Due to a lack of consistency between several earlier studies undertaken in aniline, the specific aim of this present work was to gain new insight into the previously proposed non-adiabatic coupling interaction between the two lowest lying singlet excited states S{sub 1}(ππ{sup ∗}) and S{sub 2}(3s/πσ{sup ∗}). The methyl-substituted systems N, N-dimethylaniline and 3,5-dimethylaniline were included in order to obtain more detailed dynamical information about the key internal molecular coordinates that drive the S{sub 1}(ππ{sup ∗})/S{sub 2}(3s/πσ{sup ∗}) coupling mechanism. Our findings suggest that in all three systems, both electronic states are directly populated during the initial excitation, with the S{sub 2}(3s/πσ{sup ∗}) state then potentially decaying via either direct dissociation along the N–X stretching coordinate (X = H or CH{sub 3}) or internal conversion to the S{sub 1}(ππ{sup ∗}) state. In aniline and N, N-dimethylaniline, both pathways most likely compete in the depletion of S{sub 2}(3s/πσ{sup ∗}) state population. However, in 3,5-dimethylaniline, only the direct dissociation mechanism appears to be active. This is rationalized in terms of changes in the relative rates of the two decay pathways upon methylation of the aromatic ring system.

  14. Probing the lowest coordination number of dianionic platinum-cyanide complexes in the gas phase: Dynamics of the charge dissociation process

    DEFF Research Database (Denmark)

    Bojesen, G; Hvelplund, P; Jørgensen, Thomas J. D.

    2000-01-01

    Low-energy and high-energy collision induced dissociation techniques are used to study the dissociation behavior of the gaseous Pt(CN)(6)(2-) and Pt(CN)(4)(2-) dianion complexes in order to probe the smallest stable dianion complex. Loss of neutral molecules from Pt(CN)(6)(2-) occurs resulting...... in Pt(CN)(5)(2-) and Pt(CN)(4)(2-), but no indication of the existence of Pt(CN)(3)(2-) was found. This indicates that the lifetime of Pt(CN)(3)(2-) is less than 4 mus (the flight time from the collision region to the detector). In contrast, all monoanion platinum-cyanide complexes were observed, i.......e., Pt(CN)(n)(-) (n=1-6). The kinetic energy released in processes where monoanions are formed is much lower than the barrier height for the reverse reaction (>1.5 eV), which indicates that electron detachment is involved, e.g., Pt(CN)(3)(-) and CN- are not formed in the same dynamical process from Pt(CN...

  15. Picosecond dissociation of amyloid fibrils with infrared laser: A nonequilibrium simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Hoang Viet, Man; Roland, Christopher, E-mail: cmroland@ncsu.edu; Sagui, Celeste, E-mail: sagui@ncsu.edu [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States); Derreumaux, Philippe; Nguyen, Phuong H., E-mail: phuong.nguyen@ibpc.fr [Laboratoire de Biochimie Théorique, UPR 9080, CNRS Université Denis Diderot, Sorbonne Paris Cité IBPC, 13 rue Pierre et Marie Curie, 75005 Paris (France); Li, Mai Suan [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Institute for Computational Science and Technology, SBI Building, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City (Viet Nam)

    2015-10-21

    Recently, mid-infrared free-electron laser technology has been developed to dissociate amyloid fibrils. Here, we present a theoretical framework for this type of experiment based on laser-induced nonequilibrium all-atom molecular dynamics simulations. We show that the fibril is destroyed due to the strong resonance between its amide I vibrational modes and the laser field. The effects of laser irradiation are determined by a balance between fibril formation and dissociation. While the overall rearrangements of the fibril finish over short time scales, the interaction between the peptides and the solvent continues over much longer times indicating that the waters play an important role in the dissociation process. Our results thus provide new insights into amyloid fibril dissociation by laser techniques and open up new venues to investigate the complex phenomena associated with amyloidogenesis.

  16. Amplification of weak signals via the non-adiabatic regime of stochastic resonance in a bistable dynamical system with time delay

    International Nuclear Information System (INIS)

    Du Luchun; Mei Dongcheng

    2011-01-01

    The non-adiabatic regime of stochastic resonance (SR) in a bistable system with time delay, an additive white noise and a periodic signal was investigated. The signal power amplification η was employed to characterize the SR of the system. The simulation results indicate that (i) in the case of intermediate frequency Ω of the periodic signal, the typical behavior of SR is lowered monotonically by increasing the delay time τ; in the case of large Ω, τ weakens the SR behavior and then enhances it, with a non-monotonic behavior as a function of time delay; (ii) time delay induces SR when A is above the threshold, whereas no such resonance exists in the absence of time delay; (iii) time delay induces a transition from bimodal to unimodal configuration of η; (iv) varying the particular form of time delay results in different phenomena.

  17. Nonadiabatic rate constants for proton transfer and proton-coupled electron transfer reactions in solution: Effects of quadratic term in the vibronic coupling expansion.

    Science.gov (United States)

    Soudackov, Alexander V; Hammes-Schiffer, Sharon

    2015-11-21

    Rate constant expressions for vibronically nonadiabatic proton transfer and proton-coupled electron transfer reactions are presented and analyzed. The regimes covered include electronically adiabatic and nonadiabatic reactions, as well as high-frequency and low-frequency proton donor-acceptor vibrational modes. These rate constants differ from previous rate constants derived with the cumulant expansion approach in that the logarithmic expansion of the vibronic coupling in terms of the proton donor-acceptor distance includes a quadratic as well as a linear term. The analysis illustrates that inclusion of this quadratic term in the framework of the cumulant expansion framework may significantly impact the rate constants at high temperatures for proton transfer interfaces with soft proton donor-acceptor modes that are associated with small force constants and weak hydrogen bonds. The effects of the quadratic term may also become significant in these regimes when using the vibronic coupling expansion in conjunction with a thermal averaging procedure for calculating the rate constant. In this case, however, the expansion of the coupling can be avoided entirely by calculating the couplings explicitly for the range of proton donor-acceptor distances sampled. The effects of the quadratic term for weak hydrogen-bonding systems are less significant for more physically realistic models that prevent the sampling of unphysical short proton donor-acceptor distances. Additionally, the rigorous relation between the cumulant expansion and thermal averaging approaches is clarified. In particular, the cumulant expansion rate constant includes effects from dynamical interference between the proton donor-acceptor and solvent motions and becomes equivalent to the thermally averaged rate constant when these dynamical effects are neglected. This analysis identifies the regimes in which each rate constant expression is valid and thus will be important for future applications to proton

  18. Nonadiabatic rate constants for proton transfer and proton-coupled electron transfer reactions in solution: Effects of quadratic term in the vibronic coupling expansion

    International Nuclear Information System (INIS)

    Soudackov, Alexander V.; Hammes-Schiffer, Sharon

    2015-01-01

    Rate constant expressions for vibronically nonadiabatic proton transfer and proton-coupled electron transfer reactions are presented and analyzed. The regimes covered include electronically adiabatic and nonadiabatic reactions, as well as high-frequency and low-frequency proton donor-acceptor vibrational modes. These rate constants differ from previous rate constants derived with the cumulant expansion approach in that the logarithmic expansion of the vibronic coupling in terms of the proton donor-acceptor distance includes a quadratic as well as a linear term. The analysis illustrates that inclusion of this quadratic term in the framework of the cumulant expansion framework may significantly impact the rate constants at high temperatures for proton transfer interfaces with soft proton donor-acceptor modes that are associated with small force constants and weak hydrogen bonds. The effects of the quadratic term may also become significant in these regimes when using the vibronic coupling expansion in conjunction with a thermal averaging procedure for calculating the rate constant. In this case, however, the expansion of the coupling can be avoided entirely by calculating the couplings explicitly for the range of proton donor-acceptor distances sampled. The effects of the quadratic term for weak hydrogen-bonding systems are less significant for more physically realistic models that prevent the sampling of unphysical short proton donor-acceptor distances. Additionally, the rigorous relation between the cumulant expansion and thermal averaging approaches is clarified. In particular, the cumulant expansion rate constant includes effects from dynamical interference between the proton donor-acceptor and solvent motions and becomes equivalent to the thermally averaged rate constant when these dynamical effects are neglected. This analysis identifies the regimes in which each rate constant expression is valid and thus will be important for future applications to proton

  19. Path integral density matrix dynamics: a method for calculating time-dependent properties in thermal adiabatic and non-adiabatic systems.

    Science.gov (United States)

    Habershon, Scott

    2013-09-14

    We introduce a new approach for calculating quantum time-correlation functions and time-dependent expectation values in many-body thermal systems; both electronically adiabatic and non-adiabatic cases can be treated. Our approach uses a path integral simulation to sample an initial thermal density matrix; subsequent evolution of this density matrix is equivalent to solution of the time-dependent Schrödinger equation, which we perform using a linear expansion of Gaussian wavepacket basis functions which evolve according to simple classical-like trajectories. Overall, this methodology represents a formally exact approach for calculating time-dependent quantum properties; by introducing approximations into both the imaginary-time and real-time propagations, this approach can be adapted for complex many-particle systems interacting through arbitrary potentials. We demonstrate this method for the spin Boson model, where we find good agreement with numerically exact calculations. We also discuss future directions of improvement for our approach with a view to improving accuracy and efficiency.

  20. Path integral density matrix dynamics: A method for calculating time-dependent properties in thermal adiabatic and non-adiabatic systems

    International Nuclear Information System (INIS)

    Habershon, Scott

    2013-01-01

    We introduce a new approach for calculating quantum time-correlation functions and time-dependent expectation values in many-body thermal systems; both electronically adiabatic and non-adiabatic cases can be treated. Our approach uses a path integral simulation to sample an initial thermal density matrix; subsequent evolution of this density matrix is equivalent to solution of the time-dependent Schrödinger equation, which we perform using a linear expansion of Gaussian wavepacket basis functions which evolve according to simple classical-like trajectories. Overall, this methodology represents a formally exact approach for calculating time-dependent quantum properties; by introducing approximations into both the imaginary-time and real-time propagations, this approach can be adapted for complex many-particle systems interacting through arbitrary potentials. We demonstrate this method for the spin Boson model, where we find good agreement with numerically exact calculations. We also discuss future directions of improvement for our approach with a view to improving accuracy and efficiency

  1. The co-occurrence of PTSD and dissociation: differentiating severe PTSD from dissociative-PTSD.

    Science.gov (United States)

    Armour, Cherie; Karstoft, Karen-Inge; Richardson, J Don

    2014-08-01

    A dissociative-posttraumatic stress disorder (PTSD) subtype has been included in the DSM-5. However, it is not yet clear whether certain socio-demographic characteristics or psychological/clinical constructs such as comorbid psychopathology differentiate between severe PTSD and dissociative-PTSD. The current study investigated the existence of a dissociative-PTSD subtype and explored whether a number of trauma and clinical covariates could differentiate between severe PTSD alone and dissociative-PTSD. The current study utilized a sample of 432 treatment seeking Canadian military veterans. Participants were assessed with the Clinician Administered PTSD Scale (CAPS) and self-report measures of traumatic life events, depression, and anxiety. CAPS severity scores were created reflecting the sum of the frequency and intensity items from each of the 17 PTSD and 3 dissociation items. The CAPS severity scores were used as indicators in a latent profile analysis (LPA) to investigate the existence of a dissociative-PTSD subtype. Subsequently, several covariates were added to the model to explore differences between severe PTSD alone and dissociative-PTSD. The LPA identified five classes: one of which constituted a severe PTSD group (30.5 %), and one of which constituted a dissociative-PTSD group (13.7 %). None of the included, demographic, trauma, or clinical covariates were significantly predictive of membership in the dissociative-PTSD group compared to the severe PTSD group. In conclusion, a significant proportion of individuals report high levels of dissociation alongside their PTSD, which constitutes a dissociative-PTSD subtype. Further investigation is needed to identify which factors may increase or decrease the likelihood of membership in a dissociative-PTSD subtype group compared to a severe PTSD only group.

  2. Gas hydrate dissociation off Svalbard induced by isostatic rebound rather than global warming.

    Science.gov (United States)

    Wallmann, Klaus; Riedel, M; Hong, W L; Patton, H; Hubbard, A; Pape, T; Hsu, C W; Schmidt, C; Johnson, J E; Torres, M E; Andreassen, K; Berndt, C; Bohrmann, G

    2018-01-08

    Methane seepage from the upper continental slopes of Western Svalbard has previously been attributed to gas hydrate dissociation induced by anthropogenic warming of ambient bottom waters. Here we show that sediment cores drilled off Prins Karls Foreland contain freshwater from dissociating hydrates. However, our modeling indicates that the observed pore water freshening began around 8 ka BP when the rate of isostatic uplift outpaced eustatic sea-level rise. The resultant local shallowing and lowering of hydrostatic pressure forced gas hydrate dissociation and dissolved chloride depletions consistent with our geochemical analysis. Hence, we propose that hydrate dissociation was triggered by postglacial isostatic rebound rather than anthropogenic warming. Furthermore, we show that methane fluxes from dissociating hydrates were considerably smaller than present methane seepage rates implying that gas hydrates were not a major source of methane to the oceans, but rather acted as a dynamic seal, regulating methane release from deep geological reservoirs.

  3. Non-adiabatic pressure loss boundary condition for modelling turbocharger turbine pulsating flow

    International Nuclear Information System (INIS)

    Chiong, M.S.; Rajoo, S.; Romagnoli, A.; Costall, A.W.; Martinez-Botas, R.F.

    2015-01-01

    Highlights: • Bespoke non-adiabatic pressure loss boundary for pulse flow turbine modelling. • Predictions show convincing results against experimental and literature data. • Predicted pulse pressure propagation is in good agreement with literature data. • New methodology is time efficient and requires minimal geometrical inputs. - Abstract: This paper presents a simplified methodology of pulse flow turbine modelling, as an alternative over the meanline integrated methodology outlined in previous work, in order to make its application to engine cycle simulation codes much more straight forward. This is enabled through the development of a bespoke non-adiabatic pressure loss boundary to represent the turbine rotor. In this paper, turbocharger turbine pulse flow performance predictions are presented along with a comparison of computation duration against the previously established integrated meanline method. Plots of prediction deviation indicate that the mass flow rate and actual power predictions from both methods are highly comparable and are reasonably close to experimental data. However, the new boundary condition required significantly lower computational time and rotor geometrical inputs. In addition, the pressure wave propagation in this simplified unsteady turbine model at different pulse frequencies has also been found to be in agreement with data from the literature, thereby supporting the confidence in its ability to simulate the wave action encountered in turbine pulse flow operation

  4. Theoretical studies of molecule surface scattering: Rotationally inelastic diffraction and dissociative dynamics of H2 on metals

    International Nuclear Information System (INIS)

    Cruz Pol, A.J.

    1993-01-01

    The interaction of H 2 and its isotopes with metal surfaces has been the subject of many investigations. The scattering experiments provide data such as the final rotational state distribution, sticking coefficients, kinetic energy distribution, and diffraction data. In the first study of this thesis the author implemented a model for looking at the rotationally inelastic diffraction probabilities for H 2 , HD, and D 2 , as a function of surface temperature. The surface is treated in a quantum mechanical fashion using a recently developed formalism. The center of mass translational motion is treated semiclassically using Gaussian wave packets, and the rotations are described quantum mechanically. The phonon summed rotation-diffraction probabilities as well as the probability distribution for a scattering molecule exchanging an amount of energy ΔE with the surface were computed. In the second and third study of this thesis the author implemented a mixed quantum-classical model to compute the probability for dissociation and rotational excitation for H 2 , HD, and D 2 scattered from Ni(100) dimensionally in dynamics simulations. Of the six degrees of freedom for the dissociative adsorption of a diatomic molecule on a static surface, the author treats Z,d the center of mass distance above the surface plan, r, the internuclear separation, θ, the polar orientation angle, quantum mechanically. The remaining three degrees of freedom, X and Y, the center of mass position on the surface plane, and oe, the azimuthal orientation angle, are treated classically. Probabilities for dissociation and ro-vibrational excitation are computed as a function of incident translational energy. Two sudden approximations are tested, in which either the center of mass translation parallel to the surface or the azimuthal orientation of the molecule are frozen. Comparisons are made between low and high dimensionality results and with fully classical results

  5. Dynamics of Photoexcited State of Semiconductor Quantum Dots

    Science.gov (United States)

    Trivedi, Dhara J.

    In this thesis, non-adiabatic molecular dynamics (NAMD) of excited states in semiconductor quantum dots are investigated. Nanoscale systems provide important opportunities for theory and computation for research because the experimental tools often provide an incomplete picture of the structure and/or function of nanomaterials, and theory can often fill in missing features crucial in understanding what is being measured. The simulation of NAMD is an indispensable tool for understanding complex ultrafast photoinduced processes such as charge and energy transfer, thermal relaxation, and charge recombination. Based on the state-of-the-art ab initio approaches in both the energy and time domains, the thesis presents a comprehensive discussion of the dynamical processes in quantum dots, ranging from the initial photon absorption to the final emission. We investigate the energy relaxation and transfer rates in pure and surface passivated quantum dots of different sizes. The study establishes the fundamental mechanisms of the electron and hole relaxation processes with and without hole traps. We develop and implement more accurate and efficient methods for NAMD. These methods are advantageous over the traditional ones when one encounters classically forbidden transitions. We also explore the effect of decoherence and non-adiabatic couplings on the dynamics. The results indicate significant influence on the accuracy and related computational cost of the simulated dynamics.

  6. Dissociation in Psychiatric Disorders: A Meta-Analysis of Studies Using the Dissociative Experiences Scale.

    Science.gov (United States)

    Lyssenko, Lisa; Schmahl, Christian; Bockhacker, Laura; Vonderlin, Ruben; Bohus, Martin; Kleindienst, Nikolaus

    2018-01-01

    Dissociation is a complex, ubiquitous construct in psychopathology. Symptoms of dissociation are present in a variety of mental disorders and have been connected to higher burden of illness and poorer treatment response, and not only in disorders with high levels of dissociation. This meta-analysis offers a systematic and evidence-based study of the prevalence and distribution of dissociation, as assessed by the Dissociative Experiences Scale, within different categories of mental disorders, and it updates an earlier meta-analysis. More than 1,900 original publications were screened, and 216 were included in the meta-analysis, comprising 15,219 individuals in 19 diagnostic categories. The largest mean dissociation scores were found in dissociative disorders (mean scores >35), followed by posttraumatic stress disorder, borderline personality disorder, and conversion disorder (mean scores >25). Somatic symptom disorder, substance-related and addictive disorders, feeding and eating disorders, schizophrenia, anxiety disorder, OCD, and most affective disorders also showed mean dissociation scores >15. Bipolar disorders yielded the lowest dissociation scores (mean score, 14.8). The findings underline the importance of careful psychopathological assessment of dissociative symptoms in the entire range of mental disorders.

  7. Nonadiabatic effects on surfaces: Kohn anomaly, electronic damping of adsorbate vibrations, and local heating of single molecules

    International Nuclear Information System (INIS)

    Kroeger, J

    2008-01-01

    Three aspects of electron-phonon coupling at metal surfaces are reviewed. One aspect is the Kohn effect, which describes an anomalous dispersion relation of surface phonons due to quasi-one-dimensional nesting of Fermi surface contours. The combination of electron energy loss spectroscopy and angle-resolved photoelectron spectroscopy allows us to unambiguously characterize Kohn anomaly systems. A second aspect is the nonadiabatic damping of adsorbate vibrations. Characteristic spectroscopic line shapes of vibrational modes allow us to estimate the amount of energy transfer between the vibrational mode and electron-hole pairs. Case studies of a Kohn anomaly and nonadiabatic damping are provided by the hydrogen- and deuterium-covered Mo(110) surface. As a third aspect of interaction between electrons and phonons, local heating of a C 60 molecule adsorbed on Cu(100) and in contact with the tip of a scanning tunnelling microscope is covered

  8. Geometric phase effects in excited state dynamics through a conical intersection in large molecules: N-dimensional linear vibronic coupling model study

    Science.gov (United States)

    Li, Jiaru; Joubert-Doriol, Loïc; Izmaylov, Artur F.

    2017-08-01

    We investigate geometric phase (GP) effects in nonadiabatic transitions through a conical intersection (CI) in an N-dimensional linear vibronic coupling (ND-LVC) model. This model allows for the coordinate transformation encompassing all nonadiabatic effects within a two-dimensional (2D) subsystem, while the other N - 2 dimensions form a system of uncoupled harmonic oscillators identical for both electronic states and coupled bi-linearly with the subsystem coordinates. The 2D subsystem governs ultra-fast nonadiabatic dynamics through the CI and provides a convenient model for studying GP effects. Parameters of the original ND-LVC model define the Hamiltonian of the transformed 2D subsystem and thus influence GP effects directly. Our analysis reveals what values of ND-LVC parameters can introduce symmetry breaking in the 2D subsystem that diminishes GP effects.

  9. How thioredoxin dissociates its mixed disulfide.

    Directory of Open Access Journals (Sweden)

    Goedele Roos

    2009-08-01

    Full Text Available The dissociation mechanism of the thioredoxin (Trx mixed disulfide complexes is unknown and has been debated for more than twenty years. Specifically, opposing arguments for the activation of the nucleophilic cysteine as a thiolate during the dissociation of the complex have been put forward. As a key model, the complex between Trx and its endogenous substrate, arsenate reductase (ArsC, was used. In this structure, a Cys29(Trx-Cys89(ArsC intermediate disulfide is formed by the nucleophilic attack of Cys29(Trx on the exposed Cys82(ArsC-Cys89(ArsC in oxidized ArsC. With theoretical reactivity analysis, molecular dynamics simulations, and biochemical complex formation experiments with Cys-mutants, Trx mixed disulfide dissociation was studied. We observed that the conformational changes around the intermediate disulfide bring Cys32(Trx in contact with Cys29(Trx. Cys32(Trx is activated for its nucleophilic attack by hydrogen bonds, and Cys32(Trx is found to be more reactive than Cys82(ArsC. Additionally, Cys32(Trx directs its nucleophilic attack on the more susceptible Cys29(Trx and not on Cys89(ArsC. This multidisciplinary approach provides fresh insights into a universal thiol/disulfide exchange reaction mechanism that results in reduced substrate and oxidized Trx.

  10. Induced photoemission from driven nonadiabatic dynamics in an avoided crossing system

    Energy Technology Data Exchange (ETDEWEB)

    Arasaki, Yasuki; Mizuno, Yuta; Takatsuka, Kazuo, E-mail: kaztak@mns2.c.u-tokyo.ac.jp [Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, 153-8902 Tokyo (Japan); Scheit, Simona [Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, 153-8902 Tokyo (Japan); Theoretische Chemie, Universität Heidelberg, Im Neuneheimer Feld 229, 69120 Heidelberg (Germany)

    2014-12-21

    When vibrational dynamics on an ionic state (large dipole moment) is coupled to that on a neutral state (small dipole moment) such as at an avoided crossing in the alkali halide system, the population transfer between the states cause oscillation of the molecular dipole, leading to dipole emission. Such dynamics may be driven by an external field. We study how the coupled wavepacket dynamics is affected by the parameters (intensity, frequency) of the driving field with the aim of making use of the photoemission as an alternative detection scheme of femtosecond and subfemtosecond vibrational and electronic dynamics or as a characteristic optical source.

  11. Time-resolved photoelectron spectroscopy of IR-driven electron dynamics in a charge transfer model system.

    Science.gov (United States)

    Falge, Mirjam; Fröbel, Friedrich Georg; Engel, Volker; Gräfe, Stefanie

    2017-08-02

    If the adiabatic approximation is valid, electrons smoothly adapt to molecular geometry changes. In contrast, as a characteristic of diabatic dynamics, the electron density does not follow the nuclear motion. Recently, we have shown that the asymmetry in time-resolved photoelectron spectra serves as a tool to distinguish between these dynamics [Falge et al., J. Phys. Chem. Lett., 2012, 3, 2617]. Here, we investigate the influence of an additional, moderately intense infrared (IR) laser field, as often applied in attosecond time-resolved experiments, on such asymmetries. This is done using a simple model for coupled electronic-nuclear motion. We calculate time-resolved photoelectron spectra and their asymmetries and demonstrate that the spectra directly map the bound electron-nuclear dynamics. From the asymmetries, we can trace the IR field-induced population transfer and both the field-driven and intrinsic (non-)adiabatic dynamics. This holds true when considering superposition states accompanied by electronic coherences. The latter are observable in the asymmetries for sufficiently short XUV pulses to coherently probe the coupled states. It is thus documented that the asymmetry is a measure for phases in bound electron wave packets and non-adiabatic dynamics.

  12. Predictors of trait dissociation and peritraumatic dissociation induced via cold pressor.

    Science.gov (United States)

    Gómez-Pérez, Lydia; López-Martínez, Alicia Eva; Asmundson, Gordon John Glenn

    2013-11-30

    Understanding which factors predict individual dissociative response during stressful situations is important to clarify the nature of dissociation and the mechanisms associated to its use as a coping strategy. The present study examined (1) whether experiential avoidance (EA), anxiety sensitivity (AS), depressive symptoms, and state anxiety concurrently predicted trait dissociation (TD)-absorption, amnesia, depersonalization, and total TD scores-and laboratory induced dissociation (LID); and (2) whether TD and catastrophizing predicted LID. We also examined whether catastrophizing mediated the relationships between both AS and depressive symptoms and LID. A total of 101 female undergraduate students participated in a cold pressor task, which significantly induced dissociation. Results of hierarchical regression analyses showed that AS at Time 1 (9 months before the experimental session), as well as depressive symptoms and catastrophizing at the time of the experiment (Time 2), predicted LID at Time 2. Depressive symptoms at Time 2 predicted total TD, absorption, and amnesia scores. AS at Time 1 and depressive symptoms at Time 2 predicted depersonalization. AS, depressive symptoms, and catastrophizing seem to facilitate the use of dissociative strategies by healthy individuals, even in response to non-traumatic but discomforting stress. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  13. Three dimensions of dissociative amnesia.

    Science.gov (United States)

    Dell, Paul F

    2013-01-01

    Principal axis factor analysis with promax rotation extracted 3 factors from the 42 memory and amnesia items of the Multidimensional Inventory of Dissociation (MID) database (N = 2,569): Discovering Dissociated Actions, Lapses of Recent Memory and Skills, and Gaps in Remote Memory. The 3 factors' shared variance ranged from 36% to 64%. Construed as scales, the 3 factor scales had Cronbach's alpha coefficients of .96, .94, and .93, respectively. The scales correlated strongly with mean Dissociative Experiences Scale scores, mean MID scores, and total scores on the Structured Clinical Interview for DSM-IV Dissociative Disorders-Revised (SCID-D-R). What is interesting is that the 3 amnesia factors exhibited a range of correlations with SCID-D-R Amnesia scores (.52, .63, and .70, respectively), suggesting that the SCID-D-R Amnesia score emphasizes gaps in remote memory over amnesias related to dissociative identity disorder. The 3 amnesia factor scales exhibited a clinically meaningful pattern of significant differences among dissociative identity disorder, dissociative disorder not otherwise specified-1, dissociative amnesia, depersonalization disorder, and nonclinical participants. The 3 amnesia factors may have greater clinical utility for frontline clinicians than (a) amnesia as discussed in the context of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, nosology of the dissociative disorders or (b) P. Janet's (1893/1977 ) 4-fold classification of dissociative amnesia. The author recommends systematic study of the phenomenological differences within specific dissociative symptoms and their differential relationship to specific dissociative disorders.

  14. Monte Carlo wave packet approach to dissociative multiple ionization in diatomic molecules

    DEFF Research Database (Denmark)

    Leth, Henriette Astrup; Madsen, Lars Bojer; Mølmer, Klaus

    2010-01-01

    A detailed description of the Monte Carlo wave packet technique applied to dissociative multiple ionization of diatomic molecules in short intense laser pulses is presented. The Monte Carlo wave packet technique relies on the Born-Oppenheimer separation of electronic and nuclear dynamics...... and provides a consistent theoretical framework for treating simultaneously both ionization and dissociation. By simulating the detection of continuum electrons and collapsing the system onto either the neutral, singly ionized or doubly ionized states in every time step the nuclear dynamics can be solved....... The computational effort is restricted and the model is applicable to any molecular system where electronic Born-Oppenheimer curves, dipole moment functions, and ionization rates as a function of nuclear coordinates can be determined....

  15. Nonadiabatic exchange dynamics during adiabatic frequency sweeps.

    Science.gov (United States)

    Barbara, Thomas M

    2016-04-01

    A Bloch equation analysis that includes relaxation and exchange effects during an adiabatic frequency swept pulse is presented. For a large class of sweeps, relaxation can be incorporated using simple first order perturbation theory. For anisochronous exchange, new expressions are derived for exchange augmented rotating frame relaxation. For isochronous exchange between sites with distinct relaxation rate constants outside the extreme narrowing limit, simple criteria for adiabatic exchange are derived and demonstrate that frequency sweeps commonly in use may not be adiabatic with regard to exchange unless the exchange rates are much larger than the relaxation rates. Otherwise, accurate assessment of the sensitivity to exchange dynamics will require numerical integration of the rate equations. Examples of this situation are given for experimentally relevant parameters believed to hold for in-vivo tissue. These results are of significance in the study of exchange induced contrast in magnetic resonance imaging. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. From dissociation to trauma? Individual differences in dissociation as predictor of 'trauma' perception

    NARCIS (Netherlands)

    Rassin, Eric; van Rootselaar, Anne-Fleur

    2006-01-01

    In clinical literature, dissociative complaints are generally considered to be the result of traumatic experiences. However, it has been argued that dissociative complaints, in turn, may indulge over-reporting of traumatic experiences. Hence, correlations between dissociation and self-reported

  17. Photocarrier dynamics in monolayer phosphorene and bulk black phosphorus.

    Science.gov (United States)

    Zereshki, Peymon; Wei, Yaqing; Ceballos, Frank; Bellus, Matthew Z; Lane, Samuel D; Pan, Shudi; Long, Run; Zhao, Hui

    2018-06-13

    We report a combined theoretical and experimental study on photocarrier dynamics in monolayer phosphorene and bulk black phosphorus. Samples of monolayer phosphorene and bulk black phosphorus were fabricated by mechanical exfoliation, identified according to their reflective contrasts, and protected by covering them with hexagonal boron nitride layers. Photocarrier dynamics in these samples was studied by an ultrafast pump-probe technique. The photocarrier lifetime of monolayer phosphorene was found to be about 700 ps, which is about 9 times longer than that of bulk black phosphorus. This trend was reproduced in our calculations based on ab initio nonadiabatic molecular dynamics combined with time-domain density functional theory in the Kohn-Sham representation, and can be attributed to the smaller bandgap and stronger nonadiabatic coupling in bulk. The transient absorption response was also found to be dependent on the sample orientation with respect to the pump polarization, which is consistent with the previously reported anisotropic absorption of phosphorene. In addition, an oscillating component of the differential reflection signal at early probe delays was observed in the bulk sample and was attributed to the layer-breathing phonon mode with an energy of about 1 meV and a decay time of about 1.35 ps. These results provide valuable information for application of monolayer phosphorene in optoelectronics.

  18. Ionic diffusion and salt dissociation conditions of lithium liquid crystal electrolytes.

    Science.gov (United States)

    Saito, Yuria; Hirai, Kenichi; Murata, Shuuhei; Kishii, Yutaka; Kii, Keisuke; Yoshio, Masafumi; Kato, Takashi

    2005-06-16

    Salt dissociation conditions and dynamic properties of ionic species in liquid crystal electrolytes of lithium were investigated by a combination of NMR spectra and diffusion coefficient estimations using the pulsed gradient spin-echo NMR techniques. Activation energies of diffusion (Ea) of ionic species changed with the phase transition of the electrolyte. That is, Ea of the nematic phase was lower than that of the isotropic phase. This indicates that the aligned liquid crystal molecules prepared efficient conduction pathways for migration of ionic species. The dissociation degree of the salt was lower compared with those of the conventional electrolyte solutions and polymer gel electrolytes. This is attributed to the low concentration of polar sites, which attract the dissolved salt and promote salt dissociation, on the liquid crystal molecules. Furthermore, motional restriction of the molecules due to high viscosity and molecular oriented configuration in the nematic phase caused inefficient attraction of the sites for the salt. With a decreased dissolved salt concentration of the liquid crystal electrolyte, salt dissociation proceeded, and two diffusion components attributed to the ion and ion pair were detected independently. This means that the exchange rate between the ion and the ion pair is fairly slow once the salt is dissociated in the liquid crystal electrolytes due to the low motility of the medium molecules that initiate salt dissociation.

  19. Assessment of complex dissociative disorder patients and simulated dissociation in forensic contexts.

    Science.gov (United States)

    Brand, Bethany L; Webermann, Aliya R; Frankel, A Steven

    Few assessors receive training in assessing dissociation and complex dissociative disorders (DDs). Potential differential diagnoses include anxiety, mood, psychotic, substance use, and personality disorders, as well as exaggeration and malingering. Individuals with DDs typically elevate on many clinical and validity scales on psychological tests, yet research indicates that they can be distinguished from DD simulators. Becoming informed about the testing profiles of DD individuals and DD simulators can improve the accuracy of differential diagnoses in forensic settings. In this paper, we first review the testing profiles of individuals with complex DDs and contrast them with DD simulators on assessment measures used in forensic contexts, including the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), Personality Assessment Inventory (PAI), and the Structured Inventory of Reported Symptoms (SIRS), as well as dissociation-specific measures such as the Dissociative Experiences Scale (DES) and Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D-R). We then provide recommendations for assessing complex trauma and dissociation through the aforementioned assessments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Condensation and dissociation rates for gas phase metal clusters from molecular dynamics trajectory calculations

    Science.gov (United States)

    Yang, Huan; Goudeli, Eirini; Hogan, Christopher J.

    2018-04-01

    In gas phase synthesis systems, clusters form and grow via condensation, in which a monomer binds to an existing cluster. While a hard-sphere equation is frequently used to predict the condensation rate coefficient, this equation neglects the influences of potential interactions and cluster internal energy on the condensation process. Here, we present a collision rate theory-molecular dynamics simulation approach to calculate condensation probabilities and condensation rate coefficients. We use this approach to examine atomic condensation onto 6-56-atom Au and Mg clusters. The probability of condensation depends upon the initial relative velocity (v) between atom and cluster and the initial impact parameter (b). In all cases, there is a well-defined region of b-v space where condensation is highly probable, and outside of which the condensation probability drops to zero. For Au clusters with more than 10 atoms, we find that at gas temperatures in the 300-1200 K range, the condensation rate coefficient exceeds the hard-sphere rate coefficient by a factor of 1.5-2.0. Conversely, for Au clusters with 10 or fewer atoms and for 14- and 28-atom Mg clusters, as cluster equilibration temperature increases, the condensation rate coefficient drops to values below the hard-sphere rate coefficient. Calculations also yield the self-dissociation rate coefficient, which is found to vary considerably with gas temperature. Finally, calculations results reveal that grazing (high b) atom-cluster collisions at elevated velocity (>1000 m s-1) can result in the colliding atom rebounding (bounce) from the cluster surface or binding while another atom dissociates (replacement). The presented method can be applied in developing rate equations to predict material formation and growth rates in vapor phase systems.

  1. Decisive role of nuclear quantum effects on surface mediated water dissociation at finite temperature

    Science.gov (United States)

    Litman, Yair; Donadio, Davide; Ceriotti, Michele; Rossi, Mariana

    2018-03-01

    Water molecules adsorbed on inorganic substrates play an important role in several technological applications. In the presence of light atoms in adsorbates, nuclear quantum effects (NQEs) influence the structural stability and the dynamical properties of these systems. In this work, we explore the impact of NQEs on the dissociation of water wires on stepped Pt(221) surfaces. By performing ab initio molecular dynamics simulations with van der Waals corrected density functional theory, we note that several competing minima for both intact and dissociated structures are accessible at finite temperatures, making it important to assess whether harmonic estimates of the quantum free energy are sufficient to determine the relative stability of the different states. We thus perform ab initio path integral molecular dynamics (PIMD) in order to calculate these contributions taking into account the conformational entropy and anharmonicities at finite temperatures. We propose that when adsorption is weak and NQEs on the substrate are negligible, PIMD simulations can be performed through a simple partition of the system, resulting in considerable computational savings. We then calculate the full contribution of NQEs to the free energies, including also anharmonic terms. We find that they result in an increase of up to 20% of the quantum contribution to the dissociation free energy compared with the harmonic estimates. We also find that the dissociation process has a negligible contribution from tunneling but is dominated by zero point energies, which can enhance the rate of dissociation by three orders of magnitude. Finally we highlight how both temperature and NQEs indirectly impact dipoles and the redistribution of electron density, causing work function changes of up to 0.4 eV with respect to static estimates. This quantitative determination of the change in the work function provides a possible approach to determine experimentally the most stable configurations of water

  2. Dissociation in small molecules

    International Nuclear Information System (INIS)

    Dehmer, P.M.

    1982-01-01

    The study of molecular dissociation processes is one of the most interesting areas of modern spectroscopy owing to the challenges presented bt even the simplest of diatomic molecules. This paper reviews the commonly used descriptions of molecular dissociation processes for diatomic molecules, the selection rules for predissociation, and a few of the principles to be remembered when one is forced to speculate about dissociation mechanisms in a new molecule. Some of these points will be illustrated by the example of dissociative ionization in O 2

  3. Three-body dissociations: The photodissociation of dimethyl sulfoxide at 193 nm

    International Nuclear Information System (INIS)

    Blank, D.A.; North, S.W.; Stranges, D.

    1997-01-01

    When a molecule with two equivalent chemical bonds is excited above the threshold for dissociation of both bonds, how the rupture of the two bonds is temporally coupled becomes a salient question. Following absorption at 193 nm dimethyl sulfoxide (CH 3 SOCH 3 ) contains enough energy to rupture both C-S bonds. This can happen in a stepwise (reaction 1) or concerted (reaction 2) fashion where the authors use rotation of the SOCH 3 intermediate prior to dissociation to define a stepwise dissociation: (1) CH 3 SOCH 3 → 2CH 3 + SO; (2a) CH 3 SOCH 3 → CH 3 + SOCH 3 ; and (2b) SOCH 3 → SO + CH 3 . Recently, the dissociation of dimethyl sulfoxide following absorption at 193 nm was suggested to involve simultaneous cleavage of both C-S bonds on an excited electronic surface. This conclusion was inferred from laser induced fluorescence (LIF) and resonant multiphoton ionization (2+1 REMPI) measurements of the internal energy content in the CH 3 and SO photoproducts and a near unity quantum yield measured for SO. Since this type of concerted three body dissociation is very interesting and a rather rare event in photodissociation dynamics, the authors chose to investigate this system using the technique of photofragment translational spectroscopy at beamline 9.0.2.1. The soft photoionization provided by the VUV undulator radiation allowed the authors to probe the SOCH 3 intermediate which had not been previously observed and provided good evidence that the dissociation of dimethyl sulfoxide primarily proceeds via a two step dissociation, reaction 2

  4. Control of chemical dynamics by lasers: theoretical considerations.

    Science.gov (United States)

    Kondorskiy, Alexey; Nanbu, Shinkoh; Teranishi, Yoshiaki; Nakamura, Hiroki

    2010-06-03

    Theoretical ideas are proposed for laser control of chemical dynamics. There are the following three elementary processes in chemical dynamics: (i) motion of the wave packet on a single adiabatic potential energy surface, (ii) excitation/de-excitation or pump/dump of wave packet, and (iii) nonadiabatic transitions at conical intersections of potential energy surfaces. A variety of chemical dynamics can be controlled, if we can control these three elementary processes as we desire. For (i) we have formulated the semiclassical guided optimal control theory, which can be applied to multidimensional real systems. The quadratic or periodic frequency chirping method can achieve process (ii) with high efficiency close to 100%. Concerning process (iii) mentioned above, the directed momentum method, in which a predetermined momentum vector is given to the initial wave packet, makes it possible to enhance the desired transitions at conical intersections. In addition to these three processes, the intriguing phenomenon of complete reflection in the nonadiabatic-tunneling-type of potential curve crossing can also be used to control a certain class of chemical dynamics. The basic ideas and theoretical formulations are provided for the above-mentioned processes. To demonstrate the effectiveness of these controlling methods, numerical examples are shown by taking the following processes: (a) vibrational photoisomerization of HCN, (b) selective and complete excitation of the fine structure levels of K and Cs atoms, (c) photoconversion of cyclohexadiene to hexatriene, and (d) photodissociation of OHCl to O + HCl.

  5. Classical and macroquantum dynamics of charged particles in a magnetic field

    International Nuclear Information System (INIS)

    Varma, R.K.

    2003-01-01

    The investigations relating to the dynamics of charged particles in a magnetic field carried out over more than 40 years have been reviewed with special reference to the problem of nonadiabaticity due to field inhomogeneity, and time dependence. A detailed overview is presented of the standard approaches to one of the main problems namely the determination of the residence times of charged particles in an adiabatic magnetic trap which involves nonadiabaticity in a crucial way. In a major departure from the standard approach, a new paradigm described here as 'macroquantum dynamics' was advanced by the author to address the problem of residence times. The evolution and development of this new paradigm is next presented as the main focus of the review. This consists of a probability amplitude Schroedinger-like formalism for the classical macrodomain, which has been shown to be a description of the system in the correspondence limit of large Landau quantum numbers. It is demonstrated that this represents a remarkable persistence of matter wave behaviour well into the classical macrodomain, leading to unexpected experimental consequences. Experimental results confirming some of the spectacular predictions of this formalism are presented. These refer to the existence of macroscopic matter wave interference phenomena and the observation of the curl-free vector potential a la Aharonov-Bohm in the macrodomain. The problem of the nonadiabatic leakage of particles from an adiabatic trap takes the appearance here of the quantum-like tunneling of the adiabatic potential. The multiplicity of residence times predicted by the set of Schroedinger-like equations have been well confirmed by experiments. A critical comparison is finally presented of the classical vs. macroquantum description of the system in the macrodomain. The new paradigm thus represents an entirely new and unexpected manifestation of quantum dynamics in the classical macrodomain

  6. Childhood Traumatic Experiences, Dissociative Symptoms, and Dissociative Disorder Comorbidity Among Patients With Panic Disorder: A Preliminary Study.

    Science.gov (United States)

    Ural, Cenk; Belli, Hasan; Akbudak, Mahir; Tabo, Abdulkadir

    2015-01-01

    This study assessed childhood trauma history, dissociative symptoms, and dissociative disorder comorbidity in patients with panic disorder (PD). A total of 92 psychotropic drug-naive patients with PD, recruited from outpatient clinics in the psychiatry department of a Turkish hospital, were involved in the study. Participants were assessed using the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D), Dissociation Questionnaire, Panic and Agoraphobia Scale, Panic Disorder Severity Scale, and Childhood Trauma Questionnaire. Of the patients with PD, 18 (19%) had a comorbid dissociative disorder diagnosis on screening with the SCID-D. The most prevalent disorders were dissociative disorder not otherwise specified, dissociative amnesia, and depersonalization disorders. Patients with a high degree of dissociation symptoms and dissociative disorder comorbidity had more severe PD than those without (p dissociation and PD. Among all of the subscales, the strongest relationship was with childhood emotional abuse. Logistic regression analysis showed that emotional abuse and severity of PD were independently associated with dissociative disorder. In our study, a significant proportion of the patients with PD had concurrent diagnoses of dissociative disorder. We conclude that the predominance of PD symptoms at admission should not lead the clinician to overlook the underlying dissociative process and associated traumatic experiences among these patients.

  7. Dissociative symptoms and dissociative disorders comorbidity in obsessive compulsive disorder: Symptom screening, diagnostic tools and reflections on treatment

    OpenAIRE

    Belli, Hasan

    2014-01-01

    Borderline personality disorder, conversion disorder and obsessive compulsive disorder frequently have dissociative symptoms. The literature has demonstrated that the level of dissociation might be correlated with the severity of obsessive compulsive disorder (OCD) and that those not responding to treatment had high dissociative symptoms. The structured clinical interview for DSM-IV dissociative disorders, dissociation questionnaire, somatoform dissociation questionnaire and dissociative expe...

  8. [Dissociative disorders and affective disorders].

    Science.gov (United States)

    Montant, J; Adida, M; Belzeaux, R; Cermolacce, M; Pringuey, D; Da Fonseca, D; Azorin, J-M

    2014-12-01

    The phenomenology of dissociative disorders may be complex and sometimes confusing. We describe here two cases who were initially misdiagnosed. The first case concerned a 61 year-old woman, who was initially diagnosed as an isolated dissociative fugue and was actually suffering from severe major depressive episode. The second case concerned a 55 year-old man, who was suffering from type I bipolar disorder and polyvascular disease, and was initially diagnosed as dissociative fugue in a mooddestabilization context, while it was finally a stroke. Yet dissociative disorders as affective disorder comorbidity are relatively unknown. We made a review on this topic. Dissociative disorders are often studied through psycho-trauma issues. Litterature is rare on affective illness comorbid with dissociative disorders, but highlight the link between bipolar and dissociative disorders. The later comorbidity often refers to an early onset subtype with also comorbid panic and depersonalization-derealization disorder. Besides, unipolar patients suffering from dissociative symptoms have more often cyclothymic affective temperament. Despite the limits of such studies dissociative symptoms-BD association seems to correspond to a clinical reality and further works on this topic may be warranted. Copyright © 2014 L’Encéphale. Published by Elsevier Masson SAS.. All rights reserved.

  9. On the fly quantum dynamics of electronic and nuclear wave packets

    Science.gov (United States)

    Komarova, Ksenia G.; Remacle, F.; Levine, R. D.

    2018-05-01

    Multielectronic states quantum dynamics on a grid is described in a manner motivated by on the fly classical trajectory computations. Non stationary electronic states are prepared by a few cycle laser pulse. The nuclei respond and begin moving. We solve the time dependent Schrödinger equation for the electronic and nuclear dynamics for excitation from the ground electronic state. A satisfactory accuracy is possible using a localized description on a discrete grid. This enables computing on the fly for both the nuclear and electronic dynamics including non-adiabatic couplings. Attosecond dynamics in LiH is used as an example.

  10. On the Magnitude of the Nonadiabatic Error for Highly Coupled Radicals

    Science.gov (United States)

    Stanton, J. F.

    2009-06-01

    A review is given of recent advances in the construction of (quasi)diabatic model Hamiltonians and their application to analyzing the spectroscopy of molecules with strong vibronic coupling. A numerical application to the vibronic levels of the BNB radical below 0.6 eV is presented, together with corresponding adiabatic (quantum chemistry) calculations. The agreement with the experimental levels is nearly quantitative with the model Hamiltonian, attesting to the power of the approach. On the contrary, it is also revealed that the magnitude of the nonadiabatic contributions to the zero-point energy and the lowest fundamental frequency of the coupling mode are considerably larger than expected, at least by your narrator.

  11. The co-occurrence of PTSD and dissociation: differentiating severe PTSD from dissociative-PTSD

    DEFF Research Database (Denmark)

    Armour, C.; Karstoft, K. I.; Richardson, J. D.

    2014-01-01

    A dissociative-posttraumatic stress disorder (PTSD) subtype has been included in the DSM-5. However, it is not yet clear whether certain socio-demographic characteristics or psychological/clinical constructs such as comorbid psychopathology differentiate between severe PTSD and dissociative-PTSD....... The current study investigated the existence of a dissociative-PTSD subtype and explored whether a number of trauma and clinical covariates could differentiate between severe PTSD alone and dissociative-PTSD. The current study utilized a sample of 432 treatment seeking Canadian military veterans. Participants...... were assessed with the Clinician Administered PTSD Scale (CAPS) and self-report measures of traumatic life events, depression, and anxiety. CAPS severity scores were created reflecting the sum of the frequency and intensity items from each of the 17 PTSD and 3 dissociation items. The CAPS severity...

  12. A genetically-encoded chloride and pH sensor for dissociating ion dynamics in the nervous system.

    Science.gov (United States)

    Raimondo, Joseph V; Joyce, Bradley; Kay, Louise; Schlagheck, Theresa; Newey, Sarah E; Srinivas, Shankar; Akerman, Colin J

    2013-01-01

    Within the nervous system, intracellular Cl(-) and pH regulate fundamental processes including cell proliferation, metabolism, synaptic transmission, and network excitability. Cl(-) and pH are often co-regulated, and network activity results in the movement of both Cl(-) and H(+). Tools to accurately measure these ions are crucial for understanding their role under physiological and pathological conditions. Although genetically-encoded Cl(-) and pH sensors have been described previously, these either lack ion specificity or are unsuitable for neuronal use. Here we present ClopHensorN-a new genetically-encoded ratiometric Cl(-) and pH sensor that is optimized for the nervous system. We demonstrate the ability of ClopHensorN to dissociate and simultaneously quantify Cl(-) and H(+) concentrations under a variety of conditions. In addition, we establish the sensor's utility by characterizing activity-dependent ion dynamics in hippocampal neurons.

  13. Dissociation and Memory Fragmentation in Posttraumatic Stress Disorder: An Evaluation of the Dissociative Encoding Hypothesis

    Science.gov (United States)

    Bedard-Gilligan, Michele; Zoellner, Lori A.

    2012-01-01

    Several prominent theories of posttraumatic stress disorder (PTSD) posit that peritraumatic dissociation results in insufficient encoding of the trauma memory and that persistent dissociation prevents memory elaboration, resulting in memory fragmentation and PTSD. In this review, we summarize the empirical literature on peritraumatic and trait dissociation and trauma narrative fragmentation as measured by meta-memory and rater/objective coding. Across 16 studies to date, the association between dissociation and fragmentation was most prominent when examining peritraumatic dissociation and patient's own ratings of memory fragmentation. This relationship did not hold when examining trait dissociation or rater-coded or computer-generated measures of fragmentation. Thus, initial evidence points more toward a strong self-reported association between constructs that is not supported on more objective fragmentation coding. Measurement overlap, construct ambiguity, and exclusion of potential confounds may underlie lack of a strong association between dissociation and objective-rated fragmentation. PMID:22348400

  14. [Screening for major dissociative disorders with the FDS, the German version of the Dissociative Experience Scale].

    Science.gov (United States)

    Rodewald, Frauke; Gast, Ursula; Emrich, Hinderk M

    2006-06-01

    The prevalence of major dissociative disorders (dissociative identity disorder, DID and similar forms of dissociative disorder not otherwise specified, DDNOS) in clinical samples is about 5 %. Despite their frequency, major dissociative disorders are often overseen for a long time. Screening-scales have proved to be effective to support clinical diagnosis. The aim of this study was to test, whether the Fragebogen für dissoziative Symptome (FDS), the German version of the Dissociative Experiences Scale (DES), differentiates between patients with dissociative disorders, non-dissociative disorders and non-clinical controls. Additionally, an optimal FDS-cutoff for a more detailed differential-diagnostic evaluation of the dissociative symptomatology should be identified. 150 participants with DID (group DID: n = 44), DDNOS (DDNOS: n = 22), posttraumatic disorders (TRAUMA: n = 20), other non-dissociative disorders (non-TRAUMA: n = 34) and non-clinical controls (KG: n = 30) completed the FDS. In the five diagnostic groups, mean values were calculated and compared for the FDS, DES and FDS-20. Via receiver-operating-curves the cutoff-scores, which differentiated best between participants with and without major dissociative disorders, were identified. FDS, DES and FDS-20 differentiate significantly between patients with and without major dissociative disorders. For all scales, there were significant differences between the diagnostic groups, with mean-scores decreasing continuously from the groups DID to DDNOS and TRAUMA. Between the groups non-TRAUMA and KG tendencies were found in the predicted direction. The optimal cutoff-scores to differentiate between participants with and without major dissociative disorders were 13 (FDS/FDS-20) and 15 (DES). Using these cutoff-scores, at least 90 % of the patients with major dissociative disorders could be identified correctly (sensitivity). The specifity of the scales was 0.89 to 0.90. Screening for major dissociative disorders

  15. Does phasic trauma treatment make patients with dissociative identity disorder treatment more dissociative?

    Science.gov (United States)

    Brand, Bethany; Loewenstein, Richard J

    2014-01-01

    Proponents of the iatrogenic model of the etiology of dissociative identity disorder (DID) have expressed concern that treatment focused on direct engagement and interaction with dissociated self-states harms DID patients. However, empirical data have shown that this type of DID treatment is beneficial. Analyzing data from the prospective Treatment of Patients With Dissociative Disorders (TOP DD) Study, we test empirically whether DID treatment is associated with clinically adverse manifestations of dissociated self-states: acting so differently that one feels like different people, hearing voices, and dissociative amnesia. We show that, over the course of the study, there were significant decreases in feeling like different people and hearing voices. These results indicate that this form of DID treatment does not lead to symptomatic worsening in these dimensions, as predicted by the iatrogenic model. Indeed, treatment provided by TOP DD therapists reduced, rather than increased, the extent to which patients experienced manifestations of pathological dissociation. Because severe symptomatology and impairment are associated with DID, iatrogenic harm may come from depriving DID patients of treatment that targets DID symptomatology.

  16. The dissociation mechanism and thermodynamic properties of HCl(aq) in hydrothermal fluids (to 700 °C, 60 kbar) by ab initio molecular dynamics simulations

    Science.gov (United States)

    Mei, Yuan; Liu, Weihua; Brugger, Joël; Sherman, David M.; Gale, Julian D.

    2018-04-01

    HCl is one of the most significant volatiles in the Earth's crust. It is well established that chloride activity and acidity (pH) play important roles in controlling the solubility of metals in aqueous hydrothermal fluids. Thus, quantifying the dissociation of HCl in aqueous solutions over a wide range of temperature and pressure is crucial for the understanding and numerical modeling of element mobility in hydrothermal fluids. Here we have conducted ab initio molecular dynamics (MD) simulations to investigate the mechanism of HCl(aq) dissociation and to calculate the thermodynamic properties for the dissociation reaction at 25-700 °C, 1 bar to 60 kbar, i.e. including high temperature and pressure conditions that are geologically important, but difficult to investigate via experiments. Our results predict that HCl(aq) tends to associate with increasing temperature, and dissociate with increasing pressure. In particular, HCl(aq) is highly dissociated at extremely high pressures, even at high temperatures (e.g., 60 kbar, 600-700 °C). At 25 °C, the calculated logKd values (6.79 ± 0.81) are close to the value (7.0) recommended by IUPAC (International Union of Pure and Applied Chemistry) and some previous experimental and theoretical studies (Simonson et al.., 1990; Sulpizi and Sprik, 2008, 2010). The MD simulations indicate full dissociation of HCl at low temperature; in contrast, some experiments were interpreted assuming significant association at high HCl concentrations (≥1 m HCltot) even at room T (logKd ∼0.7; e.g., Ruaya and Seward, 1987; Sretenskaya, 1992; review in Tagirov et al., 1997). This discrepancy is most likely the result of difficulties in the experimental determination of minor (if any) concentration of associated HCl(aq) under ambient conditions, and thus reflects differences in the activity models used for the interpretation of the experiments. With increasing temperature, the discrepancy between our MD results and previous experimental

  17. Observing electron localization in a dissociating H2+ molecule in real time.

    Science.gov (United States)

    Xu, H; Li, Zhichao; He, Feng; Wang, X; Atia-Tul-Noor, A; Kielpinski, D; Sang, R T; Litvinyuk, I V

    2017-06-16

    Dissociation of diatomic molecules with odd number of electrons always causes the unpaired electron to localize on one of the two resulting atomic fragments. In the simplest diatomic molecule H 2 + dissociation yields a hydrogen atom and a proton with the sole electron ending up on one of the two nuclei. That is equivalent to breaking of a chemical bond-the most fundamental chemical process. Here we observe such electron localization in real time by performing a pump-probe experiment. We demonstrate that in H 2 + electron localization is complete in just 15 fs when the molecule's internuclear distance reaches 8 atomic units. The measurement is supported by a theoretical simulation based on numerical solution of the time-dependent Schrödinger equation. This observation advances our understanding of detailed dynamics of molecular dissociation.

  18. Strong-Field Modulated Diffraction Effects in the Correlated Electron-Nuclear Motion in Dissociating H2+

    International Nuclear Information System (INIS)

    He Feng; Becker, Andreas; Thumm, Uwe

    2008-01-01

    We show that the electronic dynamics in a molecule driven by a strong field is complex and potentially even counterintuitive. As a prototype example, we simulate the interaction of a dissociating H 2 + molecule with an intense infrared laser pulse. Depending on the laser intensity, the direction of the electron's motion between the two nuclei is found to follow or oppose the classical laser-electric force. We explain the sensitive dependence of the correlated electronic-nuclear motion in terms of the diffracting electronic momentum distribution of the dissociating two-center system. The distribution is dynamically modulated by the nuclear motion and periodically shifted in the oscillating infrared electric field

  19. DC slice ion imaging study of atomic orbital orientation and alignment in photodissociation

    Science.gov (United States)

    Lee, Suk Kyoung

    A complete study of atomic photofragment polarization has been achieved by using DC slice imaging, a recently developed approach directly providing the central slice of the full 3D product distribution without any mathematical transformation. In this dissertation, the quantum mechanical treatment adapted for the sliced images has been derived to extract the angular momentum polarization anisotropy parameters for any recoil speeds. The important photodissociation dynamics of small polyatomic molecules has been presented based on the thorough interpretation of the observed orientation and alignment. The first demonstration of DC slice imaging of orbital polarization was a study of the 193 nm photodissociation of ethylene sulfide, followed by detailed investigation in ozone and OCS. In ozone, the speed-dependent orientation was measured for O(1D2) atom produced from photodissociation in the 248--285 nm region. The results show negligible orbital orientation following dissociation by circularly polarized light but strong recoil speed-dependent orientation following photolysis by linearly polarized light at all wavelengths studied. The origin of this polarization is ascribed to nonadiabatic transitions at avoided crossings and at long range. The atomic orbital alignment and orientation, including the higher order moments (K = 3, 4), has been carried out for the photodissociation of OCS at 193 nm. The observed speed-dependent beta and polarization parameters of S(1D2) atom support the interpretation that there are two main dissociation processes: a simultaneous two-surface excitation and the initial single-surface excitation followed by the nonadiabatic crossing to the ground state. The angle- and speed-dependent density matrix can be constructed containing the higher order contributions for circularly-polarized dissociation light. It was shown in one case that the higher order contributions should not be overlooked for an accurate picture of the dissociation dynamics in

  20. Posterior α EEG Dynamics Dissociate Current from Future Goals in Working Memory-Guided Visual Search.

    Science.gov (United States)

    de Vries, Ingmar E J; van Driel, Joram; Olivers, Christian N L

    2017-02-08

    working memory. However, working memory not only serves current goals, but also future goals, with differential impact upon visual selection. Little is known about how the brain differentiates between current and future goals. Here we show, for the first time, that modulations of brain oscillations in the EEG α frequency band in posterior cortex can dissociate current from future search goals in working memory. Moreover, the dynamics of these oscillations uncover how we flexibly switch focus between memory representations. Together, we reveal how the brain assigns priority for selection. Copyright © 2017 de Vries et al.

  1. Three-body dissociations: The photodissociation of dimethyl sulfoxide at 193 nm

    Energy Technology Data Exchange (ETDEWEB)

    Blank, D.A.; North, S.W.; Stranges, D. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    When a molecule with two equivalent chemical bonds is excited above the threshold for dissociation of both bonds, how the rupture of the two bonds is temporally coupled becomes a salient question. Following absorption at 193 nm dimethyl sulfoxide (CH{sub 3}SOCH{sub 3}) contains enough energy to rupture both C-S bonds. This can happen in a stepwise (reaction 1) or concerted (reaction 2) fashion where the authors use rotation of the SOCH{sub 3} intermediate prior to dissociation to define a stepwise dissociation: (1) CH{sub 3}SOCH{sub 3} {r_arrow} 2CH{sub 3} + SO; (2a) CH{sub 3}SOCH{sub 3} {r_arrow} CH{sub 3} + SOCH{sub 3}; and (2b) SOCH{sub 3} {r_arrow} SO + CH{sub 3}. Recently, the dissociation of dimethyl sulfoxide following absorption at 193 nm was suggested to involve simultaneous cleavage of both C-S bonds on an excited electronic surface. This conclusion was inferred from laser induced fluorescence (LIF) and resonant multiphoton ionization (2+1 REMPI) measurements of the internal energy content in the CH{sub 3} and SO photoproducts and a near unity quantum yield measured for SO. Since this type of concerted three body dissociation is very interesting and a rather rare event in photodissociation dynamics, the authors chose to investigate this system using the technique of photofragment translational spectroscopy at beamline 9.0.2.1. The soft photoionization provided by the VUV undulator radiation allowed the authors to probe the SOCH{sub 3} intermediate which had not been previously observed and provided good evidence that the dissociation of dimethyl sulfoxide primarily proceeds via a two step dissociation, reaction 2.

  2. Is the dissociative adult suggestible? A test of the trauma and fantasy models of dissociation.

    Science.gov (United States)

    Kluemper, Nicole S; Dalenberg, Constance

    2014-01-01

    Psychologists have long assumed a connection between traumatic experience and psychological dissociation. This hypothesis is referred to as the trauma model of dissociation. In the past decade, a series of papers have been published that question this traditional causal link, proposing an alternative fantasy model of dissociation. In the present research, the relationship among dissociation, suggestibility, and fantasy proneness was examined. Suggestibility was measured through the Gudjonsson Scale of Interrogative Suggestibility (GSS) as well as an autobiographically based version of this measure based on the events of September 11, 2001. Consistent with prior research and with the trauma model, dissociation correlated positively with trauma severity (r = .32, p suggestibility measure. Although some participants did become quite emotional during the procedure, the risk/benefit ratio was perceived by almost all participants to be positive, with more reactive individuals evaluating the procedure more positively. The results consistently support the trauma model of dissociation and fail to support the fantasy model of dissociation.

  3. Neural dynamics of event segmentation in music: converging evidence for dissociable ventral and dorsal networks.

    Science.gov (United States)

    Sridharan, Devarajan; Levitin, Daniel J; Chafe, Chris H; Berger, Jonathan; Menon, Vinod

    2007-08-02

    The real world presents our sensory systems with a continuous stream of undifferentiated information. Segmentation of this stream at event boundaries is necessary for object identification and feature extraction. Here, we investigate the neural dynamics of event segmentation in entire musical symphonies under natural listening conditions. We isolated time-dependent sequences of brain responses in a 10 s window surrounding transitions between movements of symphonic works. A strikingly right-lateralized network of brain regions showed peak response during the movement transitions when, paradoxically, there was no physical stimulus. Model-dependent and model-free analysis techniques provided converging evidence for activity in two distinct functional networks at the movement transition: a ventral fronto-temporal network associated with detecting salient events, followed in time by a dorsal fronto-parietal network associated with maintaining attention and updating working memory. Our study provides direct experimental evidence for dissociable and causally linked ventral and dorsal networks during event segmentation of ecologically valid auditory stimuli.

  4. Nonlocal and Nonadiabatic Effects in the Charge-Density Response of Solids: A Time-Dependent Density-Functional Approach

    Science.gov (United States)

    Panholzer, Martin; Gatti, Matteo; Reining, Lucia

    2018-04-01

    The charge-density response of extended materials is usually dominated by the collective oscillation of electrons, the plasmons. Beyond this feature, however, intriguing many-body effects are observed. They cannot be described by one of the most widely used approaches for the calculation of dielectric functions, which is time-dependent density functional theory (TDDFT) in the adiabatic local density approximation (ALDA). Here, we propose an approximation to the TDDFT exchange-correlation kernel which is nonadiabatic and nonlocal. It is extracted from correlated calculations in the homogeneous electron gas, where we have tabulated it for a wide range of wave vectors and frequencies. A simple mean density approximation allows one to use it in inhomogeneous materials where the density varies on a scale of 1.6 rs or faster. This kernel contains effects that are completely absent in the ALDA; in particular, it correctly describes the double plasmon in the dynamic structure factor of sodium, and it shows the characteristic low-energy peak that appears in systems with low electronic density. It also leads to an overall quantitative improvement of spectra.

  5. Dissociation - a preliminary contextual model

    Directory of Open Access Journals (Sweden)

    C Krüger

    2007-02-01

    Full Text Available Background. The Diagnostic and Statistical Manual of Mental Disorders (DSM system has certain limitations when applied to two South African examples of dissociation, because it is descriptive (non-explanatory and focuses on intrapsychic (non-communal processes. Even the existing Western explanatory models of dissociation fail to accommodate fully the communal aspects of dissociation in our South African context. Objectives and methods. The aim was to explore an expanded perspective on dissociation that does not limit it to an intrapsychic phenomenon, but that accounts for the interrelatedness of individuals within their social context. Auto-ethnography was used. In this article a collective, socially orientated, contextual hermeneutic was applied to two local examples of dissociation. Three existing Western models were expanded along multicontextual, collective lines, for them to be more useful in the pluralistic South African context. Results. This preliminary contextual model of dissociation includes a person’s interpersonal, socio-cultural, and spiritual contexts, in addition to the intrapsychic context. Dissociation is considered to be a normal information-processing tool that maintains balanced, coherent selves-in-society, i.e. individuals connected to each other. In the South African context dissociation appears mostly as a normal phenomenon and seldom as a sign of mental illness. Dissociation is pivotal for the normal construction of individual and communal identities in the face of conflicting sets of information from various contexts. Dissociation may help individuals or communities to survive in a world of conflicting messages, where conflict is often interpersonal/cultural/societal in nature, rather than primarily intrapsychic. Conclusions. This model should be developed and evaluated further. Such evaluation would require suitable new local terminology.

  6. Global functioning and disability in dissociative disorders.

    Science.gov (United States)

    Mueller-Pfeiffer, Christoph; Rufibach, Kaspar; Perron, Noelle; Wyss, Daniela; Kuenzler, Cornelia; Prezewowsky, Cornelia; Pitman, Roger K; Rufer, Michael

    2012-12-30

    Dissociative disorders are frequent comorbid conditions of other mental disorders. Yet, there is controversy about their clinical relevance, and little systematic research has been done on how they influence global functioning. Outpatients and day care patients (N=160) of several psychiatric units in Switzerland were assessed with the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV Axis I Disorders, Structured Clinical Interview for DSM-IV Dissociative Disorders, Global Assessment of Functioning Scale, and World Health Organization Disability Assessment Schedule-II. The association between subjects with a dissociative disorder (N=30) and functional impairment after accounting for non-dissociative axis I disorders was evaluated by linear regression models. We found a proportion of 18.8% dissociative disorders (dissociative amnesia=0%, dissociative fugue=0.6%, depersonalization disorder=4.4%, dissociative identity disorder=7.5%, dissociative disorder-not-otherwise-specified=6.3%) across treatment settings. Adjusted for other axis I disorders, subjects with a comorbid dissociative identity disorder or dissociative disorder-not-otherwise-specified had a median global assessment of functioning score that was 0.86 and 0.88 times, respectively, the score of subjects without a comorbid dissociative disorder. These findings support the hypothesis that complex dissociative disorders, i.e., dissociative identity disorder and dissociative disorder-not-otherwise-specified, contribute to functional impairment above and beyond the impact of co-existing non-dissociative axis I disorders, and that they qualify as "serious mental illness". Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  7. Dissociative symptoms and dissociative disorders comorbidity in obsessive compulsive disorder: Symptom screening, diagnostic tools and reflections on treatment.

    Science.gov (United States)

    Belli, Hasan

    2014-08-16

    Borderline personality disorder, conversion disorder and obsessive compulsive disorder frequently have dissociative symptoms. The literature has demonstrated that the level of dissociation might be correlated with the severity of obsessive compulsive disorder (OCD) and that those not responding to treatment had high dissociative symptoms. The structured clinical interview for DSM-IV dissociative disorders, dissociation questionnaire, somatoform dissociation questionnaire and dissociative experiences scale can be used for screening dissociative symptoms and detecting dissociative disorders in patients with OCD. However, a history of neglect and abuse during childhood is linked to a risk factor in the pathogenesis of dissociative psychopathology in adults. The childhood trauma questionnaire-53 and childhood trauma questionnaire-40 can be used for this purpose. Clinicians should not fail to notice the hidden dissociative symptoms and childhood traumatic experiences in OCD cases with severe symptoms that are resistant to treatment. Symptom screening and diagnostic tools used for this purpose should be known. Knowing how to treat these pathologies in patients who are diagnosed with OCD can be crucial.

  8. The time-dependent density matrix renormalisation group method

    Science.gov (United States)

    Ma, Haibo; Luo, Zhen; Yao, Yao

    2018-04-01

    Substantial progress of the time-dependent density matrix renormalisation group (t-DMRG) method in the recent 15 years is reviewed in this paper. By integrating the time evolution with the sweep procedures in density matrix renormalisation group (DMRG), t-DMRG provides an efficient tool for real-time simulations of the quantum dynamics for one-dimensional (1D) or quasi-1D strongly correlated systems with a large number of degrees of freedom. In the illustrative applications, the t-DMRG approach is applied to investigate the nonadiabatic processes in realistic chemical systems, including exciton dissociation and triplet fission in polymers and molecular aggregates as well as internal conversion in pyrazine molecule.

  9. Surface Hopping Dynamics with Correlated Single-Reference Methods: 9H-Adenine as a Case Study

    Czech Academy of Sciences Publication Activity Database

    Plasser, F.; Crespo-Otero, R.; Pederzoli, Marek; Pittner, Jiří; Lischka, H.; Barbatti, M.

    2014-01-01

    Roč. 10, č. 4 (2014), s. 1395-1405 ISSN 1549-9618 R&D Projects: GA ČR(CZ) GAP208/12/0559 Institutional support: RVO:61388955 Keywords : density-functional theory * resolved photoelectron spectroscopy * nonadiabatic molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.498, year: 2014

  10. Hyperglycemia associated dissociative fugue (organic dissociative disorder) in an elderly.

    Science.gov (United States)

    Ram, Dushad; Ashoka, H G; Gowdappa, Basavnna

    2015-01-01

    Inadequate glycemic control in patients with diabetes is known to be associated with psychiatric disorders such as depression, anxiety disorder, and cognitive impairment. However, dissociative syndrome has not been reported so far. Here we are reporting a case of repeated dissociative fugue associated with hyperglycemia, in an elderly with type II diabetes. Possible neurobiological mechanism has been discussed.

  11. Hyperglycemia associated dissociative fugue (organic dissociative disorder) in an elderly

    OpenAIRE

    Ram, Dushad; Ashoka, H. G; Gowdappa, Basavnna

    2015-01-01

    Inadequate glycemic control in patients with diabetes is known to be associated with psychiatric disorders such as depression, anxiety disorder, and cognitive impairment. However, dissociative syndrome has not been reported so far. Here we are reporting a case of repeated dissociative fugue associated with hyperglycemia, in an elderly with type II diabetes. Possible neurobiological mechanism has been discussed.

  12. The Dual Role of Disorder on the Dissociation of Interfacial Charge Transfer Excitons

    Science.gov (United States)

    Shi, Liang; Lee, Chee-Kong; Willard, Adam

    In organic-based photovoltaics (OPV), dissociation of neutral photo-excitations (i.e., Frenkel excitons) into free charge carriers requires the excitons to overcome binding energy that can significantly exceed thermal energies. The inability of bound charges to overcome this large binding energy has been implicated as a primary source of efficiency loss in OPVs. Despite the potential impact on the performance of organic solar cells much remains to be understood about the microscopic mechanism of exciton dissociation in OPV materials. Here we explore the role of static molecular disorder in mediating this charge dissociation process. Using a simple lattice model of exciton dynamics we demonstrate that random spatial variations in the energetic landscape can mitigate the effects of the exciton binding energy by lowering the free energy barrier. By considering the competition between this thermodynamic effect and the disorder-induced slowing of dissociation kinetics we demonstrate that exciton dissociation yields are expected to depend non-monotonically on the degree of static disorder. We conclude that a certain amount of molecular-scale disorder is desirable in order to optimize the performance of organic photovoltaic materials.

  13. Steering dissociation of Br2 molecules with two femtosecond pulses via wave packet interference.

    Science.gov (United States)

    Han, Yong-Chang; Yuan, Kai-Jun; Hu, Wen-Hui; Yan, Tian-Min; Cong, Shu-Lin

    2008-04-07

    The dissociation dynamics of Br2 molecules induced by two femtosecond pump pulses are studied based on the calculation of time-dependent quantum wave packet. Perpendicular transition from X 1Sigma g+ to A 3Pi 1u+ and 1Pi 1u+ and parallel transition from X 1Sigma g+ to B 3Pi 0u+, involving two product channels Br (2P3/2)+Br (2P3/2) and Br (2P3/2)+Br* (2P1/2), respectively, are taken into account. Two pump pulses create dissociating wave packets interfering with each other. By varying laser parameters, the interference of dissociating wave packets can be controlled, and the dissociation probabilities of Br2 molecules on the three excited states can be changed to different degrees. The branching ratio of Br*/(Br+Br*) is calculated as a function of pulse delay time and phase difference.

  14. A genetically-encoded chloride and pH sensor for dissociating ion dynamics in the nervous system

    Science.gov (United States)

    Raimondo, Joseph V.; Joyce, Bradley; Kay, Louise; Schlagheck, Theresa; Newey, Sarah E.; Srinivas, Shankar; Akerman, Colin J.

    2013-01-01

    Within the nervous system, intracellular Cl− and pH regulate fundamental processes including cell proliferation, metabolism, synaptic transmission, and network excitability. Cl− and pH are often co-regulated, and network activity results in the movement of both Cl− and H+. Tools to accurately measure these ions are crucial for understanding their role under physiological and pathological conditions. Although genetically-encoded Cl− and pH sensors have been described previously, these either lack ion specificity or are unsuitable for neuronal use. Here we present ClopHensorN—a new genetically-encoded ratiometric Cl− and pH sensor that is optimized for the nervous system. We demonstrate the ability of ClopHensorN to dissociate and simultaneously quantify Cl− and H+ concentrations under a variety of conditions. In addition, we establish the sensor's utility by characterizing activity-dependent ion dynamics in hippocampal neurons. PMID:24312004

  15. A genetically-encoded chloride and pH sensor for dissociating ion dynamics in the nervous system

    Directory of Open Access Journals (Sweden)

    Joseph Valentino Raimondo

    2013-11-01

    Full Text Available Within the nervous system, intracellular Cl- and pH regulate fundamental processes including cell proliferation, metabolism, synaptic transmission and network excitability. Cl- and pH are often co-regulated, and network activity results in the movement of both Cl- and H+. Tools to accurately measure these ions are crucial for understanding their role under physiological and pathological conditions. Although genetically-encoded Cl- and pH sensors have been described previously, these either lack ion specificity or are unsuitable for neuronal use. Here we present ClopHensorN - a new genetically-encoded ratiometric Cl- and pH sensor that is optimized for the nervous system. We demonstrate the ability of ClopHensorN to dissociate and simultaneously quantify Cl- and H+ concentrations under a variety of conditions. In addition, we establish the sensor’s utility by characterizing activity-dependent ion dynamics in hippocampal neurons.

  16. Dissociation and memory fragmentation in post-traumatic stress disorder: an evaluation of the dissociative encoding hypothesis.

    Science.gov (United States)

    Bedard-Gilligan, Michele; Zoellner, Lori A

    2012-01-01

    Several prominent theories of post-traumatic stress disorder (PTSD) posit that peritraumatic dissociation results in insufficient encoding of the trauma memory and that persistent dissociation prevents memory elaboration, resulting in memory fragmentation and PTSD. In this review we summarise the empirical literature on peritraumatic and trait dissociation and trauma narrative fragmentation as measured by meta-memory and rater/objective coding. Across 16 studies to date, the association between dissociation and fragmentation was most prominent when examining peritraumatic dissociation and patient's own ratings of memory fragmentation. This relationship did not hold when examining trait dissociation or rater-coded or computer-generated measures of fragmentation. Thus initial evidence points more towards a strong self-reported association between constructs that is not supported on more objective fragmentation coding. Measurement overlap, construct ambiguity, and exclusion of potential confounds may underlie lack of a strong association between dissociation and objective-rated fragmentation.

  17. Study of DNA Origami Dimerization and Dimer Dissociation Dynamics and of the Factors that Limit Dimerization.

    Science.gov (United States)

    Liber, Miran; Tomov, Toma E; Tsukanov, Roman; Berger, Yaron; Popov, Mary; Khara, Dinesh C; Nir, Eyal

    2018-06-01

    Organizing DNA origami building blocks into higher order structures is essential for fabrication of large structurally and functionally diverse devices and molecular machines. Unfortunately, the yields of origami building block attachment reactions are typically not sufficient to allow programed assembly of DNA devices made from more than a few origami building blocks. To investigate possible reasons for these low yields, a detailed single-molecule fluorescence study of the dynamics of rectangular origami dimerization and origami dimer dissociation reactions is conducted. Reactions kinetics and yields are investigated at different origami and ion concentrations, for different ion types, for different lengths of bridging strands, and for the "sticky end" and "weaving welding" attachment techniques. Dimerization yields are never higher than 86%, which is typical for such systems. Analysis of the dynamic data shows that the low yield cannot be explained by thermodynamic instability or structural imperfections of the origami constructs. Atomic force microscopy and gel electrophoresis evidence reveal self-dimerization of the origami monomers, likely via blunt-end interactions made possible by the presence of bridging strands. It is suggested that this mechanism is the major factor that inhibits correct dimerization and means to overcome it are discussed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Dissociative chemisorption of N2 on Rhenium: Dynamics at high impact energies

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm; Billing, Gert D.; Hansen, Flemming Yssing

    1990-01-01

    forcing model. It is found that the energy transfer from the molecule to the phonons of the crystal is very significant. The smaller than unity dissociative sticking probability found experimentally even at the highest impact energies well above the barrier energy can be accounted for by the Landau...

  19. Hyperglycemia associated dissociative fugue (organic dissociative disorder in an elderly

    Directory of Open Access Journals (Sweden)

    Dushad Ram

    2015-01-01

    Full Text Available Inadequate glycemic control in patients with diabetes is known to be associated with psychiatric disorders such as depression, anxiety disorder, and cognitive impairment. However, dissociative syndrome has not been reported so far. Here we are reporting a case of repeated dissociative fugue associated with hyperglycemia, in an elderly with type II diabetes. Possible neurobiological mechanism has been discussed.

  20. Dissociative disorders in DSM-5.

    Science.gov (United States)

    Spiegel, David; Lewis-Fernández, Roberto; Lanius, Ruth; Vermetten, Eric; Simeon, Daphne; Friedman, Matthew

    2013-01-01

    The rationale, research literature, and proposed changes to the dissociative disorders and conversion disorder in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) are presented. Dissociative identity disorder will include reference to possession as well as identity fragmentation, to make the disorder more applicable to culturally diverse situations. Dissociative amnesia will include dissociative fugue as a subtype, since fugue is a rare disorder that always involves amnesia but does not always include confused wandering or loss of personality identity. Depersonalization disorder will include derealization as well, since the two often co-occur. A dissociative subtype of posttraumatic stress disorder (PTSD), defined by the presence of depersonalization or derealization in addition to other PTSD symptoms, is being recommended, based upon new epidemiological and neuroimaging evidence linking it to an early life history of adversity and a combination of frontal activation and limbic inhibition. Conversion disorder (functional neurological symptom disorder) will likely remain with the somatic symptom disorders, despite considerable dissociative comorbidity.

  1. Rabi oscillations in the dissociative continuum: Rotation and alignment effects

    Science.gov (United States)

    Granucci, Giovanni; Magnier, Sylvie; Persico, Maurizio

    2002-01-01

    We have simulated a set of experiments in which Rabi oscillations are induced in bound-free and free-free transitions of a diatomic molecule. Dissociative vibrational states belonging to different electronic terms are involved. We show analytically and confirm computationally that a simple relationship exists between the one-dimensional dynamics of a molecule with fixed orientation with respect to the polarization of the radiation field and the three-dimensional dynamics of a rotating system. It is demonstrated that sufficiently short laser pulses can induce oscillations in the probabilities of two coupled electronic states, and in the yields of the respective dissociation products, as functions of the radiation intensity. As a result of molecular rotation the oscillations are damped but not washed out. The initial thermal distribution on several rotational levels has a negligible effect on the photodissociation yields and other experimentally relevant quantities. Since the molecule undergoes a strong alignment along the polarization axis of the laser field, the ejection of atoms and ions is anisotropic. We have chosen the well known diatomic ion Na2+ as a convenient example.

  2. Nonadiabatic theory of strong-field atomic effects under elliptical polarization

    International Nuclear Information System (INIS)

    Wang Xu; Eberly, J. H.

    2012-01-01

    Elliptically polarized laser fields provide a new channel for access to strong-field processes that are either suppressed or not present under linear polarization. Quantum theory is mostly unavailable for their analysis, and we report here results of a systematic study based on a classical ensemble theory with solution of the relevant ab inito time-dependent Newton equations for selected model atoms. The study's approach is necessarily nonadiabatic, as it follows individual electron trajectories leading to single, double, and triple ionizations. Of particular interest are new results bearing on open questions concerning experimental reports of unexplained species dependences as well as double-electron release times that are badly matched by a conventional adiabatic quantum tunneling theory. We also report the first analysis of electron trajectories for sequential and non-sequential triple ionization.

  3. Nonadiabatic quantum state control of many bosons in few wells

    DEFF Research Database (Denmark)

    Tichy, Malte C.; Kock Pedersen, Mads; Mølmer, Klaus

    2013-01-01

    We present a fast scheme for arbitrary unitary control of interacting bosonic atoms in a double well. Assuming fixed interwell tunneling rate and intrawell interaction strength, we control the many-atom state by a discrete sequence of shifts of the single-well energies. For strong interactions......, resonant tunneling transitions implement beam-splitter U(2) rotations among atom number eigenstates, which can be combined and, thus, permit full controllability. By numerically optimizing such sequences of couplings at avoided level crossings, we extend the realm of full controllability to a wide range...... of realistic interaction parameters, while we remain in the simple control space. We demonstrate the efficiency and the high achievable fidelity of our proposal with nonadiabatic population transfer, NOON-state creation, a cnot gate, and a transistorlike, conditional evolution of several atoms....

  4. Dissociation dynamics of anionic and excited neutral fragments of gaseous SiCl4 following Cl 2p and Si 2p core-level excitations

    International Nuclear Information System (INIS)

    Chen, J M; Lu, K T; Lee, J M; Chou, T L; Chen, H C; Chen, S A; Haw, S C; Chen, T H

    2008-01-01

    The state-selective dissociation dynamics for anionic and excited neutral fragments of gaseous SiCl 4 following Cl 2p and Si 2p core-level excitations were characterized by combining measurements of the photon-induced anionic dissociation, x-ray absorption and UV/visible dispersed fluorescence. The transitions of core electrons to high Rydberg states/doubly excited states in the vicinity of both Si 2p and Cl 2p ionization thresholds of gaseous SiCl 4 lead to a remarkably enhanced production of anionic, Si - and Cl - , fragments and excited neutral atomic, Si*, fragments. This enhancement via core-level excitation near the ionization threshold of gaseous SiCl 4 is explained in terms of the contributions from the Auger decay of doubly excited states, shake-modified resonant Auger decay, or/and post-collision interaction. These complementary results provide insight into the state-selective anionic and excited neutral fragmentation of gaseous molecules via core-level excitation.

  5. Catalytic methanol dissociation

    International Nuclear Information System (INIS)

    Alcinikov, Y.; Fainberg, V.; Garbar, A.; Gutman, M.; Hetsroni, G.; Shindler, Y.; Tatrtakovsky, L.; Zvirin, Y.

    1998-01-01

    Results of the methanol dissociation study on copper/potassium catalyst with alumina support at various temperatures are presented. The following gaseous and liquid products at. The catalytic methanol dissociation is obtained: hydrogen, carbon monoxide, carbon dioxide, methane, and dimethyl ether. Formation rates of these products are discussed. Activation energies of corresponding reactions are calculated

  6. Charge and energy dynamics in photo-excited poly(para-phenylenevinylene) systems

    International Nuclear Information System (INIS)

    Gisslen, L.; Johansson, A.; Stafstroem, S.

    2004-01-01

    We report results from simulations of charge and energy dynamics in poly(para-phenylenevinylene) (PPV) and PPV interacting with C 60 . The simulations were performed by solving the time-dependent Schroedinger equation and the lattice equation of motion simultaneously and nonadiabatically. The electronic system and the coupling of the electrons to the lattice were described by an extended three-dimensional version of the Su-Schrieffer-Heeger model, which also included an external electric field. Electron and lattice dynamics following electronic excitations at different energies have been simulated. The effect of additional lattice energy was also included in the simulations. Our results show that both exciton diffusion and transitions from high to lower lying excitations are stimulated by increasing the lattice energy. Also field induced charge separation occurs faster if the lattice energy is increased. This separation process is highly nonadiabatic and involves a significant rearrangement of the electron distribution. In the case of PPV coupled to C 60 , we observe a spontaneous charge separation. The separation time is in this case limited by the local concentration of C 60 molecules close to the PPV chain

  7. Dissociative symptoms and neuroendocrine dysregulation in depression.

    Science.gov (United States)

    Bob, Petr; Fedor-Freybergh, Peter; Jasova, Denisa; Bizik, Gustav; Susta, Marek; Pavlat, Josef; Zima, Tomas; Benakova, Hana; Raboch, Jiri

    2008-10-01

    Dissociative symptoms are traditionally attributed to psychological stressors that produce dissociated memories related to stressful life events. Dissociative disorders and dissociative symptoms including psychogenic amnesia, fugue, dissociative identity-disorder, depersonalization, derealization and other symptoms or syndromes have been reported as an epidemic psychiatric condition that may be coexistent with various psychiatric diagnoses such as depression, schizophrenia, borderline personality disorder or anxiety disorders. According to recent findings also the somatic components of dissociation may occur and influence brain, autonomic and neuroendocrine functions. At this time there are only few studies examining neuroendocrine response related to dissociative symptoms that suggest significant dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis. The aim of the present study is to perform examination of HPA axis functioning indexed by basal cortisol and prolactin and test their relationship to psychic and somatoform dissociative symptoms. Basal cortisol and prolactin and psychic and somatoform dissociative symptoms were assessed in 40 consecutive inpatients with diagnosis of unipolar depression mean age 43.37 (SD=12.21). The results show that prolactin and cortisol as indices of HPA axis functioning manifest significant relationship to dissociative symptoms. Main results represent highly significant correlations obtained by simple regression between psychic dissociative symptoms (DES) and serum prolactin (R=0.55, p=0.00027), and between somatoform dissociation (SDQ-20) and serum cortisol (R=-0.38, p=0.015). These results indicate relationship between HPA-axis reactivity and dissociative symptoms in unipolar depressive patients that could reflect passive coping behavior and disengagement.

  8. Dissociative symptomatology in cancer patients

    Science.gov (United States)

    Civilotti, Cristina; Castelli, Lorys; Binaschi, Luca; Cussino, Martina; Tesio, Valentina; Di Fini, Giulia; Veglia, Fabio; Torta, Riccardo

    2015-01-01

    Introduction: The utilization of the post-traumatic stress disorder (PTSD) diagnostic spectrum is currently being debated to categorize psychological adjustment in cancer patients. The aims of this study were to: (1) evaluate the presence of cancer-related traumatic dissociative symptomatology in a sample of cancer patients; (2) examine the correlation of cancer-related dissociation and sociodemographic and medical variables, anxiety, depression, and post-traumatic stress symptomatology; (3) investigate the predictors of cancer-related dissociation. Methods: Ninety-two mixed cancer patients (mean age: 58.94, ds = 10.13) recruited from two hospitals in northern Italy were administered a questionnaire on sociodemographic and medical characteristics, the Karnofsky Scale to measure the level of patient activity and medical care requirements, the Hospital Anxiety and Depression Scale (HADS) to evaluate the presence of anxiety and depression, the Impact of Event Scale Revised (IES-R) to assess the severity of intrusion, avoidance, and hypervigilance, and the Peritraumatic Dissociative Experiences Questionnaire (PDEQ) to quantify the traumatic dissociative symptomatology. Results: 31.5% of participants report a PDEQ score above the cutoff. The results indicated that dissociative symptomatology was positively correlated with HADS scores (HADS-Anxiety: r = 0.476, p dissociative symptomatology. The results converged on a three predictor model revealing that IES-R-Intrusion, IES-R-Avoidance, and IES-R-Hyperarousal accounted for 53.9% of the explained variance. Conclusion: These findings allow us to hypothesize a specific psychological reaction which may be ascribed to the traumatic spectrum within the context of cancer, emphasizing the close relationship between the origin of dissociative constituents which, according to the scientific literature, compose the traumatic experience. Our results have implications for understanding dissociative symptomatology in a cancer

  9. An exploration of the influence of diagonal dissociation and moderate changes in speed on locomotor parameters in trotting horses

    Directory of Open Access Journals (Sweden)

    Sarah Jane Hobbs

    2016-06-01

    Full Text Available Background. Although the trot is described as a diagonal gait, contacts of the diagonal pairs of hooves are not usually perfectly synchronized. Although subtle, the timing dissociation between contacts of each diagonal pair could have consequences on gait dynamics and provide insight into the functional strategies employed. This study explores the mechanical effects of different diagonal dissociation patterns when speed was matched between individuals and how these effects link to moderate, natural changes in trotting speed. We anticipate that hind-first diagonal dissociation at contact increases with speed, diagonal dissociation at contact can reduce collision-based energy losses and predominant dissociation patterns will be evident within individuals. Methods. The study was performed in two parts: in the first 17 horses performed speed-matched trotting trials and in the second, five horses each performed 10 trotting trials that represented a range of individually preferred speeds. Standard motion capture provided kinematic data that were synchronized with ground reaction force (GRF data from a series of force plates. The data were analyzed further to determine temporal, speed, GRF, postural, mass distribution, moment, and collision dynamics parameters. Results. Fore-first, synchronous, and hind-first dissociations were found in horses trotting at (3.3 m/s ± 10%. In these speed-matched trials, mean centre of pressure (COP cranio-caudal location differed significantly between the three dissociation categories. The COP moved systematically and significantly (P = .001 from being more caudally located in hind-first dissociation (mean location = 0.41 ± 0.04 through synchronous (0.36 ± 0.02 to a more cranial location in fore-first dissociation (0.32 ± 0.02. Dissociation patterns were found to influence function, posture, and balance parameters. Over a moderate speed range, peak vertical forelimb GRF had a strong relationship with dissociation

  10. Experimentally-induced dissociation impairs visual memory.

    Science.gov (United States)

    Brewin, Chris R; Mersaditabari, Niloufar

    2013-12-01

    Dissociation is a phenomenon common in a number of psychological disorders and has been frequently suggested to impair memory for traumatic events. In this study we explored the effects of dissociation on visual memory. A dissociative state was induced experimentally using a mirror-gazing task and its short-term effects on memory performance were investigated. Sixty healthy individuals took part in the experiment. Induced dissociation impaired visual memory performance relative to a control condition; however, the degree of dissociation was not associated with lower memory scores in the experimental group. The results have theoretical and practical implications for individuals who experience frequent dissociative states such as patients with posttraumatic stress disorder (PTSD). Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Non-equilibrium dynamics in disordered materials: Ab initio molecular dynamics simulations

    International Nuclear Information System (INIS)

    Ohmura, Satoshi; Nagaya, Kiyonobu; Yao, Makoto; Shimojo, Fuyuki

    2015-01-01

    The dynamic properties of liquid B 2 O 3 under pressure and highly-charged bromophenol molecule are studied by using molecular dynamics (MD) simulations based on density functional theory (DFT). Diffusion properties of covalent liquids under high pressure are very interesting in the sense that they show unexpected pressure dependence. It is found from our simulation that the magnitude relation of diffusion coefficients for boron and oxygen in liquid B 2 O 3 shows the anomalous pressure dependence. The simulation clarified the microscopic origin of the anomalous diffusion properties. Our simulation also reveals the dissociation mechanism in the coulomb explosion of the highly-charged bromophenol molecule. When the charge state n is 6, hydrogen atom in the hydroxyl group dissociates at times shorter than 20 fs while all hydrogen atoms dissociate when n is 8. After the hydrogen dissociation, the carbon ring breaks at about 100 fs. There is also a difference on the mechanism of the ring breaking depending on charge states, in which the ring breaks with expanding (n = 6) or shrink (n = 8)

  12. Speech-Language Dissociations, Distractibility, and Childhood Stuttering

    Science.gov (United States)

    Conture, Edward G.; Walden, Tedra A.; Lambert, Warren E.

    2015-01-01

    Purpose This study investigated the relation among speech-language dissociations, attentional distractibility, and childhood stuttering. Method Participants were 82 preschool-age children who stutter (CWS) and 120 who do not stutter (CWNS). Correlation-based statistics (Bates, Appelbaum, Salcedo, Saygin, & Pizzamiglio, 2003) identified dissociations across 5 norm-based speech-language subtests. The Behavioral Style Questionnaire Distractibility subscale measured attentional distractibility. Analyses addressed (a) between-groups differences in the number of children exhibiting speech-language dissociations; (b) between-groups distractibility differences; (c) the relation between distractibility and speech-language dissociations; and (d) whether interactions between distractibility and dissociations predicted the frequency of total, stuttered, and nonstuttered disfluencies. Results More preschool-age CWS exhibited speech-language dissociations compared with CWNS, and more boys exhibited dissociations compared with girls. In addition, male CWS were less distractible than female CWS and female CWNS. For CWS, but not CWNS, less distractibility (i.e., greater attention) was associated with more speech-language dissociations. Last, interactions between distractibility and dissociations did not predict speech disfluencies in CWS or CWNS. Conclusions The present findings suggest that for preschool-age CWS, attentional processes are associated with speech-language dissociations. Future investigations are warranted to better understand the directionality of effect of this association (e.g., inefficient attentional processes → speech-language dissociations vs. inefficient attentional processes ← speech-language dissociations). PMID:26126203

  13. Objective documentation of child abuse and dissociation in 12 murderers with dissociative identity disorder.

    Science.gov (United States)

    Lewis, D O; Yeager, C A; Swica, Y; Pincus, J H; Lewis, M

    1997-12-01

    The skepticism regarding the existence of dissociative identity disorder as well as the abuse that engenders it persists for lack of objective documentation. This is doubly so for the disorder in murderers because of issues of suspected malingering. This article presents objective verification of both dissociative symptoms and severe abuse during childhood in a series of adult murderers with dissociative identity disorder. This study consisted of a review of the clinical records of 11 men and one woman with DSM-IV-defined dissociative identity disorder who had committed murder. Data were gathered from medical, psychiatric, social service, school, military, and prison records and from records of interviews with subjects' family members and others. Handwriting samples were also examined. Data were analyzed qualitatively. Signs and symptoms of dissociative identity disorder in childhood and adulthood were corroborated independently and from several sources in all 12 cases; objective evidence of severe abuse was obtained in 11 cases. The subjects had amnesia for most of the abuse and underreported it. Marked changes in writing style and/or signatures were documented in 10 cases. This study establishes, once and for all, the linkage between early severe abuse and dissociative identity disorder. Further, the data demonstrate that the disorder can be distinguished from malingering and from other disorders. The study shows that it is possible, with great effort, to obtain objective evidence of both the symptoms of dissociative identity disorder and the abuse that engenders it.

  14. Nonadiabatic charged spherical evolution in the postquasistatic approximation

    International Nuclear Information System (INIS)

    Rosales, L.; Barreto, W.; Peralta, C.; Rodriguez-Mueller, B.

    2010-01-01

    We apply the postquasistatic approximation, an iterative method for the evolution of self-gravitating spheres of matter, to study the evolution of dissipative and electrically charged distributions in general relativity. The numerical implementation of our approach leads to a solver which is globally second-order convergent. We evolve nonadiabatic distributions assuming an equation of state that accounts for the anisotropy induced by the electric charge. Dissipation is described by streaming-out or diffusion approximations. We match the interior solution, in noncomoving coordinates, with the Vaidya-Reissner-Nordstroem exterior solution. Two models are considered: (i) a Schwarzschild-like shell in the diffusion limit; and (ii) a Schwarzschild-like interior in the free-streaming limit. These toy models tell us something about the nature of the dissipative and electrically charged collapse. Diffusion stabilizes the gravitational collapse producing a spherical shell whose contraction is halted in a short characteristic hydrodynamic time. The streaming-out radiation provides a more efficient mechanism for emission of energy, redistributing the electric charge on the whole sphere, while the distribution collapses indefinitely with a longer hydrodynamic time scale.

  15. Dissociative Part-Dependent Resting-State Activity in Dissociative Identity Disorder : A Controlled fMRI Perfusion Study

    NARCIS (Netherlands)

    Schlumpf, Yolanda R.; Reinders, Antje A. T. S.; Nijenhuis, Ellert R. S.; Luechinger, Roger; van Osch, Matthias J. P.; Jaencke, Lutz

    2014-01-01

    Background: In accordance with the Theory of Structural Dissociation of the Personality (TSDP), studies of dissociative identity disorder (DID) have documented that two prototypical dissociative subsystems of the personality, the "Emotional Part'' (EP) and the "Apparently Normal Part'' (ANP), have

  16. Generalization of the geometric optical series approach for nonadiabatic scattering problems

    International Nuclear Information System (INIS)

    Herman, M.F.

    1982-01-01

    The geometric optical series approach of Bremmer is generalized for multisurface nonadiabatic scattering problems. This method yields the formal solution of the Schroedinger equation as an infinite series of multiple integrals. The zeroth order term corresponds to WKB propagation on a single adiabatic surface, while the general Nth order term involves N reflections and/or transitions between surfaces accompanied by ''free,'' single surface semiclassical propagation between the points of reflection and transition. Each term is integrated over all possible transition and reflection points. The adiabatic and diabatic limits of this expression are discussed. Numerical results, in which all reflections are ignored, are presented for curve crossing and noncrossing problems. These results are compared to exact quantum results and are shown to be highly accurate

  17. A practical approach to temperature effects in dissociative electron attachment cross sections using local complex potential theory

    International Nuclear Information System (INIS)

    Sugioka, Yuji; Takayanagi, Toshiyuki

    2012-01-01

    Highlights: ► Dissociative electron attachment cross sections for polyatomic molecules are calculated by a simple theoretical approach. ► Temperature effects can be reasonably reproduced with the present model. ► All the degrees-of-freedom are taken into account in the present dynamics approach. -- Abstract: We propose a practical computational scheme to obtain temperature dependence of dissociative electron attachment cross sections to polyatomic molecules within a local complex potential theory formalism. First we perform quantum path-integral molecular dynamics simulations on the potential energy surface for the neutral molecule in order to sample initial nuclear configurations as well as momenta. Classical trajectories are subsequently integrated on the potential energy surface for the anionic state and survival probabilities are simultaneously calculated along the obtained trajectories. We have applied this simple scheme to dissociative electron attachment processes to H 2 O and CF 3 Cl, for which several previous studies are available from both the experimental and theoretical sides.

  18. Phosphorylation of the centrosomal protein, Cep169, by Cdk1 promotes its dissociation from centrosomes in mitosis.

    Science.gov (United States)

    Mori, Yusuke; Inoue, Yoko; Taniyama, Yuki; Tanaka, Sayori; Terada, Yasuhiko

    2015-12-25

    Cep169 is a centrosomal protein conserved among vertebrates. In our previous reports, we showed that mammalian Cep169 interacts and collaborates with CDK5RAP2 to regulate microtubule (MT) dynamics and stabilization. Although Cep169 is required for MT regulation, its precise cellular function remains largely elusive. Here we show that Cep169 associates with centrosomes during interphase, but dissociates from these structures from the onset of mitosis, although CDK5RAP2 (Cep215) is continuously located at the centrosomes throughout cell cycle. Interestingly, treatment with purvalanol A, a Cdk1 inhibitor, nearly completely blocked the dissociation of Cep169 from centrosomes during mitosis. In addition, mass spectrometry analyses identified 7 phosphorylated residues of Cep169 corresponding to consensus phosphorylation sequence for Cdk1. These data suggest that the dissociation of Cep169 from centrosomes is controlled by Cdk1/Cyclin B during mitosis, and that Cep169 might regulate MT dynamics of mitotic spindle. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. A practical approach to temperature effects in dissociative electron attachment cross sections using local complex potential theory

    Energy Technology Data Exchange (ETDEWEB)

    Sugioka, Yuji [Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570 (Japan); Takayanagi, Toshiyuki, E-mail: tako@mail.saitama-u.ac.jp [Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570 (Japan)

    2012-09-11

    Highlights: Black-Right-Pointing-Pointer Dissociative electron attachment cross sections for polyatomic molecules are calculated by a simple theoretical approach. Black-Right-Pointing-Pointer Temperature effects can be reasonably reproduced with the present model. Black-Right-Pointing-Pointer All the degrees-of-freedom are taken into account in the present dynamics approach. -- Abstract: We propose a practical computational scheme to obtain temperature dependence of dissociative electron attachment cross sections to polyatomic molecules within a local complex potential theory formalism. First we perform quantum path-integral molecular dynamics simulations on the potential energy surface for the neutral molecule in order to sample initial nuclear configurations as well as momenta. Classical trajectories are subsequently integrated on the potential energy surface for the anionic state and survival probabilities are simultaneously calculated along the obtained trajectories. We have applied this simple scheme to dissociative electron attachment processes to H{sub 2}O and CF{sub 3}Cl, for which several previous studies are available from both the experimental and theoretical sides.

  20. Quantum–classical correspondence in chaotic dynamics of laser-driven atoms

    International Nuclear Information System (INIS)

    Prants, S V

    2017-01-01

    This paper is a review article on some aspects of quantum–classical correspondence in chaotic dynamics of cold atoms interacting with a standing-wave laser field forming an optical lattice. The problem is treated from both (semi)classical and quantum points of view. In both approaches, the interaction of an atomic electic dipole with the laser field is treated quantum mechanically. Translational motion is described, at first, classically (atoms are considered to be point-like objects) and then quantum mechanically as a propagation of matter waves. Semiclassical equations of motion are shown to be chaotic in the sense of classical dynamical chaos. Point-like atoms in an absolutely deterministic and rigid optical lattice can move in a random-like manner demonstrating a chaotic walking with typical features of classical chaos. This behavior is explained by random-like ‘jumps’ of one of the atomic internal variable when atoms cross nodes of the standing wave and occurs in a specific range of the atom-field detuning. When treating atoms as matter waves, we show that they can make nonadiabatic transitions when crossing the standing-wave nodes. The point is that atomic wave packets split at each node in the same range of the atom-field detuning where the classical chaos occurs. The key point is that the squared amplitude of those semiclassical ‘jumps’ equal to the quantum Landau–Zener parameter which defines the probability of nonadiabatic transitions at the nodes. Nonadiabatic atomic wave packets are much more complicated compared to adiabatic ones and may be called chaotic in this sense. A few possible experiments to observe some manifestations of classical and quantum chaos with cold atoms in horizontal and vertical optical lattices are proposed and discussed. (paper)

  1. Dissociative photoionization of molecular hydrogen. A joint experimental and theoretical study of the electron-electron correlations induced by XUV photoionization and nuclear dynamics on IR-laser dressed transition states

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Andreas

    2015-01-13

    In this thesis, the dissociative single-ionization of molecular hydrogen is investigated in a kinematically complete experiment by employing extreme ultraviolet attosecond pulse trains and infrared femtosecond laser pulses. Induced by the absorption of a single XUV photon, a pronounced energy-dependent asymmetry of the relative emission direction of the photoelectron and the ion is observed. The asymmetry pattern is explained in terms of an interference of two ionization pathways involving a doubly-excited state. This interpretation is validated by a semi-classical model which only takes the nuclear motion into account. Using this model and the observed asymmetry, it is furthermore possible to disentangle the two dissociation pathways which allows for the determination of the autoionization lifetime of the contributing doubly-excited state as a function of the internuclear distance. Moreover, using a pump-probe experiment the dissociation dynamics of molecular hydrogen is investigated. A time-delay dependent momentum distribution of the fragments is observed. With a combined quantum mechanical and semi-classical approach the mechanism giving rise to the observed time-dependence is identified in terms of an intuitive elevator mechanism.

  2. Dissociative, depressive, and PTSD symptom severity as correlates of nonsuicidal self-injury and suicidality in dissociative disorder patients.

    Science.gov (United States)

    Webermann, Aliya R; Myrick, Amie C; Taylor, Christina L; Chasson, Gregory S; Brand, Bethany L

    2016-01-01

    The present study investigates whether symptom severity can distinguish patients diagnosed with dissociative identity disorder and dissociative disorder not otherwise specified with a recent history of nonsuicidal self-injury (NSSI) and suicide attempts from those patients without recent self-harm. A total of 241 clinicians reported on recent history of patient NSSI and suicide attempts. Of these clinicians' patients, 221 completed dissociative, depressive, and posttraumatic stress disorder symptomatology measures. Baseline cross-sectional data from a naturalistic and prospective study of dissociative disorder patients receiving community treatment were utilized. Analyses evaluated dissociative, depressive, and posttraumatic stress disorder symptom severity as methods of classifying patients into NSSI and suicide attempt groupings. Results indicated that dissociation severity accurately classified patients into NSSI and suicidality groups, whereas depression severity accurately classified patients into NSSI groups. These findings point to dissociation and depression severity as important correlates of NSSI and suicidality in patients with dissociative disorders and have implications for self-harm prevention and treatment.

  3. Quantum transition probabilities during a perturbing pulse: Differences between the nonadiabatic results and Fermi's golden rule forms

    Science.gov (United States)

    Mandal, Anirban; Hunt, Katharine L. C.

    2018-05-01

    For a perturbed quantum system initially in the ground state, the coefficient ck(t) of excited state k in the time-dependent wave function separates into adiabatic and nonadiabatic terms. The adiabatic term ak(t) accounts for the adjustment of the original ground state to form the new ground state of the instantaneous Hamiltonian H(t), by incorporating excited states of the unperturbed Hamiltonian H0 without transitions; ak(t) follows the adiabatic theorem of Born and Fock. The nonadiabatic term bk(t) describes excitation into another quantum state k; bk(t) is obtained as an integral containing the time derivative of the perturbation. The true transition probability is given by |bk(t)|2, as first stated by Landau and Lifshitz. In this work, we contrast |bk(t)|2 and |ck(t)|2. The latter is the norm-square of the entire excited-state coefficient which is used for the transition probability within Fermi's golden rule. Calculations are performed for a perturbing pulse consisting of a cosine or sine wave in a Gaussian envelope. When the transition frequency ωk0 is on resonance with the frequency ω of the cosine wave, |bk(t)|2 and |ck(t)|2 rise almost monotonically to the same final value; the two are intertwined, but they are out of phase with each other. Off resonance (when ωk0 ≠ ω), |bk(t)|2 and |ck(t)|2 differ significantly during the pulse. They oscillate out of phase and reach different maxima but then fall off to equal final values after the pulse has ended, when ak(t) ≡ 0. If ωk0 ω. While the transition probability is rising, the midpoints between successive maxima and minima fit Gaussian functions of the form a exp[-b(t - d)2]. To our knowledge, this is the first analysis of nonadiabatic transition probabilities during a perturbing pulse.

  4. Nonadiabatic calculations for tdμ relevant for muon catalyzed fusion

    International Nuclear Information System (INIS)

    Szalewicz, K.; Jeziorski, B.

    1991-01-01

    Due to the mass effect, muonic molecular ions are about 200 times smaller than their electronic counterparts. The proximity of the nuclei in the tdμ ion results in fusion taking place within a picosecond. The properties of this ion are central to understanding the phenomenon of muon catalysis. The authors developed a computational method of solving the nonadiabatic Schroedinger equation for the bound and resonance states of tdμ and its isotopic analogues. The method takes into account both the Coulomb interactions and the strong nuclear forces responsible for the fusion reaction. The wave functions obtained from this method were used to predict very accurately branching ratios and transition rates relevant for various stages of the muon catalytic cycle. Knowledge of these quantities will guide the experiments and help to answer the question of feasibility of net energy production via muon catalysis

  5. Quantum dynamics in open quantum-classical systems.

    Science.gov (United States)

    Kapral, Raymond

    2015-02-25

    Often quantum systems are not isolated and interactions with their environments must be taken into account. In such open quantum systems these environmental interactions can lead to decoherence and dissipation, which have a marked influence on the properties of the quantum system. In many instances the environment is well-approximated by classical mechanics, so that one is led to consider the dynamics of open quantum-classical systems. Since a full quantum dynamical description of large many-body systems is not currently feasible, mixed quantum-classical methods can provide accurate and computationally tractable ways to follow the dynamics of both the system and its environment. This review focuses on quantum-classical Liouville dynamics, one of several quantum-classical descriptions, and discusses the problems that arise when one attempts to combine quantum and classical mechanics, coherence and decoherence in quantum-classical systems, nonadiabatic dynamics, surface-hopping and mean-field theories and their relation to quantum-classical Liouville dynamics, as well as methods for simulating the dynamics.

  6. Oxygen adsorption and dissociation during the oxidation of monolayer Ti2C

    KAUST Repository

    Gan, Liyong

    2013-08-20

    Exfoliated two-dimensional early transition metal carbides and carbonitrides are usually not terminated by metal atoms but saturated by O, OH, and/or F, thus making it difficult to understand the surface structure evolution and the induced electronic modifications. To fill this gap, density functional theory and molecular dynamics simulations are performed to capture the initial stage of the oxidation process of Ti2C, a prototypical example from the recently fabricated class of two-dimensional carbides and carbonitrides. It is shown that the unsaturated Ti 3d orbitals of the pristine Ti2C surface interact strongly with the approaching O2 molecules, resulting in barrierless O2 dissociation. The diffusion of the dissociated O atoms is also found to be very facile. Molecular dynamics simulations suggest that both dissociation and diffusion are enhanced as the O2 coverage increases to 0.25 monolayer. For a coverage of less than 0.11 monolayer, the adsorbates lead to a minor modification of the electronic properties of Ti2C, while the modification is remarkable at 0.25 monolayer. The formed Ti2CO2 after O saturation is an indirect narrow gap semiconductor (0.33 eV) with high intrinsic carrier concentration at room temperature and high thermodynamic stability at intermediate temperature (e.g., 550 °C).

  7. Oxygen adsorption and dissociation during the oxidation of monolayer Ti2C

    KAUST Repository

    Gan, Liyong; Huang, Dan; Schwingenschlö gl, Udo

    2013-01-01

    Exfoliated two-dimensional early transition metal carbides and carbonitrides are usually not terminated by metal atoms but saturated by O, OH, and/or F, thus making it difficult to understand the surface structure evolution and the induced electronic modifications. To fill this gap, density functional theory and molecular dynamics simulations are performed to capture the initial stage of the oxidation process of Ti2C, a prototypical example from the recently fabricated class of two-dimensional carbides and carbonitrides. It is shown that the unsaturated Ti 3d orbitals of the pristine Ti2C surface interact strongly with the approaching O2 molecules, resulting in barrierless O2 dissociation. The diffusion of the dissociated O atoms is also found to be very facile. Molecular dynamics simulations suggest that both dissociation and diffusion are enhanced as the O2 coverage increases to 0.25 monolayer. For a coverage of less than 0.11 monolayer, the adsorbates lead to a minor modification of the electronic properties of Ti2C, while the modification is remarkable at 0.25 monolayer. The formed Ti2CO2 after O saturation is an indirect narrow gap semiconductor (0.33 eV) with high intrinsic carrier concentration at room temperature and high thermodynamic stability at intermediate temperature (e.g., 550 °C).

  8. The Shutdown Dissociation Scale (Shut-D)

    Science.gov (United States)

    Schalinski, Inga; Schauer, Maggie; Elbert, Thomas

    2015-01-01

    The evolutionary model of the defense cascade by Schauer and Elbert (2010) provides a theoretical frame for a short interview to assess problems underlying and leading to the dissociative subtype of posttraumatic stress disorder. Based on known characteristics of the defense stages “fright,” “flag,” and “faint,” we designed a structured interview to assess the vulnerability for the respective types of dissociation. Most of the scales that assess dissociative phenomena are designed as self-report questionnaires. Their items are usually selected based on more heuristic considerations rather than a theoretical model and thus include anything from minor dissociative experiences to major pathological dissociation. The shutdown dissociation scale (Shut-D) was applied in several studies in patients with a history of multiple traumatic events and different disorders that have been shown previously to be prone to symptoms of dissociation. The goal of the present investigation was to obtain psychometric characteristics of the Shut-D (including factor structure, internal consistency, retest reliability, predictive, convergent and criterion-related concurrent validity). A total population of 225 patients and 68 healthy controls were accessed. Shut-D appears to have sufficient internal reliability, excellent retest reliability, high convergent validity, and satisfactory predictive validity, while the summed score of the scale reliably separates patients with exposure to trauma (in different diagnostic groups) from healthy controls. The Shut-D is a brief structured interview for assessing the vulnerability to dissociate as a consequence of exposure to traumatic stressors. The scale demonstrates high-quality psychometric properties and may be useful for researchers and clinicians in assessing shutdown dissociation as well as in predicting the risk of dissociative responding. PMID:25976478

  9. The Shutdown Dissociation Scale (Shut-D

    Directory of Open Access Journals (Sweden)

    Inga Schalinski

    2015-05-01

    Full Text Available The evolutionary model of the defense cascade by Schauer and Elbert (2010 provides a theoretical frame for a short interview to assess problems underlying and leading to the dissociative subtype of posttraumatic stress disorder. Based on known characteristics of the defense stages “fright,” “flag,” and “faint,” we designed a structured interview to assess the vulnerability for the respective types of dissociation. Most of the scales that assess dissociative phenomena are designed as self-report questionnaires. Their items are usually selected based on more heuristic considerations rather than a theoretical model and thus include anything from minor dissociative experiences to major pathological dissociation. The shutdown dissociation scale (Shut-D was applied in several studies in patients with a history of multiple traumatic events and different disorders that have been shown previously to be prone to symptoms of dissociation. The goal of the present investigation was to obtain psychometric characteristics of the Shut-D (including factor structure, internal consistency, retest reliability, predictive, convergent and criterion-related concurrent validity.A total population of 225 patients and 68 healthy controls were accessed. Shut-D appears to have sufficient internal reliability, excellent retest reliability, high convergent validity, and satisfactory predictive validity, while the summed score of the scale reliably separates patients with exposure to trauma (in different diagnostic groups from healthy controls.The Shut-D is a brief structured interview for assessing the vulnerability to dissociate as a consequence of exposure to traumatic stressors. The scale demonstrates high-quality psychometric properties and may be useful for researchers and clinicians in assessing shutdown dissociation as well as in predicting the risk of dissociative responding.

  10. The Dissociative Subtype of Posttraumatic Stress Disorder (PTSD) Among Adolescents: Co-Occurring PTSD, Depersonalization/Derealization, and Other Dissociation Symptoms.

    Science.gov (United States)

    Choi, Kristen R; Seng, Julia S; Briggs, Ernestine C; Munro-Kramer, Michelle L; Graham-Bermann, Sandra A; Lee, Robert C; Ford, Julian D

    2017-12-01

    The purpose of this study was to examine the co-occurrence of posttraumatic stress disorder (PTSD) and dissociation in a clinical sample of trauma-exposed adolescents by evaluating evidence for the depersonalization/derealization dissociative subtype of PTSD as defined by the DSM-5 and then examining a broader set of dissociation symptoms. A sample of treatment-seeking, trauma-exposed adolescents 12 to 16 years old (N = 3,081) from the National Child Traumatic Stress Network Core Data Set was used to meet the study objectives. Two models of PTSD/dissociation co-occurrence were estimated using latent class analysis, one with 2 dissociation symptoms and the other with 10 dissociation symptoms. After model selection, groups within each model were compared on demographics, trauma characteristics, and psychopathology. Model A, the depersonalization/derealization model, had 5 classes: dissociative subtype/high PTSD; high PTSD; anxious arousal; dysphoric arousal; and a low symptom/reference class. Model B, the expanded dissociation model, identified an additional class characterized by dissociative amnesia and detached arousal. These 2 models provide new information about the specific ways PTSD and dissociation co-occur and illuminate some differences between adult and adolescent trauma symptom expression. A dissociative subtype of PTSD can be distinguished from PTSD alone in adolescents, but assessing a wider range of dissociative symptoms is needed to fully characterize adolescent traumatic stress responses. Copyright © 2017 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.

  11. Dissociation Energies of Diatomic Molecules

    International Nuclear Information System (INIS)

    Qun-Chao, Fan; Wei-Guo, Sun

    2008-01-01

    Molecular dissociation energies of 10 electronic states of alkali molecules of KH, 7 LiD, 7 LiH, 6 LiH, NaK, NaLi and NaRb are studied using the highest three accurate vibrational energies of each electronic state, and an improved parameter-free analytical formula which is obtained starting from the LeRoy–Bernstein vibrational energy expression near the dissociation limit. The results show that as long as the highest three vibrational energies are accurate, the current analytical formula will give accurate theoretical dissociation energies D e theory , which are in excellent agreement with the experimental dissociation energies D e expt . (atomic and molecular physics)

  12. Photofragment translational spectroscopy of three body dissociations and free radicals

    Energy Technology Data Exchange (ETDEWEB)

    North, Simon William [Univ. of California, Berkeley, CA (United States)

    1995-04-01

    This dissertation describes several three-body dissociations and the photodissociation of methyl radicals studied using photofragment translational spectroscopy. The first chapter provides an introduction to three body dissociation, examines current experimental methodology, and includes a discussion on the treatment of photofragment translational spectroscopy data arising from three-body fragmentation. The ultraviolet photodissociation of azomethane into two methyl radicals and nitrogen is discussed in chapter 2. Chapter 3 describes the photodissociation of acetone at 248 nm and 193 nm. At 248 nm the translational energy release from the initial C-C bond cleavage matches the exit barrier height and a comparison with results at 266 nm suggests that T> is invariant to the available energy. A fraction of the nascent CH3CO radicals spontaneously dissociate following rotational averaging. The T> for the second C-C bond cleavage also matches the exit barrier height. At 193 nm the experimental data can be successfully fit assuming that the dynamics are analogous to those at 248 nm. A simplified model of energy partitioning which adequately describes the experimental results is discussed. Experiments on acetyl halides provide additional evidence to support the proposed acetone dissociation mechanism. A value of 17.0±1.0 kcal/mole for the barrier height, CH3CO decomposition has been determined. The photodissociation of methyl radical at 193 nm and 212.8 nm is discussed in the chapter 5. The formation of CH2(1Al) and H (2S) was the only single photon dissociation pathway observed at both wavelengths.

  13. Nonadiabatic Dynamics in Single-Electron Tunneling Devices with Time-Dependent Density-Functional Theory

    Science.gov (United States)

    Dittmann, Niklas; Splettstoesser, Janine; Helbig, Nicole

    2018-04-01

    We simulate the dynamics of a single-electron source, modeled as a quantum dot with on-site Coulomb interaction and tunnel coupling to an adjacent lead in time-dependent density-functional theory. Based on this system, we develop a time-nonlocal exchange-correlation potential by exploiting analogies with quantum-transport theory. The time nonlocality manifests itself in a dynamical potential step. We explicitly link the time evolution of the dynamical step to physical relaxation timescales of the electron dynamics. Finally, we discuss prospects for simulations of larger mesoscopic systems.

  14. Dissociative amnesia in dissociative disorders and borderline personality disorder: self-rating assessment in a college population.

    Science.gov (United States)

    Sar, Vedat; Alioğlu, Firdevs; Akyuz, Gamze; Karabulut, Sercan

    2014-01-01

    Dissociative amnesia (DA) among subjects with a dissociative disorder and/or borderline personality disorder (BPD) recruited from a nonclinical population was examined. The Steinberg Dissociative Amnesia Questionnaire (SDAQ), the Childhood Trauma Questionnaire, and the self-report screening tool of the BPD section of the Structured Clinical Interview for DSM-IV(SCID-BPD) were administered to 1,301 college students. A total of 80 participants who were diagnosed with BPD according to the clinician-administered SCID-BPD and 111 nonborderline controls were evaluated using the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D) by a psychiatrist blind to diagnosis and scale scores. Internal consistency analyses and test-retest evaluations suggested that the SDAQ is a reliable instrument for the population studied. Of the participants, 20.6% reported an SDAQ score of 20 or above and impairment by DA. Those who had both dissociative disorder and BPD (n = 78) had the highest SDAQ scores. Both disorders had significant effects on the SCID-D total and amnesia scores in the variance analysis. On SDAQ scores, however, only BPD had this effect. There was a significant interaction between the 2 disorders for the SCID-D total but not for the SDAQ or SCID-D amnesia scores. BPD represented the severity of dissociation and childhood trauma in this study group. However, in contrast to the dissociative disorders, BPD was characterized by better awareness of DA in self-report. The discrepancies between self-report and clinical interview associated with BPD and dissociative disorders are discussed in the context of betrayal theory (J. J. Freyd, 1994) of BPD and perceptual theory (D. B. Beere, 2009) of dissociative disorders.

  15. Barrierless association of CF2 and dissociation of C2F4 by variational transition-state theory and system-specific quantum Rice–Ramsperger–Kassel theory

    Science.gov (United States)

    Bao, Junwei Lucas; Zhang, Xin

    2016-01-01

    Bond dissociation is a fundamental chemical reaction, and the first principles modeling of the kinetics of dissociation reactions with a monotonically increasing potential energy along the dissociation coordinate presents a challenge not only for modern electronic structure methods but also for kinetics theory. In this work, we use multifaceted variable-reaction-coordinate variational transition-state theory (VRC-VTST) to compute the high-pressure limit dissociation rate constant of tetrafluoroethylene (C2F4), in which the potential energies are computed by direct dynamics with the M08-HX exchange correlation functional. To treat the pressure dependence of the unimolecular rate constants, we use the recently developed system-specific quantum Rice–Ramsperger–Kassel theory. The calculations are carried out by direct dynamics using an exchange correlation functional validated against calculations that go beyond coupled-cluster theory with single, double, and triple excitations. Our computed dissociation rate constants agree well with the recent experimental measurements. PMID:27834727

  16. Effects of electrostatic interactions on ligand dissociation kinetics

    Science.gov (United States)

    Erbaş, Aykut; de la Cruz, Monica Olvera; Marko, John F.

    2018-02-01

    We study unbinding of multivalent cationic ligands from oppositely charged polymeric binding sites sparsely grafted on a flat neutral substrate. Our molecular dynamics simulations are suggested by single-molecule studies of protein-DNA interactions. We consider univalent salt concentrations spanning roughly a 1000-fold range, together with various concentrations of excess ligands in solution. To reveal the ionic effects on unbinding kinetics of spontaneous and facilitated dissociation mechanisms, we treat electrostatic interactions both at a Debye-Hückel (DH) (or implicit ions, i.e., use of an electrostatic potential with a prescribed decay length) level and by the more precise approach of considering all ionic species explicitly in the simulations. We find that the DH approach systematically overestimates unbinding rates, relative to the calculations where all ion pairs are present explicitly in solution, although many aspects of the two types of calculation are qualitatively similar. For facilitated dissociation (FD) (acceleration of unbinding by free ligands in solution) explicit-ion simulations lead to unbinding at lower free-ligand concentrations. Our simulations predict a variety of FD regimes as a function of free-ligand and ion concentrations; a particularly interesting regime is at intermediate concentrations of ligands where nonelectrostatic binding strength controls FD. We conclude that explicit-ion electrostatic modeling is an essential component to quantitatively tackle problems in molecular ligand dissociation, including nucleic-acid-binding proteins.

  17. Increasing the productivity of glycopeptides analysis by using higher-energy collision dissociation-accurate mass-product-dependent electron transfer dissociation.

    Science.gov (United States)

    Saba, Julian; Dutta, Sucharita; Hemenway, Eric; Viner, Rosa

    2012-01-01

    Currently, glycans are attracting attention from the scientific community as potential biomarkers or as posttranslational modifications (PTMs) of therapeutic proteins. However, structural characterization of glycoproteins and glycopeptides remains analytically challenging. Here, we report on the implementation of a novel acquisition strategy termed higher-energy collision dissociation-accurate mass-product-dependent electron transfer dissociation (HCD-PD-ETD) on a hybrid linear ion trap-orbitrap mass spectrometer. This acquisition strategy uses the complementary fragmentations of ETD and HCD for glycopeptides analysis in an intelligent fashion. Furthermore, the approach minimizes user input for optimizing instrumental parameters and enables straightforward detection of glycopeptides. ETD spectra are only acquired when glycan oxonium ions from MS/MS HCD are detected. The advantage of this approach is that it streamlines data analysis and improves dynamic range and duty cycle. Here, we present the benefits of HCD-PD-ETD relative to the traditional alternating HCD/ETD for a trainer set containing twelve-protein mixture with two glycoproteins: human serotransferrin, ovalbumin and contaminations of two other: bovine alpha 1 acid glycoprotein (bAGP) and bovine fetuin.

  18. The role of dissociation channels of excited electronic states in quantum optimal control of ozone isomerization: A three-state dynamical model

    Energy Technology Data Exchange (ETDEWEB)

    Kurosaki, Yuzuru, E-mail: kurosaki.yuzuru@jaea.go.jp [Quantum Beam Science Directorate, Tokai Research and Development Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Ho, Tak-San, E-mail: tsho@Princeton.EDU [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Rabitz, Herschel, E-mail: hrabitz@Princeton.EDU [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States)

    2016-05-01

    The prospect of performing the open → cyclic ozone isomerization has attracted much research attention. Here we explore this consideration theoretically by performing quantum optimal control calculations to demonstrate the important role that excited-state dissociation channels could play in the isomerization transformation. In the calculations we use a three-state, one-dimensional dynamical model constructed from the lowest five {sup 1}A′ potential energy curves obtained with high-level ab initio calculations. Besides the laser field-dipole couplings between all three states, this model also includes the diabatic coupling between the two excited states at an avoided crossing leading to competing dissociation channels that can further hinder the isomerization process. The present three-state optimal control simulations examine two possible control pathways previously considered in a two-state model, and reveal that only one of the pathways is viable, achieving a robust ∼95% yield to the cyclic target in the three-state model. This work represents a step towards an ultimate model for the open → cyclic ozone transformation capable of giving adequate guidance about the necessary experimental control field resources as well as an estimate of the ro-vibronic spectral character of cyclic ozone as a basis for an appropriate probe of its formation.

  19. [Clinical Handling of Patients with Dissociative Disorders].

    Science.gov (United States)

    Okano, Kenichiro

    2015-01-01

    This paper discusses the way informed psychiatrists are expected to handle dissociative patients in clinical situations, with a specific focus on dissociative identity disorders and dissociative fugue. On the initial interview with dissociative patients, information on their history of trauma and any nascent dissociative symptoms in their childhood should be carefully obtained. Their level of stress in their current life should also be assessed in order to understand their symptomatology, as well as to predict their future clinical course. A psychoeducational approach is crucial; it might be helpful to give information on dissociative disorder to these patients as well as their family members in order to promote their adherence to treatment. Regarding the symptomatology of dissociative disorders, detailed symptoms and the general clinical course are presented. It was stressed that dissociative identity disorder and dissociative fugue, the most high-profile dissociative disorders, are essentially different in their etiology and clinical presentation. Dissociative disorders are often confused with and misdiagnosed as psychotic disorders, such as schizophrenia. Other conditions considered in terms of the differential diagnosis include borderline personality disorder as well as temporal lobe epilepsy. Lastly, the therapeutic approach to dissociative identity disorder is discussed. Each dissociative identity should be understood as potentially representing some traumatically stressful event in the past. The therapist should be careful not to excessively promote the creation or elaboration of any dissociative identities. Three stages are proposed in the individual psychotherapeutic process. In the initial stage, a secure environment and stabilization of symptoms should be sought. The second stage consists of aiding the "host" personality to make use of other more adaptive coping skills in their life. The third stage involves coaching as well as continuous awareness of

  20. Theoretical Investigation of Hydrogen Adsorption and Dissociation on Iron and Iron Carbide Surfaces Using the ReaxFF Reactive Force Field Method

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Chenyu; van Duin, Adri C.T.; Sorescu, Dan C.

    2012-06-01

    We have developed a ReaxFF reactive force field to describe hydrogen adsorption and dissociation on iron and iron carbide surfaces relevant for simulation of Fischer–Tropsch (FT) synthesis on iron catalysts. This force field enables large system (>>1000 atoms) simulations of hydrogen related reactions with iron. The ReaxFF force field parameters are trained against a substantial amount of structural and energetic data including the equations of state and heats of formation of iron and iron carbide related materials, as well as hydrogen interaction with iron surfaces and different phases of bulk iron. We have validated the accuracy and applicability of ReaxFF force field by carrying out molecular dynamics simulations of hydrogen adsorption, dissociation and recombination on iron and iron carbide surfaces. The barriers and reaction energies for molecular dissociation on these two types of surfaces have been compared and the effect of subsurface carbon on hydrogen interaction with iron surface is evaluated. We found that existence of carbon atoms at subsurface iron sites tends to increase the hydrogen dissociation energy barrier on the surface, and also makes the corresponding hydrogen dissociative state relatively more stable compared to that on bare iron. These properties of iron carbide will affect the dissociation rate of H{sub 2} and will retain more surface hydride species, thus influencing the dynamics of the FT synthesis process.

  1. Dissociation of ethane by electron impact

    International Nuclear Information System (INIS)

    Winters, H.F.

    1979-01-01

    The absolute total dissociation cross section for ethane is reported for electron energies between 10 and 600 eV. A maximum value of 7.6 X 10 -16 cm 2 occurs at 80 eV while the apparent threshold is approximately 10 eV. Dissociative ionization is more probable than dissociation into neutral fragments at all energies except in the threshold region. The data indicates that fragmentation involving methane elimination (e - +C 2 H 6 → CH 4 + CH 2 ) occurs in less than 2% of the dissociative events for 50 < E < 600 eV. Arguments are presented which suggest that some of the lower excited states of ethane are stable against dissociation. (Auth.)

  2. Reconsidering the autohypnotic model of the dissociative disorders.

    Science.gov (United States)

    Dell, Paul F

    2018-03-22

    The dissociative disorders field and the hypnosis field currently reject the autohypnotic model of the dissociative disorders, largely because many correlational studies have shown hypnotizability and dissociation to be minimally related (r = .12). Curiously, it is also widely accepted that dissociative patients are highly hypnotizable. If dissociative patients are highly hypnotizable because only highly hypnotizable individuals can develop a dissociative disorder - as the author proposes - then the methodology of correlational studies of hypnotizability and dissociation in random clinical and community samples would necessarily be constitutively unable to detect, and statistically unable to reflect, that fact. That is, the autohypnotic, dissociative distancing of that small subset of highly hypnotizable individuals who repeatedly encountered intolerable circumstances is statistically lost among the data of (1) the highly hypnotizable subjects who do not dissociate and (2) subjects (of all levels of hypnotizability) who manifest other kinds of dissociation. The author proposes that, when highly hypnotizable individuals repeatedly engage in autohypnotic distancing from intolerable circumstances, they develop an overlearned, highly-motivated, automatized pattern of dissociative self-protection (i.e., a dissociative disorder). The author urges that theorists of hypnosis and the dissociative disorders explicitly include in their theories (a) the trait of high hypnotizability, (b) the phenomena of autohypnosis, and (c) the manifestations of systematized, autohypnotic pathology. Said differently, the author is suggesting that autohypnosis and autohypnotic pathology are unacknowledged nodes in the nomothetic networks of both hypnosis and dissociation.

  3. Electron beam induced deposition of silacyclohexane and dichlorosilacyclohexane: the role of dissociative ionization and dissociative electron attachment in the deposition process

    Directory of Open Access Journals (Sweden)

    Ragesh Kumar T P

    2017-11-01

    Full Text Available We present first experiments on electron beam induced deposition of silacyclohexane (SCH and dichlorosilacyclohexane (DCSCH under a focused high-energy electron beam (FEBID. We compare the deposition dynamics observed when growing pillars of high aspect ratio from these compounds and we compare the proximity effect observed for these compounds. The two precursors show similar behaviour with regards to fragmentation through dissociative ionization in the gas phase under single-collision conditions. However, while DCSCH shows appreciable cross sections with regards to dissociative electron attachment, SCH is inert with respect to this process. We discuss our deposition experiments in context of the efficiency of these different electron-induced fragmentation processes. With regards to the deposition dynamics, we observe a substantially faster growth from DCSCH and a higher saturation diameter when growing pillars with high aspect ratio. However, both compounds show similar behaviour with regards to the proximity effect. With regards to the composition of the deposits, we observe that the C/Si ratio is similar for both compounds and in both cases close to the initial molecular stoichiometry. The oxygen content in the DCSCH deposits is about double that of the SCH deposits. Only marginal chlorine is observed in the deposits of from DCSCH. We discuss these observations in context of potential approaches for Si deposition.

  4. Testing the diagnosis of dissociative identity disorder through measures of dissociation, absorption, hypnotizability and PTSD: a Norwegian pilot study.

    Science.gov (United States)

    Dale, Karl Yngvar; Berg, Renate; Elden, Ake; Ødegård, Atle; Holte, Arne

    2009-01-01

    A total of 14 women meeting criteria for dissociative identity disorder (DID) based on the Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV]) were compared to a group of women (n = 10) with other dissociative diagnoses and a group of normal controls (n = 14) with regard to dissociativity, absorption, trauma related symptoms and hypnotizability. Both of the clinical groups reported histories of childhood trauma and attained high PTSD scores. The DID group differed significantly from the group with other dissociative diagnoses and the non-diagnosed comparison group with regard to hypnotizability, the variety of dissociative symptomatology, and the magnitude of dissociative symptomatology. However, no significant differences between the two clinical groups were detected with regard to absorption, general dissociative level, or symptoms related to traumatic stress. Results support the notion that DID can be regarded as a clinical entity which is separable from other dissociative disorders. Results also indicated that hypnotizability is the most important clinical feature of DID.

  5. Non-adiabatic description of proton emission from the odd-odd nucleus 130Eu

    Directory of Open Access Journals (Sweden)

    Patial Monika

    2014-03-01

    Full Text Available We discuss the non-adiabatic quasiparticle approach for calculating the rotational spectra and decay width of odd-odd proton emitters. The Coriolis effects are incorporated in both the parent and daughter wave functions. Results for the two probable ground states (1+ and 2+ of the proton emitter 130Eu are discussed. With our calculations, we confirm the proton emitting state to be the Iπ = 1+ state, irrespective of the strength of the Coriolis interaction. This study provides us with an opportunity to look into the details of wave functions of deformed odd-odd nuclei to which the proton emission halflives are quite sensitive.

  6. Aggregation-induced chemical reactions: acid dissociation in growing water clusters.

    Science.gov (United States)

    Forbert, Harald; Masia, Marco; Kaczmarek-Kedziera, Anna; Nair, Nisanth N; Marx, Dominik

    2011-03-23

    Understanding chemical reactivity at ultracold conditions, thus enabling molecular syntheses via interstellar and atmospheric processes, is a key issue in cryochemistry. In particular, acid dissociation and proton transfer reactions are ubiquitous in aqueous microsolvation environments. Here, the full dissociation of a HCl molecule upon stepwise solvation by a small number of water molecules at low temperatures, as relevant to helium nanodroplet isolation (HENDI) spectroscopy, is analyzed in mechanistic detail. It is found that upon successive aggregation of HCl with H(2)O molecules, a series of cyclic heteromolecular structures, up to and including HCl(H(2)O)(3), are initially obtained before a precursor state for dissociation, HCl(H(2)O)(3)···H(2)O, is observed upon addition of a fourth water molecule. The latter partially aggregated structure can be viewed as an "activated species", which readily leads to dissociation of HCl and to the formation of a solvent-shared ion pair, H(3)O(+)(H(2)O)(3)Cl(-). Overall, the process is mostly downhill in potential energy, and, in addition, small remaining barriers are overcome by using kinetic energy released as a result of forming hydrogen bonds due to aggregation. The associated barrier is not ruled by thermal equilibrium but is generated by athermal non-equilibrium dynamics. These "aggregation-induced chemical reactions" are expected to be of broad relevance to chemistry at ultralow temperature much beyond HENDI spectroscopy.

  7. Dissociation in undergraduate students: disruptions in executive functioning.

    Science.gov (United States)

    Giesbrecht, Timo; Merckelbach, Harald; Geraerts, Elke; Smeets, Ellen

    2004-08-01

    The concept of dissociation refers to disruptions in attentional control. Attentional control is an executive function. Few studies have addressed the link between dissociation and executive functioning. Our study investigated this relationship in a sample of undergraduate students (N = 185) who completed the Dissociative Experiences Scale and the Random Number Generation Task. We found that minor disruptions in executive functioning were related to a subclass of dissociative experiences, notably dissociative amnesia and the Dissociative Experiences Scale Taxon. However, the two other subscales of the Dissociative Experiences Scale, measuring depersonalization and absorption, were unrelated to executive functioning. Our findings suggest that a failure to inhibit previous responses might contribute to the pathological memory manifestations of dissociation.

  8. Comparing the symptoms and mechanisms of "dissociation" in dissociative identity disorder and borderline personality disorder.

    Science.gov (United States)

    Laddis, Andreas; Dell, Paul F; Korzekwa, Marilyn

    2017-01-01

    A total of 75 patients were diagnosed with the Structured Clinical Interview for DSM-IV Dissociative Disorders-Revised as having dissociative identity disorder (DID), and 100 patients were diagnosed with the Structured Interview for DSM-IV Personality as having borderline personality disorder (BPD). Both groups were administered the Multidimensional Inventory of Dissociation (MID). DID patients had significantly higher MID scores than BPD patients, different distributions of MID scores, and different MID subscale profiles in 3 ranges of MID scores (0-15, 15-30, 30-45). The core MID symptoms-exhibited at all ranges of MID scores-for DID patients (the presence of alters, identity confusion, and memory problems) and BPD patients (flashbacks, identity confusion, and memory problems) were ostensibly similar but were considered to be mostly produced by different underlying processes. Multiple regression analyses showed that the core MID symptoms of DID patients had different predictors than did the core MID symptoms of BPD patients. Alter identities seemed to generate most-but not all-dissociative phenomena in DID patients, whereas only the 24% highest scoring BPD patients (MID ≥45) seemed to manifest alter-driven dissociative experiences. Most BPD dissociative experiences appeared to be due to 5 other mechanisms: (a) BPD-specific, stress-driven, rapid shifts of self-state; (b and c) nondefensive disruptions of the framework of perceptual organization with or without an accompanying BPD-specific, dissociation-like disintegration of affective/neurocognitive functioning; (d) a defensive distancing or detachment from distress (i.e., simple depersonalization); and (e) Allen, Console, and Lewis's (1999) severe absorptive detachment.

  9. Generating functional analysis of complex formation and dissociation in large protein interaction networks

    International Nuclear Information System (INIS)

    Coolen, A C C; Rabello, S

    2009-01-01

    We analyze large systems of interacting proteins, using techniques from the non-equilibrium statistical mechanics of disordered many-particle systems. Apart from protein production and removal, the most relevant microscopic processes in the proteome are complex formation and dissociation, and the microscopic degrees of freedom are the evolving concentrations of unbound proteins (in multiple post-translational states) and of protein complexes. Here we only include dimer-complexes, for mathematical simplicity, and we draw the network that describes which proteins are reaction partners from an ensemble of random graphs with an arbitrary degree distribution. We show how generating functional analysis methods can be used successfully to derive closed equations for dynamical order parameters, representing an exact macroscopic description of the complex formation and dissociation dynamics in the infinite system limit. We end this paper with a discussion of the possible routes towards solving the nontrivial order parameter equations, either exactly (in specific limits) or approximately.

  10. Second European study conference on molecular low energy collisions (MOLEC II)

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-01

    The conference contained 52 papers on molecular low energy collisions including nonadiabatic transitions and excited states, vibrational and rotational energy transfer, chemical reactions, dissociation and ionization, general methods, potential surfaces, electronic excitation and excited states, inelastic scattering and anisotropic potentials, chemical reactions, and Van der Waals molecules. (JFP)

  11. Correlation diagram approach to the dissociative ionization mechanisms of methanol

    International Nuclear Information System (INIS)

    Momigny, J.; Wankenne, H.; Krier, C.

    1980-01-01

    A systematic survey is made of the dissociation processes from the ground state and from the electronically excited states of CH 3 OH + . Most metastable processes occurring in the mass spectrum of CD 3 OH are studied also, including measurement of the kinetic energy release and appearance potentials. It is shown that if ionic species such as CH 2 OH + , CH 2 O + and HCO + are present in the mass spectrum of CH 3 OH, the isomers CH 3 O + , HCOH + and COH + are also present. The precursors of these ions having been identified by the metastable processes, correlation diagrams are used to show that, from the first ionization potential of CH 3 OH to 14 eV, the only exception being CH 3 O + which results from an electronically spin-forbidden predissociation, the fragment ions can be considered to result from adiabatic decay of the ground state of CH 3 OH + . The potential barriers involved in these adiabatic processes result either from conical intersection or from avoided-crossing between the ground state of CH 3 OH + and the electronically excited states occurring up to 14 eV. At higher energies, many non-adiabatic processes occur; for example, the appearance of CD 2 O + and the electronically excited states of HCO + and COH + ions. It is shown additionally that kinetic energy releases observed in the collision-induced processes CH 3 OH + → CH 2 OH + + H and CH 2 OH + → HCO + + H 2 are in good agreement with the mechanistic approach via the correlation diagram for the appearance of the non-collision-induced ion processes. (orig.)

  12. Inflight dissociation of zircon in air plasma

    Energy Technology Data Exchange (ETDEWEB)

    Yugeswaran, S; Selvarajan, V [Bharathiar University, Coimbatore 641046 (India); Ananthapadmanabhan, P V; Thiyagarajan, T K [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai - 400 085 (India); Nair, Janardhanan [Ion Arc Technologies Pvt Ltd, Coimbatore (India)

    2010-02-01

    Thermal dissociation of zircon can be conveniently carried out in a plasma reactor, which is characterized by high temperature, high energy density and high quench rate. Zirconia is recovered from this partially dissociated zircon by alkali leaching. Dissociation of zircon has been conventionally carried out in argon gas, which is expensive. The present paper reports experimental results on thermal dissociation of zircon in air plasma medium. Process simulation for 'inflight' dissociation of zircon in air plasma medium is also presented. The experimental system consists of a central hollow graphite electrode, which acts as the cathode and a graphite anode. The material to be processed is fed centrally through the cathode. The unique feature of the system is that it uses air as the working gas to generate the thermal plasma. The system has been used to study in-flight dissociation of zircon in the thermal plasma jet. Dissociation was carried out over 10-25 kW power range. Results of the study indicate that complete dissociation of zircon to ZrO{sub 2} and silica could be accomplished at 25 kW in air plasma.

  13. Inflight dissociation of zircon in air plasma

    International Nuclear Information System (INIS)

    Yugeswaran, S; Selvarajan, V; Ananthapadmanabhan, P V; Thiyagarajan, T K; Nair, Janardhanan

    2010-01-01

    Thermal dissociation of zircon can be conveniently carried out in a plasma reactor, which is characterized by high temperature, high energy density and high quench rate. Zirconia is recovered from this partially dissociated zircon by alkali leaching. Dissociation of zircon has been conventionally carried out in argon gas, which is expensive. The present paper reports experimental results on thermal dissociation of zircon in air plasma medium. Process simulation for 'inflight' dissociation of zircon in air plasma medium is also presented. The experimental system consists of a central hollow graphite electrode, which acts as the cathode and a graphite anode. The material to be processed is fed centrally through the cathode. The unique feature of the system is that it uses air as the working gas to generate the thermal plasma. The system has been used to study in-flight dissociation of zircon in the thermal plasma jet. Dissociation was carried out over 10-25 kW power range. Results of the study indicate that complete dissociation of zircon to ZrO 2 and silica could be accomplished at 25 kW in air plasma.

  14. Dissociative Part-Dependent Resting-State Activity in Dissociative Identity Disorder: A Controlled fMRI Perfusion Study

    OpenAIRE

    Schlumpf, Yolanda R.; Reinders, Antje A. T. S.; Nijenhuis, Ellert R. S.; Luechinger, Roger; van Osch, Matthias J. P.; Jäncke, Lutz

    2014-01-01

    Background: In accordance with the Theory of Structural Dissociation of the Personality (TSDP), studies of dissociative identity disorder (DID) have documented that two prototypical dissociative subsystems of the personality, the "Emotional Part'' (EP) and the "Apparently Normal Part'' (ANP), have different biopsychosocial reactions to supraliminal and subliminal trauma-related cues and that these reactions cannot be mimicked by fantasy prone healthy controls nor by actors. Methods: Arterial ...

  15. Variational coupling between q-number and c-number dynamics

    International Nuclear Information System (INIS)

    Amaral, C.M. do; Joffily, S.

    1984-01-01

    The time-dependent quantum variational principle is generalized for the case of hamiltonian operators having real parameters and their time derivates. The obtained variational system is formed by a Schroedinger equation coupled to a Lagrange equation system, where the lagrangian is the average value of the parametrized hamiltonian operator. The consequent dynamics of the variational principle, describes the interaction between a q-number sub-dynamics with a c-number sub-dynamics. In the ((h/2π)) 0 -order W.K.B. approximation, the variational system reduces to a Hamilton-Jacobi-like equation, coupled to a Lagrange equation family. The formal features of the obtained variational system are appropriated for the description of, adiabatics and non-adiabatics, time-dependent q-number c-number interactions. (L.C.) [pt

  16. I Working with dissociative dynamics and the longing for excess in binge eating disorders.

    Science.gov (United States)

    Austin, Sue

    2013-06-01

    In this paper the author describes her work with a woman who, in her mid 20s, sought analysis for her non-vomiting binge eating disorder. The paper explores how two aspects of Jung's view of the psyche as healthily dissociable were used to think about the potential for change contained within the explosive, aggressive energies in this patient's bingeing. The resultant approach takes the patient's splitting defences, dissociations and self-destructive behaviour as a point of access to her unconscious. Seen in this way, these behaviours contain the seeds of recovery and are the starting point for analysis rather than defences against it. The paper also brings a number of Jungian and post-Jungian ideas into conversation with aspects of contemporary thinking about subjectivity, identity and the longing for excess developed by Leo Bersani and Judith Butler. © 2013, The Society of Analytical Psychology.

  17. Deterministic constant-temperature dynamics for dissipative quantum systems

    International Nuclear Information System (INIS)

    Sergi, Alessandro

    2007-01-01

    A novel method is introduced in order to treat the dissipative dynamics of quantum systems interacting with a bath of classical degrees of freedom. The method is based upon an extension of the Nose-Hoover chain (constant temperature) dynamics to quantum-classical systems. Both adiabatic and nonadiabatic numerical calculations on the relaxation dynamics of the spin-boson model show that the quantum-classical Nose-Hoover chain dynamics represents the thermal noise of the bath in an accurate and simple way. Numerical comparisons, both with the constant-energy calculation and with the quantum-classical Brownian motion treatment of the bath, show that the quantum-classical Nose-Hoover chain dynamics can be used to introduce dissipation in the evolution of a quantum subsystem even with just one degree of freedom for the bath. The algorithm can be computationally advantageous in modelling, within computer simulation, the dynamics of a quantum subsystem interacting with complex molecular environments. (fast track communication)

  18. [Questionnaire on dissociative symptoms. German adaptation, reliability and validity of the American Dissociative Experience Scale (DES)].

    Science.gov (United States)

    Freyberger, H J; Spitzer, C; Stieglitz, R D; Kuhn, G; Magdeburg, N; Bernstein-Carlson, E

    1998-06-01

    The "Fragebogen zu dissoziativen Symptomen (FDS)" represents the authorised German translation and adaptation of the "Dissociative Experience Scale" (DES; Bernstein and Putnam 1986). The original scale comprises 28 items covering dissociative experiences with regard to memory, identity, awareness and cognition according to DSM-III-R and DSM-IV. For the German version, 16 items were added to cover dissociative phenomena according to ICD-10, mainly pseudoneurological conversion symptoms. Reliability and validity of the German version were studied in a total sample of 813 persons and were compared to the results of the original version. Test-retest reliability of the FDS was rtt = 0.88 and Cronbach's consistency coefficient was alpha = 0.93, which is comparable to the results of the DES. The instrument differentiates between different samples (healthy control subjects, students, unselected neurological and psychiatric inpatients, neurological and psychiatric patients with a dissociative disorder and schizophrenics). The FDS is an easily applicable, reliable and valid measure to quantify dissociative experiences.

  19. Flow of CO2 ethanol and of CO2 methanol in a non-adiabatic microfluidic T-junction at high pressures

    NARCIS (Netherlands)

    Blanch Ojea, R.; Tiggelaar, Roald M.; Pallares, J.; Grau, F.X.; Gardeniers, Johannes G.E.

    2012-01-01

    In this work, an experimental investigation of the single- and multiphase flows of two sets of fluids, CO2–ethanol and CO2–methanol, in a non-adiabatic microfluidic T-junction is presented. The operating conditions ranged from 7 to 18 MPa, and from 294 to 474 K. The feed mass fraction of CO2 in the

  20. Dissociative Disorders Among Chinese Inpatients Diagnosed With Schizophrenia

    Science.gov (United States)

    Yu, Junhan; Ross, Colin A.; Keyes, Benjamin B.; Li, Ying; Dai, Yunfei; Zhang, Tianhong; Wang, Lanlan; Fan, Qing; Xiao, Zeping

    2010-01-01

    The purpose of the study was to assess the prevalence of dissociative disorders in a sample of Chinese psychiatric inpatients. Participants in the study consisted of 569 consecutively admitted inpatients at Shanghai Mental Health Center, China, of whom 84.9% had a clinical diagnosis of schizophrenia based on the Chinese Classification and Diagnostic Criteria for Mental Disorders, Version 3 (CCMD-3). All participants completed a self-report measure of dissociation, the Dissociative Experiences Scale (DES) and none had a prior diagnosis of a dissociative disorder. Ninety-six randomly selected participants were interviewed with a structured interview, the Dissociative Disorders Interview Schedule (DDIS) and a clinical interview. These 96 patients did not differ significantly from the 473 patients who were not interviewed on any demographic measures or on the self-report measure dissociation. A total of 28 (15.3%, after weighting of the data) patients received a clinical diagnosis of a dissociative disorder based on DSM-IV-TR criteria. Dissociative identity disorder was diagnosed in 2 (0.53%, after weighting) patients. Compared to the patients without a dissociative disorder, patients with dissociative disorders were significantly more likely to report childhood abuse (57.1% versus 22.1%), but the two groups did not differ significantly on any demographic measures. Dissociative disorders were readily identified in an inpatient psychiatric population in China. PMID:20603768

  1. Nonadiabatic heating of the central plasma sheet at substorm onset

    International Nuclear Information System (INIS)

    Huang, C.Y.; Frank, L.A.; Rostoker, G.; Fennell, J.; Mitchell, D.G.

    1992-01-01

    Heating events in the plasma sheet boundary layer and central plasma sheet are found to occur at the onset of expansive phase activity. The main effect is a dramatic increase in plasma temperature, coincident with a partial dipolarization of the magnetic field. Fluxes of energetic particles increase without dispersion during these events which occur at all radial distances up to 23 R E , the apogee of the ISEIE spacecraft. A major difference between these heating events and those observed at geosynchronous distances lies in the heating mechanism which is nonadiabatic beyond 10 R E but may be adiabatic closer to Earth. The energy required to account for the increase in plasma thermal energy is comparable with that required for Joule heating of the ionosphere. The plasma sheet must be considered as a major sink in the energy balance of substorm. The authors estimate lobe magnetic pressures during these events. Changes in lobe pressure are generally not correlated with onsets or intensifications of expansive phase activity

  2. Dissociating the two faces of selective memory retrieval.

    Science.gov (United States)

    Dobler, Ina M; Bäuml, Karl-Heinz T

    2012-07-01

    Research in the past four decades has repeatedly shown that selective retrieval of some (non-target) memories can impair subsequent retrieval of other (target) information, a finding known as retrieval-induced forgetting. More recently, however, there is evidence that selective retrieval can both impair and enhance recall of related memories (K-H. T. Bäuml & Samenieh, 2010). To identify possible experimental dissociations between the detrimental and the beneficial effects of memory retrieval, we examined retrieval dynamics in listwise directed forgetting, varying the delay between preceding non-target and subsequent target recall. When target recall immediately followed non-target recall, we replicated the prior work and found detrimental effects of memory retrieval on to-be-remembered items but beneficial effects on to-be-forgotten items. In contrast, when a delay was introduced between non-target and target recall, the detrimental effects were present but the beneficial effects were absent. The results demonstrate a first experimental dissociation between the two effects of memory retrieval. They are consistent with a recent two-factor account of the two faces of selective memory retrieval.

  3. A comparison of quantum and classical dynamics of H2 dissociation on Cu(111)

    DEFF Research Database (Denmark)

    Kinnersley, A.; Darling, G.R.; Holloway, S.

    1996-01-01

    ground state. This subtracts from the problem the largest quantum degree of freedom with the consequence that broadly speaking, quantum and classical results for the dissociation as a function of initial rotational state and incidence angle agree well. One feature arising from the calculations...

  4. Dissociative Tendencies and Traffic Incidents

    Directory of Open Access Journals (Sweden)

    Valle, Virginia

    2012-01-01

    Full Text Available This paper analyses the relationship between dissociative experiences and road traffic incidents (crashes and traffic tickets in drivers (n=295 from Mar del Plata (Argentina city. A self-report questionnaire was applied to assess traffic crash involvement and sociodemographic variables. Dissociative tendencies were assessed by a modified version of the DES scale. To examine differences in DES scores tests of the difference of means were applied. Drivers who reported to be previously involved in traffic incidents obtained higher puntuations in the dissociative experiences scale than drivers who did not report such events. This result is observed for the total scale and for the three sub-scales (absorption, amnesia and depersonalization. However, differences appeared mainly for minor damage collisions. Further studies are needed to evaluate the role of dissociative tendencies as a risk factor in road traffic safety.

  5. EEG source reconstruction evidence for the noun-verb neural dissociation along semantic dimensions.

    Science.gov (United States)

    Zhao, Bin; Dang, Jianwu; Zhang, Gaoyan

    2017-09-17

    One of the long-standing issues in neurolinguistic research is about the neural basis of word representation, concerning whether grammatical classification or semantic difference causes the neural dissociation of brain activity patterns when processing different word categories, especially nouns and verbs. To disentangle this puzzle, four orthogonalized word categories in Chinese: unambiguous nouns (UN), unambiguous verbs (UV), ambiguous words with noun-biased semantics (AN), and ambiguous words with verb-biased semantics (AV) were adopted in an auditory task for recording electroencephalographic (EEG) signals from 128 electrodes on the scalps of twenty-two subjects. With the advanced current density reconstruction (CDR) algorithm and the constraint of standardized low-resolution electromagnetic tomography, the spatiotemporal brain dynamics of word processing were explored with the results that in multiple time periods including P1 (60-90ms), N1 (100-140ms), P200 (150-250ms) and N400 (350-450ms), noun-verb dissociation over the parietal-occipital and frontal-central cortices appeared not only between the UN-UV grammatical classes but also between the grammatically identical but semantically different AN-AV pairs. The apparent semantic dissociation within one grammatical class strongly suggests that the semantic difference rather than grammatical classification could be interpreted as the origin of the noun-verb neural dissociation. Our results also revealed that semantic dissociation occurs from an early stage and repeats in multiple phases, thus supporting a functionally hierarchical word processing mechanism. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  6. Psychotherapy and pharmacotherapy for patients with dissociative identity disorder.

    Science.gov (United States)

    Gentile, Julie P; Dillon, Kristy S; Gillig, Paulette Marie

    2013-02-01

    There is a wide variety of what have been called "dissociative disorders," including dissociative amnesia, dissociative fugue, depersonalization disorder, dissociative identity disorder, and forms of dissociative disorder not otherwise specified. Some of these diagnoses, particularly dissociative identity disorder, are controversial and have been questioned by many clinicians over the years. The disorders may be under-diagnosed or misdiagnosed, but many persons who have experienced trauma report "dissociative" symptoms. Prevalence of dissociative disorders is unknown, but current estimates are higher than previously thought. This paper reviews clinical, phenomenological, and epidemiological data regarding diagnosis in general, and illustrates possible treatment interventions for dissociative identity disorder, with a focus on psychotherapy interventions and a review of current psychopharmacology recommendations as part of a comprehensive multidisciplinary treatment plan.

  7. Many-body processes in atomic and molecular physics. Progress report, September 1, 1983-August 31, 1984

    International Nuclear Information System (INIS)

    Chu, S.I.

    1984-02-01

    Research is reported on: semiclassical many mode Floquet theory; exact semiclassical treatment of nonlinear multiphoton dissociation; nonadiabatic approach for resonant infrared multiphoton absorption spectroscopy; infrared MPD of triatomic molecules, most probable path approach; and complex-coordinate coupled-Landau-channel method for autoionizing resonances of H atoms in intense magnetic fields

  8. Neurophysiological correlates of dissociative symptoms

    NARCIS (Netherlands)

    Kruijs, van der S.J.M.; Bodde, N.M.G; Carrette, E.C.B.; Lazeron, R.H.C; Vonck, K.E.J.; Boon, P.A.J.M.; Langereis, G.R.; Cluitmans, P.J.M.; Feijs, L.M.G.; Hofman, P.A.M.; Backes, W.H.; Jansen, J.F.A.; Aldenkamp, A.P.

    2014-01-01

    Objective: Dissociation is a mental process with psychological and somatoform manifestations, which is closely related to hypnotic suggestibility and essentially shows the ability to obtain distance from reality. An increased tendency to dissociate is a frequently reported characteristic of patients

  9. Dissociation: a developmental psychoneurobiological perspective

    African Journals Online (AJOL)

    Adele

    ... the stream of con- sciousness and memory.1 It is a frequent symptom of a range ... infant for long time spans in an extremely disturbed psycho- biological state that ... Advantage: Dissociation is adaptive in the short-term. Dissociation can be ...

  10. From dissipative dynamics to studies of heat transfer at the nanoscale: analysis of the spin-boson model.

    Science.gov (United States)

    Boudjada, Nazim; Segal, Dvira

    2014-11-26

    We study in a unified manner the dissipative dynamics and the transfer of heat in the two-bath spin-boson model. We use the Bloch-Redfield (BR) formalism, valid in the very weak system-bath coupling limit, the noninteracting-blip approximation (NIBA), applicable in the nonadiabatic limit, and iterative, numerically exact path integral tools. These methodologies were originally developed for the description of the dissipative dynamics of a quantum system, and here they are applied to explore the problem of quantum energy transport in a nonequilibrium setting. Specifically, we study the weak-to-intermediate system-bath coupling regime at high temperatures kBT/ħ > ε, with ε as the characteristic frequency of the two-state system. The BR formalism and NIBA can lead to close results for the dynamics of the reduced density matrix (RDM) in a certain range of parameters. However, relatively small deviations in the RDM dynamics propagate into significant qualitative discrepancies in the transport behavior. Similarly, beyond the strict nonadiabatic limit NIBA's prediction for the heat current is qualitatively incorrect: It fails to capture the turnover behavior of the current with tunneling energy and temperature. Thus, techniques that proved meaningful for describing the RDM dynamics, to some extent even beyond their rigorous range of validity, should be used with great caution in heat transfer calculations, because qualitative-serious failures develop once parameters are mildly stretched beyond the techniques' working assumptions.

  11. From state dissociation to status dissociatus.

    Science.gov (United States)

    Antelmi, Elena; Ferri, Raffaele; Iranzo, Alex; Arnulf, Isabelle; Dauvilliers, Yves; Bhatia, Kailash P; Liguori, Rocco; Schenck, Carlos H; Plazzi, Giuseppe

    2016-08-01

    The states of being are conventionally defined by the simultaneous occurrence of behavioral, neurophysiological and autonomic descriptors. State dissociation disorders are due to the intrusion of features typical of a different state into an ongoing state. Disorders related to these conditions are classified according to the ongoing main state and comprise: 1) Dissociation from prevailing wakefulness as seen in hypnagogic or hypnopompic hallucinations, automatic behaviors, sleep drunkenness, cataplexy and sleep paralysis 2) Dissociation from rapid eye movement (REM) sleep as seen in REM sleep behavior disorder and lucid dreaming and 3) Dissociation from NREM sleep as seen in the disorders of arousal. The extreme expression of states dissociation is characterized by the asynchronous occurrence of the various components of the different states that prevents the recognition of any state of being. This condition has been named status dissociatus. According to the underlying disorders/diseases and to their severity, among status dissociatus we may recognize disorders in which such an extreme dissociation occurs only at night time or intermittently (i.e., autoimmune encephalopathies, narcolepsy type 1 and IgLON5 parasomnia), and others in which it occurs nearly continuously with complete loss of any conventionally defined state of being, and of the circadian pattern (agrypnia excitata). Here, we render a comprehensive review of all diseases/disorders associated with state dissociation and status dissociatus and propose a critical classification of this complex scenario. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Dissociation: Defining the Concept in Criminal Forensic Psychiatry.

    Science.gov (United States)

    Bourget, Dominique; Gagné, Pierre; Wood, Stephen Floyd

    2017-06-01

    Claims of amnesia and dissociative experiences in association with a violent crime are not uncommon. Research has shown that dissociation is a risk factor for violence and is seen most often in crimes of extreme violence. The subject matter is most relevant to forensic psychiatry. Peritraumatic dissociation for instance, with or without a history of dissociative disorder, is quite frequently reported by offenders presenting for a forensic psychiatric examination. Dissociation or dissociative amnesia for serious offenses can have legal repercussions stemming from their relevance to the legal constructs of fitness to stand trial, criminal responsibility, and diminished capacity. The complexity in forensic psychiatric assessments often lies in the difficulty of connecting clinical symptomatology reported by violent offenders to a specific condition included in the Diagnostic and Statistical Manual of Mental Disorders (DSM). This article provides a review of diagnostic considerations with regard to dissociation across the DSM nomenclature, with a focus on the main clinical constructs related to dissociation. Forensic implications are discussed, along with some guides for the forensic evaluator of offenders presenting with dissociation. © 2017 American Academy of Psychiatry and the Law.

  13. Psychotherapy and Pharmacotherapy for Patients with Dissociative Identity Disorder

    OpenAIRE

    Gentile, Julie P.; Dillon, Kristy S.; Gillig, Paulette Marie

    2013-01-01

    There is a wide variety of what have been called “dissociative disorders,” including dissociative amnesia, dissociative fugue, depersonalization disorder, dissociative identity disorder, and forms of dissociative disorder not otherwise specified. Some of these diagnoses, particularly dissociative identity disorder, are controversial and have been questioned by many clinicians over the years. The disorders may be under-diagnosed or misdiagnosed, but many persons who have experienced trauma rep...

  14. Dissociative depression among women in the community.

    Science.gov (United States)

    Sar, Vedat; Akyüz, Gamze; Oztürk, Erdinç; Alioğlu, Firdevs

    2013-01-01

    This study screened the prevalence and correlates of dissociative disorders among depressive women in the general population. The Dissociative Disorders Interview Schedule and the posttraumatic stress disorder (PTSD) and borderline personality disorder sections of the Structured Clinical Interview for DSM-IV were administered to 628 women in 500 homes. The prevalence of current major depressive episode was 10.0%. Of the women, 26 (40.6%) had the lifetime diagnosis of a DSM-IV, dissociative disorder, yielding a prevalence of 4.1% for dissociative depression. This group was younger (mean age = 30.7 years) than the nondissociative depression women (mean age = 39.6 years). There was no difference between the 2 groups on comorbid somatization disorder, PTSD, or borderline personality disorder. Besides suicide attempts, the dissociative group was characterized by secondary features of dissociative identity disorder; Schneiderian symptoms; borderline personality disorder criteria; and extrasensory perceptions, including possession experiences. They reported suicidality, thoughts of guilt and worthlessness, diminished concentration and indecisiveness, and appetite and weight changes more frequently than the nondissociative group. Early cessation of school education and childhood sexual abuse were frequently reported by the dissociative depression group. With its distinct features, the concept of dissociative depression may facilitate understanding of treatment resistance in, development of better psychotherapy strategies for, and new thinking on the neurobiology and pharmacotherapy of depressive disorders.

  15. Determination of enzyme-substrate dissociation rates by dynamic isotope exchange enhancement experiments

    International Nuclear Information System (INIS)

    Kim, S.C.; Raushel, F.M.

    1986-01-01

    A new method for the determination of dissociation rates of enzyme-substrate complexes has been developed. The rate of exchange of a labeled product back into the substrate is measured during catalysis of the forward reaction when the forward reaction is kept far from equilibrium by the enzymatic removal of the nonexchanging product. The ratio of the exchange rate and the net rate for product formation is then determined at various concentrations of the exchanging product. A plot of this ratio is a diagnostic indication of the kinetic mechanism and the relative rates of product dissociation from the binary and ternary enzyme complexes. This technique has been applied to the reaction catalyzed by bovine liver argininosuccinate lyase. The ratio for the rate of exchange of fumarate into argininosuccinate and the net rate for product formation was found to increase with the concentration of fumarate but to reach a limit of 3.3. The ratio of rates was half-maximal at 36 mM fumarate. The data have been interpreted to indicate the argininosuccinate lyase has a random kinetic mechanism. The calculated lower limit for the rate of release of arginine from the enzyme-fumarate-arginine complex is 0.35 times as fast as the Vmax in the reverse direction. The rate of release of arginine from the enzyme-arginine binary complex is 210 times faster than Vmax in the reverse direction

  16. Duality in diffraction dissociations

    International Nuclear Information System (INIS)

    Santoro, Alberto.

    1977-01-01

    Diffractive dissociations (aN→a*πN) are naturally explained and a model that accounts for the three-variable correlation (mass-transfer-Jackson angle correlation) is presented. This model takes into account the three possible exchanges: t (pion), u(a*) and s(a) channel exchanger. The physical consequences of the model are: a strong mass-slope correlation due to the zeros of the amplitude, a factorization of diffractive dissociations (factorization of the Pomeron), the possibility of extending this model to double diffractive dissociation and diffraction by nuclei. This model was applied to the NN→NπN reaction. Using the usual parameters of the Deck model, a comparison is made with experiments for all available distributions. the strong slope of the peak at 1400 MeV is naturally explained [fr

  17. Dissociative Functions in the Normal Mourning Process.

    Science.gov (United States)

    Kauffman, Jeffrey

    1994-01-01

    Sees dissociative functions in mourning process as occurring in conjunction with integrative trends. Considers initial shock reaction in mourning as model of normal dissociation in mourning process. Dissociation is understood to be related to traumatic significance of death in human consciousness. Discerns four psychological categories of…

  18. Multicharged Ion-induced simple molecule fragmentation dynamics

    International Nuclear Information System (INIS)

    Tarisien, M.

    2003-10-01

    The aim of this work is to study the dynamics of swift multicharged ion-induced fragmentation of diatomic (CO) and triatomic (CO 2 ) molecules. Performed at the GANIL facility, this study used the Recoil Ion Momentum Spectroscopy technique (RIMS), which consists of a time-of-flight mass spectrometer, coupled with a multi-hit capability position sensitive detector (delay line anode). The high-resolution measurement of the kinetic energy distribution released (KER) during the CO fragmentation points out the limitation of the Coulomb Explosion Model, revealing, for example, the di-cation CO 2 + electronic state contribution in the case of C + /O + fragmentation pathway. Furthermore, the multi-ionization cross section dependence with the orientation of the internuclear axis of CO is compared with a geometrical model calculation. Finally, different behaviours are observed for the dissociation dynamics of a triatomic molecule (CO 2 ). While triple ionization leads mainly to a synchronous concerted fragmentation dynamics, a weak fraction of dissociating molecule follows a sequential dynamics involving CO 2 + metastable states. In the case of double ionization, (CO 2 ) 2+ di-cation dissociation dynamics is asynchronously concerted and has been interpreted using a simple model involving an asymmetrical vibration of the molecule. (author)

  19. Correlations in the hadronic double diffractive dissociation

    International Nuclear Information System (INIS)

    Goldegol, Alexandre.

    1991-05-01

    A given reaction of double diffractive dissociation is studied based on the three-component Deck Model. The correlations among the diffractive slope, the effective mass of the dissociated particle sub-system and the dissociation angle in the Gottfried-Jackson are studied based in this model. 9 refs, 19 figs

  20. Malingering dissociative identity disorder: objective and projective assessment.

    Science.gov (United States)

    Labott, Susan M; Wallach, Heather R

    2002-04-01

    Verification of dissociative identity disorder presents challenges given the complex nature of the illness. This study addressed the concern that this disorder can be successfully malingered on objective and projective psychological tests. 50 undergraduate women were assigned to a Malingering or a Control condition, then completed the Rorschach Inkblot Test and the Dissociative Experiences Scale II. The Malingering group were asked to simulate dissociative identity disorder; controls received instructions to answer all materials honestly. Analysis indicated that malingerers were significantly more likely to endorse dissociative experiences on the Dissociative Experiences Scale II in the range common to patients with diagnosed dissociative identity disorder. However, on the Rorschach there were no significant differences between the two groups. Results suggest that the assessment of dissociative identity disorder requires a multifaceted approach with both objective and projective assessment tools. Research is needed to assess these issues in clinical populations.

  1. Isotope separation by photoselective dissociative electron

    International Nuclear Information System (INIS)

    Stevens, C.G.

    1978-01-01

    A method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule is described. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, 235 UF 6 is separated from a UF 6 mixture by selective excitation followed by dissociative electron capture into 235 UF 5 - and F

  2. The dissociation of vibrationally excited CH3OSO radicals and their photolytic precursor, methoxysulfinyl chloride.

    Science.gov (United States)

    Alligood, Bridget W; Womack, Caroline C; Straus, Daniel B; Blase, Frances R; Butler, Laurie J

    2011-05-21

    The dissociation dynamics of methoxysulfinyl radicals generated from the photodissociation of CH(3)OS(O)Cl at 248 nm is investigated using both a crossed laser-molecular beam scattering apparatus and a velocity map imaging apparatus. There is evidence of only a single photodissociation channel of the precursor: S-Cl fission to produce Cl atoms and CH(3)OSO radicals. Some of the vibrationally excited CH(3)OSO radicals undergo subsequent dissociation to CH(3) + SO(2). The velocities of the detected CH(3) and SO(2) products show that the dissociation occurs via a transition state having a substantial barrier beyond the endoergicity; appropriately, the distribution of velocities imparted to these momentum-matched products is fit by a broad recoil kinetic energy distribution extending out to 24 kcal/mol in translational energy. Using 200 eV electron bombardment detection, we also detect the CH(3)OSO radicals that have too little internal energy to dissociate. These radicals are observed both at the parent CH(3)OSO(+) ion as well as at the CH(3)(+) and SO(2)(+) daughter ions; they are distinguished by virtue of the velocity imparted in the original photolytic step. The detected velocities of the stable radicals are roughly consistent with the calculated barriers (both at the CCSD(T) and G3B3 levels of theory) for the dissociation of CH(3)OSO to CH(3) + SO(2) when we account for the partitioning of internal energy between rotation and vibration as the CH(3)OSOCl precursor dissociates. © 2011 American Institute of Physics.

  3. Dissociative Spectrum Disorders in the Primary Care Setting

    OpenAIRE

    Elmore, James L.

    2000-01-01

    Dissociative disorders have a lifetime prevalence of about 10%. Dissociative symptoms may occur in acute stress disorder, posttraumatic stress disorder, somatization disorder, substance abuse, trance and possession trance, Ganser's syndrome, and dissociative identity disorder, as well as in mood disorders, psychoses, and personality disorders. Dissociative symptoms and disorders are observed frequently among patients attending our rural South Carolina community mental health center. Given the...

  4. Posterior α EEG Dynamics Dissociate Current from Future Goals in Working Memory-Guided Visual Search

    NARCIS (Netherlands)

    de Vries, I.E.J.; van Driel, J.; Olivers, C.N.L.

    2017-01-01

    Current models of visual search assume that search is guided by an active visual working memory representation of what we are currently looking for. This attentional template for currently relevant stimuli can be dissociated from accessory memory representations that are only needed prospectively,

  5. Rate coefficients for dissociative attachment and resonant electron-impact dissociation involving vibrationally excited O{sub 2} molecules

    Energy Technology Data Exchange (ETDEWEB)

    Laporta, V. [Istituto di Metodologie Inorganiche e dei Plasmi, CNR, Bari, Italy and Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Celiberto, R. [Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica, Politecnico di Bari, Italy and Istituto di Metodologie Inorganiche e dei Plasmi, CNR, Bari (Italy); Tennyson, J. [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)

    2014-12-09

    Rate coefficients for dissociative electron attachment and electron-impact dissociation processes, involving vibrationally excited molecular oxygen, are presented. Analytical fits of the calculated numerical data, useful in the applications, are also provided.

  6. Hypnotic suggestibility, cognitive inhibition, and dissociation.

    Science.gov (United States)

    Dienes, Zoltán; Brown, Elizabeth; Hutton, Sam; Kirsch, Irving; Mazzoni, Giuliana; Wright, Daniel B

    2009-12-01

    We examined two potential correlates of hypnotic suggestibility: dissociation and cognitive inhibition. Dissociation is the foundation of two of the major theories of hypnosis and other theories commonly postulate that hypnotic responding is a result of attentional abilities (including inhibition). Participants were administered the Waterloo-Stanford Group Scale of Hypnotic Susceptibility, Form C. Under the guise of an unrelated study, 180 of these participants also completed: a version of the Dissociative Experiences Scale that is normally distributed in non-clinical populations; a latent inhibition task, a spatial negative priming task, and a memory task designed to measure negative priming. The data ruled out even moderate correlations between hypnotic suggestibility and all the measures of dissociation and cognitive inhibition overall, though they also indicated gender differences. The results are a challenge for existing theories of hypnosis.

  7. Dissociation, shame, complex PTSD, child maltreatment and intimate relationship self-concept in dissociative disorder, chronic PTSD and mixed psychiatric groups.

    Science.gov (United States)

    Dorahy, Martin J; Middleton, Warwick; Seager, Lenaire; McGurrin, Patrick; Williams, Mary; Chambers, Ron

    2015-02-01

    Whilst a growing body of research has examined dissociation and other psychiatric symptoms in severe dissociative disorders (DDs), there has been no systematic examination of shame and sense of self in relationships in DDs. Chronic child abuse often associated with severe DDs, like dissociative identity disorder, is likely to heighten shame and relationship concerns. This study investigated complex posttraumatic stress disorder (PTSD), borderline and Schneiderian symptoms, dissociation, shame, child abuse, and various markers of self in relationships (e.g., relationship esteem, relationship depression, fear of relationships). Participants were assessed via clinical interview with psychometrically sound questionnaires. They fell into three diagnostic groups, dissociative disorder (n=39; primarily dissociative identity disorder), chronic PTSD (Chr-PTSD; n=13) or mixed psychiatric presentations (MP; n=21; primarily mood and anxiety disorders). All participants had a history of child abuse and/or neglect, and the groups did not differ on age and gender. The DD group was higher on nearly all measured variables than the MP group, and had more severe dissociative, borderline and Schneiderian symptoms than the Chr-PTSD sample. Shame and complex PTSD symptoms fell marginally short of predicting reductions in relationship esteem, pathological dissociative symptoms predicted increased relationship depression, and complex PTSD symptoms predicted fear of relationships. The representativeness of the samples was unknown. Severe psychiatric symptoms differentiate DDs from chronic PTSD, while dissociation and shame have a meaningful impact on specific markers of relationship functioning in psychiatric patients with a history of child abuse and neglect. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Mirror Writing and a Dissociative Identity Disorder

    Directory of Open Access Journals (Sweden)

    Catherine Le

    2009-01-01

    Full Text Available Individuals with dissociative identity disorder (DID have been known to show varied skills and talents as they change from one dissociative state to another. For example, case reports have described people who have changed their handedness or have spoken foreign languages during their dissociative states. During an interview with a patient with DID, a surprising talent emerged when she wrote a sentence for the Folstein Mini-Mental State Exam—mirror writing. It is not known whether her mirror writing had a deeper level of meaning; however, it does emphasize the idiosyncratic nature of dissociative identity disorder.

  9. Mirror writing and a dissociative identity disorder.

    Science.gov (United States)

    Le, Catherine; Smith, Joyce; Cohen, Lewis

    2009-01-01

    Individuals with dissociative identity disorder (DID) have been known to show varied skills and talents as they change from one dissociative state to another. For example, case reports have described people who have changed their handedness or have spoken foreign languages during their dissociative states. During an interview with a patient with DID, a surprising talent emerged when she wrote a sentence for the Folstein Mini-Mental State Exam-mirror writing. It is not known whether her mirror writing had a deeper level of meaning; however, it does emphasize the idiosyncratic nature of dissociative identity disorder.

  10. Study of SI engine fueled with methanol vapor and dissociation gas based on exhaust heat dissociating methanol

    International Nuclear Information System (INIS)

    Fu, Jianqin; Deng, Banglin; Liu, Jingping; Wang, Linjun; Xu, Zhengxin; Yang, Jing; Shu, Gequn

    2014-01-01

    Highlights: • The full load power decreases successively from gasoline engine, methanol vapor engine to dissociated methanol engine. • Both power and thermal efficiency of dissociated methanol engine can be improved by boosting pressure. • The conversion efficiency of recovered exhaust gas energy is largely influenced by the BMEP. • At the same BMEP, dissociated methanol engine has higher thermal efficiency than methanol vapor engine and gasoline engine. - Abstract: To improve the fuel efficiency of internal combustion (IC) engine and also achieve the goal of direct usage of methanol fuel on IC engine, an approach of exhaust heat dissociating methanol was investigated, which is a kind of method for IC engine exhaust heat recovery (EHR). A bottom cycle system is coupled with the IC engine exhaust system, which uses the exhaust heat to evaporate and dissociate methanol in its catalytic cracker. The methanol dissociation gas (including methanol vapor) is used as the fuel for IC engine. This approach was applied to both naturally aspirated (NA) engine and turbocharged engine, and the engine performance parameters were predicted by the software GT-power under various kinds of operating conditions. The improvement to IC engine performance and the conversion efficiency of recovered exhaust gas energy can be evaluated by comparing the performances of IC engine fueled with various kinds of fuels (or their compositions). Results show that, from gasoline engine, methanol vapor engine to dissociated methanol engine, the full load power decreases successively in the entire speed area due to the declining of volumetric efficiency, while it is contrary in the thermal efficiency at the same brake mean effective pressure (BMEP) level because of the improving of fuel heating value. With the increase of BMEP, the conversion efficiency of recovered exhaust gas energy is promoted. All those results indicate that the approach of exhaust heat dissociating methanol has large

  11. Dissociative recombination of the weakly bound NO-dimer cation: Cross sections and three-body dynamics

    NARCIS (Netherlands)

    Petrignani, A.; Andersson, P.U.; Pettersson, J.B.C.; Thomas, R.; Hellberg, F.; Ehlerding, A.; Larsson, M.; Zande, W.J. van der

    2005-01-01

    Dissociative recombination (DR) of the dimer ion (NO)(2)(+) has been studied at the heavy-ion storage ring CRYRING at the Manne Siegbahn Laboratory, Stockholm. The experiments were aimed at determining details on the strongly enhanced thermal rate coefficient for the dimer, interpreting the

  12. [Dissociative disorders: from Janet to DSM-IV].

    Science.gov (United States)

    Nakatani, Y

    2000-01-01

    I reviewed the literature on dissociation and dissociative disorders from Pierre Janet to DSM-IV, and examined the current trends in research. Janet's theory on hysteria is multifaceted, and is based on three psychological models. Based on a hierarchical model, Janet related hysteric symptoms to the activities within the lower strata of mental hierarchy (automatisms psychologiques), which were demonstrably shown in somnambulism. A second model was based on the concept of a psychological system, which was hypothetically composed of ideas, images, feelings, sensations, and movements. According to this model, dissociation of psychological functions was fundamental to the mechanism of hysteria: loss of integration was thought to engender fixed ideas (ideas fixes) and to lead to the development of a system totally isolated from the whole personality system. Janet also attempted to explain various mental disorders using an economic model. He referred to a loss of equilibration between psychological force and psychological tension. Thus, an unexpected emotional experience was conceived to cause a consumption of reserved psychological force, which was in turn followed by exhaustion associated with hysteric symptoms. Whereas most current researchers regard Janet as the first to study psychological trauma as a principal cause of dissociation, I feel it is important to note that he also emphasized the role of stigmata, i.e., permanent traits of hysteric patients, which were represented as a suggestibility and a tendency toward a narrowing of the consciousness field. Discussion about dissociation and its relation to trauma all but disappeared after Janet. However, during the Second World War and post-war period, some psychiatrists began to pay attention to two emerging phenomena: a high incidence of dissociative symptoms such as fugue and amnesia among combatants, and traumatic neurosis frequently observed among ex-inmates of concentration camps. In the 1970s, interest in

  13. Rate coefficients for low-energy electron dissociative attachment to molecular hydrogen

    International Nuclear Information System (INIS)

    Horacek, J.; Houfek, K.; Cizek, M.; Murakami, I.; Kato, T.

    2003-02-01

    Calculation of rate constants for dissociative electron attachment to molecular hydrogen is reported. The calculation is based on an improved nonlocal resonance model of Cizek, Horacek and Domcke which takes fully into account the nonlocality of the resonance dynamics and uses potentials with correct asymptotic forms. The rate constants are calculated for all quantum numbers v and J of the target molecules and for electron temperature in the range 0-30000 K. (author)

  14. Dynamics of NO2 dissociation. Study by resonance-enhanced multi-photon ionisation of energy distribution and of anisotropies in fragments

    International Nuclear Information System (INIS)

    Mons, Michel

    1988-01-01

    In this research thesis, the author reports the use of laser resonance-enhanced multi-photon ionization and of time-of-flight mass spectrometry for a detailed characterization of fragments produced by a photo-dissociation process. The author more particularly addressed the case of a NO 2 molecule excited at low energies above the dissociation threshold. In the first part, the author discusses issues and problems related to molecular photo-dissociation. In the second part, he presents the developed method and shows that the combined use of both techniques allows a precise characterisation of photo-fragments in terms of internal or translational energies as well as in terms of angle distributions. Finally, the author presents and discusses results obtained in the case of NO 2 [fr

  15. Approach to the unfolding and folding dynamics of add A-riboswitch upon adenine dissociation using a coarse-grained elastic network model

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chunhua [College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124 (China); Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 45108 (United States); Lv, Dashuai; Zhang, Lei; Yang, Feng; Wang, Cunxin [College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124 (China); Su, Jiguo, E-mail: jiguosu@ysu.edu.cn, E-mail: zhng@umich.edu [College of Science, Yanshan University, Qinhuangdao 066004 (China); Zhang, Yang, E-mail: jiguosu@ysu.edu.cn, E-mail: zhng@umich.edu [Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 45108 (United States)

    2016-07-07

    Riboswitches are noncoding mRNA segments that can regulate the gene expression via altering their structures in response to specific metabolite binding. We proposed a coarse-grained Gaussian network model (GNM) to examine the unfolding and folding dynamics of adenosine deaminase (add) A-riboswitch upon the adenine dissociation, in which the RNA is modeled by a nucleotide chain with interaction networks formed by connecting adjoining atomic contacts. It was shown that the adenine binding is critical to the folding of the add A-riboswitch while the removal of the ligand can result in drastic increase of the thermodynamic fluctuations especially in the junction regions between helix domains. Under the assumption that the native contacts with the highest thermodynamic fluctuations break first, the iterative GNM simulations showed that the unfolding process of the adenine-free add A-riboswitch starts with the denature of the terminal helix stem, followed by the loops and junctions involving ligand binding pocket, and then the central helix domains. Despite the simplified coarse-grained modeling, the unfolding dynamics and pathways are shown in close agreement with the results from atomic-level MD simulations and the NMR and single-molecule force spectroscopy experiments. Overall, the study demonstrates a new avenue to investigate the binding and folding dynamics of add A-riboswitch molecule which can be readily extended for other RNA molecules.

  16. Free energy landscape of dissociative adsorption of methane on ideal and defected graphene from ab initio simulations

    Science.gov (United States)

    Wlazło, M.; Majewski, J. A.

    2018-03-01

    We study the dissociative adsorption of methane at the surface of graphene. Free energy profiles, which include activation energies for different steps of the reaction, are computed from constrained ab initio molecular dynamics. At 300 K, the reaction barriers are much lower than experimental bond dissociation energies of gaseous methane, strongly indicating that the graphene surface acts as a catalyst of methane decomposition. On the other hand, the barriers are still much higher than on the nickel surface. Methane dissociation therefore occurs at a higher rate on nickel than on graphene. This reaction is a prerequisite for graphene growth from a precursor gas. Thus, the growth of the first monolayer should be a fast and efficient process while subsequent layers grow at a diminished rate and in a more controllable manner. Defects may also influence reaction energetics. This is evident from our results, in which simple defects (Stone-Wales defect and nitrogen substitution) lead to different free energy landscapes at both dissociation and adsorption steps of the process.

  17. Effect of vibrational excitation on the dynamics of ion-molecule reactions

    International Nuclear Information System (INIS)

    Anderson, S.L.

    1981-11-01

    A new experimental technique for the study of vibrational effects on ion-molecule reaction cross sections is described. Vibrational and collision energy dependent cross sections are presented for proton and H atom transfer, charge transfer and collision induced dissociation reactions in various isotopic H 2 + + H 2 systems. Charge and proton transfer cross sections are presented for the reactions of H 2 + and D 2 + with Ar, N 2 , CO, and O 2 . All the reactions are shown to be highly influenced by avoided crossings between the ground and first excited potential energy surfaces. Because of the nature of the crossings, vibrational motion of the systems can cause both adiabatic and non-adiabatic behavior of the system. This makes the vibrational dependences of the various cross sections a very sensitive probe of the dynamics of the collisions particularly, their behavior in the region of the crossings. Evidence is seen for charge transfer between reagents as they approach each other, transition to and in some cases reactions on excited potential energy surfaces, competition between different channels, and strong coupling of proton and charge transfer channels which occurs only for two of the systems studied (H 2 + + Ar, N 2 ). Oscillatory structure is observed in the collision energy dependence of the endoergic H 2 + (v = 0) + Ar charge transfer reaction for the first time, and a simple model which is commonly used for atom-atom charge transfer is used to fit the peaks. Finally a simple model is used to assess the importance of energy resonance and Franck-Condon effects on molecular charge transfer

  18. State-to-state time-of-flight measurements of NO scattering from Au(111): direct observation of translation-to-vibration coupling in electronically nonadiabatic energy transfer.

    Science.gov (United States)

    Golibrzuch, Kai; Shirhatti, Pranav R; Altschäffel, Jan; Rahinov, Igor; Auerbach, Daniel J; Wodtke, Alec M; Bartels, Christof

    2013-09-12

    Translational motion is believed to be a spectator degree of freedom in electronically nonadiabatic vibrational energy transfer between molecules and metal surfaces, but the experimental evidence available to support this view is limited. In this work, we have experimentally determined the translational inelasticity in collisions of NO molecules with a single-crystal Au(111) surface-a system with strong electronic nonadiabaticity. State-to-state molecular beam surface scattering was combined with an IR-UV double resonance scheme to obtain high-resolution time-of-flight data. The measurements include vibrationally elastic collisions (v = 3→3, 2→2) as well as collisions where one or two quanta of molecular vibration are excited (2→3, 2→4) or de-excited (2→1, 3→2, 3→1). In addition, we have carried out comprehensive measurements of the effects of rotational excitation on the translational energy of the scattered molecules. We find that under all conditions of this work, the NO molecules lose a large fraction (∼0.45) of their incidence translational energy to the surface. Those molecules that undergo vibrational excitation (relaxation) during the collision recoil slightly slower (faster) than vibrationally elastically scattered molecules. The amount of translational energy change depends on the surface temperature. The translation-to-rotation coupling, which is well-known for v = 0→0 collisions, is found to be significantly weaker for vibrationally inelastic than elastic channels. Our results clearly show that the spectator view of the translational motion in electronically nonadiabatic vibrational energy transfer between NO and Au(111) is only approximately correct.

  19. Optimal control theory for quantum-classical systems: Ehrenfest molecular dynamics based on time-dependent density-functional theory

    International Nuclear Information System (INIS)

    Castro, A; Gross, E K U

    2014-01-01

    We derive the fundamental equations of an optimal control theory for systems containing both quantum electrons and classical ions. The system is modeled with Ehrenfest dynamics, a non-adiabatic variant of molecular dynamics. The general formulation, that needs the fully correlated many-electron wavefunction, can be simplified by making use of time-dependent density-functional theory. In this case, the optimal control equations require some modifications that we will provide. The abstract general formulation is complemented with the simple example of the H 2 + molecule in the presence of a laser field. (paper)

  20. The adsorption and dissociation of water molecule on goethite (010) surface: A DFT approach

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Long, E-mail: shuweixia@ouc.edu.cn [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, College of Chemistry and Chemical Engineering (China); Xiu, Fangyuan [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, College of Chemistry and Chemical Engineering (China); Qiu, Meng [Qingdao Institute of Bioenergy and Bioprocess Technology (China); Xia, Shuwei; Yu, Liangmin [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, College of Chemistry and Chemical Engineering (China)

    2017-01-15

    Graphical abstract: The optimized structure of hydrated goethite (010) surface with medium water coverage (water density about 6.7 H{sub 2}O/nm{sup 2}). - Highlights: • Stable adsorption and dissociation structure of H{sub 2}O on goethite (010) surface was investigated by DFT. • Reasonable path for water dissociation was proposed by transitional state analysis. • The mechanism of water adsorption on goethite and binding nature were revealed by PDOS. - Abstract: Using density functional theory (DFT) calculation, we investigate the configuration, stability and electronic properties of fresh cleaved (010) goethite surface (Pnma) and this surface exposed to water monolayer at low, medium and high coverage. Water is predicted to be chemisorbed to the surface, together with the surface reconstruction. The interaction energy of the most stable configuration of both low and medium coverage per water molecule is almost the same (−1.17 eV), while that of high coverage is much lower (less than 1.03 eV). It indicates that highly hydrated surface is less stable. PDOS analysis reveals the adsorption of H{sub 2}O is due to the formation of Fe−O bond, caused by overlapping of Fe's 3d and O's 2p orbitals. Dissociation processes at low and medium water coverage are non-spontaneous; while at high coverage, it can undertake spontaneously both thermodynamically and dynamically. The dissociation paths of all three water coverage are the similar. The proton from one adsorbed water is likely to dissociate to bind to the vicinal surface μ{sub 3}−O as an intermediate product; the proton belonged to μ{sub 3}−O transferred to the neighbor surface μ{sub 2}−O as the dissociative configuration.

  1. Symmetry Breakdown in Ground State Dissociation of HD+

    International Nuclear Information System (INIS)

    Ben-Itzhak, I.; Wells, E.; Carnes, K. D.; Krishnamurthi, Vidhya; Weaver, O. L.; Esry, B. D.

    2000-01-01

    Experimental studies of the dissociation of the electronic ground state of HD + following ionization of HD by fast proton impact indicate that the H + +D 1s dissociation channel is more likely than the H1s+D + dissociation channel by about 7% . This isotopic symmetry breakdown is due to the finite nuclear mass correction to the Born-Oppenheimer approximation which makes the 1sσ state 3.7 meV lower than the 2pσ state at the dissociation limit. The measured fractions of the two dissociation channels are in agreement with coupled-channels calculations of 1sσ to 2pσ transitions. (c) 2000 The American Physical Society

  2. Assessment of dissociation in Bosnian treatment-seeking refugees in Denmark.

    Science.gov (United States)

    Palic, Sabina; Carlsson, Jessica; Armour, Cherie; Elklit, Ask

    2015-05-01

    Dissociative experiences are common in traumatized individuals, and can sometimes be mistaken for psychosis. It is difficult to identify pathological dissociation in the treatment of traumatized refugees, because there is a lack of systematic clinical descriptions of dissociative phenomena in refugees. Furthermore, we are currently unaware of how dissociation measures perform in this clinical group. To describe the phenomenology of dissociative symptoms in Bosnian treatment-seeking refugees in Denmark. As a part of a larger study, dissociation was assessed systematically in 86 Bosnian treatment-seeking refugees using a semi-structured clinical interview (Structured Interview for Disorders of Extreme Stress-dissociation subscale; SIDES-D) and a self-report scale (Dissociative Experiences Scale; DES). The SIDES-D indicated twice as high prevalence of pathological dissociation as the DES. According to the DES, 30% of the refugees had pathological dissociation 15 years after their resettlement. On the SIDES-D, depersonalization and derealization experiences were the most common. Also, questions about depersonalization and derealization at times elicited reporting of visual and perceptual hallucinations, which were unrelated to traumatic re-experiencing. Questions about personality alteration elicited spontaneous reports of a phenomenon of "split" pre- and post-war identity in the refugee group. Whether this in fact is a dissociative phenomenon, characteristic of severe traumatization in adulthood, needs further examination. Knowledge of dissociative symptoms in traumatized refugees is important in clinical settings to prevent misclassification and to better target psychotherapeutic interventions. Much development in the measurement of dissociation in refugees is needed.

  3. The Parenting Experiences of Mothers with Dissociative Disorders.

    Science.gov (United States)

    Benjamin, Lynn R.; Benjamin, Robert; Rind, Bruce

    1998-01-01

    Presents a qualitative analysis of the experience of parenting of mothers with dissociative disorders. Using the mothers' words, describes how the five symptom areas of dissociation impeded their parenting efforts. Discusses the necessity of addressing parenting in the treatment of client-mothers with dissociative disorders. (Author/MKA)

  4. Calculations of non-adiabatic couplings within equation-of-motion coupled-cluster framework: Theory, implementation, and validation against multi-reference methods

    Science.gov (United States)

    Faraji, Shirin; Matsika, Spiridoula; Krylov, Anna I.

    2018-01-01

    We report an implementation of non-adiabatic coupling (NAC) forces within the equation-of-motion coupled-cluster with single and double excitations (EOM-CCSD) framework via the summed-state approach. Using illustrative examples, we compare NAC forces computed with EOM-CCSD and multi-reference (MR) wave functions (for selected cases, we also consider configuration interaction singles). In addition to the magnitude of the NAC vectors, we analyze their direction, which is important for the calculations of the rate of non-adiabatic transitions. Our benchmark set comprises three doublet radical-cations (hexatriene, cyclohexadiene, and uracil), neutral uracil, and sodium-doped ammonia clusters. When the characters of the states agree among different methods, we observe good agreement between the respective NAC vectors, both in the Franck-Condon region and away. In the cases of large discrepancies between the methods, the disagreement can be attributed to the difference in the states' character, which, in some cases, is very sensitive to electron correlation, both within single-reference and multi-reference frameworks. The numeric results confirm that the accuracy of NAC vectors depends critically on the quality of the underlying wave functions. Within their domain of applicability, EOM-CC methods provide a viable alternative to MR approaches.

  5. Kinetics of Huperzine A Dissociation from Acetylcholinesterase via Multiple Unbinding Pathways.

    Science.gov (United States)

    Rydzewski, Jakub; Jakubowski, Rafal; Nowak, Wieslaw; Grubmüller, Helmut

    2018-05-01

    The dissociation of huperzine A (hupA) from Torpedo californica acetylcholinesterase (TcAChE) was investigated by 4-microsecond unbiased and biased all-atom molecular dynamics (MD) simulations in explicit solvent. We performed our study using memetic sampling (MS) for the determination of reaction pathways (RPs), metadynamics to calculate free energy, and maximum-likelihood estimation (MLE) to recover kinetic rates from unbiased MD simulations. Our simulations suggest that the dissociation of hupA occurs mainly via two RPs: a front-door along the axis of the active-site gorge (pwf) and through a new transient side-door (pws), i.e., formed by the Omega-loop (residues 67--94 of TcAChE). Analysis of the inhibitor unbinding along the RPs suggests that pws is opened transiently after hupA and the Omega-loop reach a low free-energy transition state characterized by the orientation of the pyridone group of the inhibitor directed toward the Omega-loop plane. Unlike pws, pwf does not require large structural changes of TcAChE to be accessible. The estimated free energies and rates agree well with available experimental data. The dissociation rates along the unbinding pathways are similar, suggesting that the dissociation of hupA along pws is likely to be relevant. This indicates that perturbations to hupA-TcAChE interactions could potentially induce pathway hopping. In summary, out results characterize the slow-onset inhibition of TcAChE by hupA, which may provide the structural and energetic basis for the rational design of the next-generation slow-onset inhibitors with optimized pharmacokinetic properties for the treatment of Alzheimer's disease.

  6. Dissociation and the Development of Psychopathology.

    Science.gov (United States)

    Putnam, Frank W.; Trickett, Penelope K.

    This paper reviews the research on dissociation and the development of psychopathology in children and adolescents. Definitions and dimensions of dissociation are addressed, noting its range from normative daydreaming to the extremes found in individuals with multiple personality disorder. Memory dysfunctions, disturbances of identity, passive…

  7. Electron Transfer Dissociation and Collision-Induced Dissociation of Underivatized Metallated Oligosaccharides

    Science.gov (United States)

    Schaller-Duke, Ranelle M.; Bogala, Mallikharjuna R.; Cassady, Carolyn J.

    2018-05-01

    Electron transfer dissociation (ETD) and collision-induced dissociation (CID) were used to investigate underivatized, metal-cationized oligosaccharides formed via electrospray ionization (ESI). Reducing and non-reducing sugars were studied including the tetrasaccharides maltotetraose, 3α,4β,3α-galactotetraose, stachyose, nystose, and a heptasaccharide, maltoheptaose. Univalent alkali, divalent alkaline earth, divalent and trivalent transition metal ions, and a boron group trivalent metal ion were adducted to the non-permethylated oligosaccharides. ESI generated [M + Met]+, [M + 2Met]2+, [M + Met]2+, [M + Met - H]+, and [M + Met - 2H]+ most intensely along with low intensity nitrate adducts, depending on the metal and sugar ionized. The ability of these metal ions to produce oligosaccharide adduct ions by ESI had the general trend: Ca(II) > Mg(II) > Ni(II) > Co(II) > Zn(II) > Cu(II) > Na(I) > K(I) > Al(III) ≈ Fe(III) ≈ Cr(III). Although trivalent metals were utilized, no triply charged ions were formed. Metal cations allowed for high ESI signal intensity without permethylation. ETD and CID on [M + Met]2+ produced various glycosidic and cross-ring cleavages, with ETD producing more cross-ring and internal ions, which are useful for structural analysis. Product ion intensities varied based on glycosidic-bond linkage and identity of monosaccharide sub-unit, and metal adducts. ETD and CID showed high fragmentation efficiency, often with complete precursor dissociation, depending on the identity of the adducted metal ion. Loss of water was occasionally observed, but elimination of small neutral molecules was not prevalent. For both ETD and CID, [M + Co]2+ produced the most uniform structurally informative dissociation with all oligosaccharides studied. The ETD and CID spectra were complementary. [Figure not available: see fulltext.

  8. Electron Transfer Dissociation and Collision-Induced Dissociation of Underivatized Metallated Oligosaccharides

    Science.gov (United States)

    Schaller-Duke, Ranelle M.; Bogala, Mallikharjuna R.; Cassady, Carolyn J.

    2018-02-01

    Electron transfer dissociation (ETD) and collision-induced dissociation (CID) were used to investigate underivatized, metal-cationized oligosaccharides formed via electrospray ionization (ESI). Reducing and non-reducing sugars were studied including the tetrasaccharides maltotetraose, 3α,4β,3α-galactotetraose, stachyose, nystose, and a heptasaccharide, maltoheptaose. Univalent alkali, divalent alkaline earth, divalent and trivalent transition metal ions, and a boron group trivalent metal ion were adducted to the non-permethylated oligosaccharides. ESI generated [M + Met]+, [M + 2Met]2+, [M + Met]2+, [M + Met - H]+, and [M + Met - 2H]+ most intensely along with low intensity nitrate adducts, depending on the metal and sugar ionized. The ability of these metal ions to produce oligosaccharide adduct ions by ESI had the general trend: Ca(II) > Mg(II) > Ni(II) > Co(II) > Zn(II) > Cu(II) > Na(I) > K(I) > Al(III) ≈ Fe(III) ≈ Cr(III). Although trivalent metals were utilized, no triply charged ions were formed. Metal cations allowed for high ESI signal intensity without permethylation. ETD and CID on [M + Met]2+ produced various glycosidic and cross-ring cleavages, with ETD producing more cross-ring and internal ions, which are useful for structural analysis. Product ion intensities varied based on glycosidic-bond linkage and identity of monosaccharide sub-unit, and metal adducts. ETD and CID showed high fragmentation efficiency, often with complete precursor dissociation, depending on the identity of the adducted metal ion. Loss of water was occasionally observed, but elimination of small neutral molecules was not prevalent. For both ETD and CID, [M + Co]2+ produced the most uniform structurally informative dissociation with all oligosaccharides studied. The ETD and CID spectra were complementary. [Figure not available: see fulltext.

  9. Dissociative identity disorder: a controversial diagnosis.

    Science.gov (United States)

    Gillig, Paulette Marie

    2009-03-01

    A brief description of the controversies surrounding the diagnosis of dissociative identity disorder is presented, followed by a discussion of the proposed similarities and differences between dissociative identity disorder and borderline personality disorder. The phenomenon of autohypnosis in the context of early childhood sexual trauma and disordered attachment is discussed, as is the meaning of alters or alternate personalities. The author describes recent neurosciences research that may relate the symptoms of dissociative identity disorder to demonstrable disordered attention and memory processes. A clinical description of a typical patient presentation is included, plus some recommendations for approaches to treatment.

  10. Assessing the structure and meaningfulness of the dissociative subtype of PTSD.

    Science.gov (United States)

    Ross, Jana; Baník, Gabriel; Dědová, Mária; Mikulášková, Gabriela; Armour, Cherie

    2018-01-01

    Studies conducted in the USA, Canada and Denmark have supported the existence of the dissociative PTSD subtype, characterized primarily by symptoms of depersonalization and derealization. The current study aimed to examine the dissociative PTSD subtype in an Eastern European, predominantly female (83.16%) sample, using an extended set of dissociative symptoms. A latent profile analysis was applied to the PTSD and dissociation data from 689 trauma-exposed university students from Slovakia. Four latent profiles of varying PTSD and dissociation symptomatology were uncovered. They were named non-symptomatic, moderate PTSD, high PTSD and dissociative PTSD. The dissociative PTSD profile showed elevations on depersonalization and derealization, but also the alternative dissociative indicators of gaps in awareness and memory, sensory misperceptions and cognitive and behavioural re-experiencing. The core PTSD symptoms of 'memory impairment' and 'reckless or self-destructive behaviour' were also significantly elevated in the dissociative PTSD profile. Moreover, anxiety and anger predicted membership in the dissociative PTSD profile. The results provide support for the proposal that the dissociative PTSD subtype can be characterized by a variety of dissociative symptoms.

  11. The Role of Electronic Excitations on Chemical Reaction Dynamics at Metal, Semiconductor and Nanoparticle Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tully, John C. [Yale Univ., New Haven, CT (United States)

    2017-06-10

    Chemical reactions are often facilitated and steered when carried out on solid surfaces, essential for applications such as heterogeneous catalysis, solar energy conversion, corrosion, materials processing, and many others. A critical factor that can determine the rates and pathways of chemical reactions at surfaces is the efficiency and specificity of energy transfer; how fast does energy move around and where does it go? For reactions on insulator surfaces energy transfer generally moves in and out of vibrations of the adsorbed molecule and the underlying substrate. By contrast, on metal surfaces, metallic nanoparticles and semiconductors, another pathway for energy flow opens up, excitation and de-excitation of electrons. This so-called “nonadiabatic” mechanism often dominates the transfer of energy and can directly impact the course of a chemical reaction. Conventional computational methods such as molecular dynamics simulation do not account for this nonadiabatic behavior. The current DOE-BES funded project has focused on developing the underlying theoretical foundation and the computational methodology for the prediction of nonadiabatic chemical reaction dynamics at surfaces. The research has successfully opened up new methodology and new applications for molecular simulation. In particular, over the last three years, the “Electronic Friction” theory, pioneered by the PI, has now been developed into a stable and accurate computational method that is sufficiently practical to allow first principles “on-the-fly” simulation of chemical reaction dynamics at metal surfaces.

  12. Dissociative electron attachment studies on acetone

    International Nuclear Information System (INIS)

    Prabhudesai, Vaibhav S.; Tadsare, Vishvesh; Ghosh, Sanat; Gope, Krishnendu; Davis, Daly; Krishnakumar, E.

    2014-01-01

    Dissociative electron attachment (DEA) to acetone is studied in terms of the absolute cross section for various fragment channels in the electron energy range of 0–20 eV. H − is found to be the most dominant fragment followed by O − and OH − with only one resonance peak between 8 and 9 eV. The DEA dynamics is studied by measuring the angular distribution and kinetic energy distribution of fragment anions using Velocity Slice Imaging technique. The kinetic energy and angular distribution of H − and O − fragments suggest a many body break-up for the lone resonance observed. The ab initio calculations show that electron is captured in the multi-centered anti-bonding molecular orbital which would lead to a many body break-up of the resonance

  13. The Many Faces of Dissociation: Opportunities for Innovative Research in Psychiatry

    Science.gov (United States)

    2014-01-01

    It has been claimed that the progress of psychiatry has lagged behind that of other medical disciplines over the last few decades. This may suggest the need for innovative thinking and research in psychiatry, which should consider neglected areas as topics of interest in light of the potential progress which might be made in this regard. This review is concerned with one such field of psychiatry: dissociation and dissociative disorders. Dissociation is the ultimate form of human response to chronic developmental stress, because patients with dissociative disorders report the highest frequency of childhood abuse and/or neglect among all psychiatric disorders. The cardinal feature of dissociation is a disruption in one or more mental functions. Dissociative amnesia, depersonalization, derealization, identity confusion, and identity alterations are core phenomena of dissociative psychopathology which constitute a single dimension characterized by a spectrum of severity. While dissociative identity disorder (DID) is the most pervasive condition of all dissociative disorders, partial representations of this spectrum may be diagnosed as dissociative amnesia (with or without fugue), depersonalization disorder, and other specified dissociative disorders such as subthreshold DID, dissociative trance disorder, acute dissociative disorders, and identity disturbances due to exposure to oppression. In addition to constituting disorders in their own right, dissociation may accompany almost every psychiatric disorder and operate as a confounding factor in general psychiatry, including neurobiological and psycho-pharmacological research. While an anti- dissociative drug does not yet exist, appropriate psychotherapy leads to considerable improvement for many patients with dissociative disorders. PMID:25598819

  14. Electron-impact-ionization dynamics of S F6

    Science.gov (United States)

    Bull, James N.; Lee, Jason W. L.; Vallance, Claire

    2017-10-01

    A detailed understanding of the dissociative electron ionization dynamics of S F6 is important in the modeling and tuning of dry-etching plasmas used in the semiconductor manufacture industry. This paper reports a crossed-beam electron ionization velocity-map imaging study on the dissociative ionization of cold S F6 molecules, providing complete, unbiased kinetic energy distributions for all significant product ions. Analysis of these distributions suggests that fragmentation following single ionization proceeds via formation of S F5 + or S F3 + ions that then dissociate in a statistical manner through loss of F atoms or F2, until most internal energy has been liberated. Similarly, formation of stable dications is consistent with initial formation of S F4 2 + ions, which then dissociate on a longer time scale. These data allow a comparison between electron ionization and photoionization dynamics, revealing similar dynamical behavior. In parallel with the ion kinetic energy distributions, the velocity-map imaging approach provides a set of partial ionization cross sections for all detected ionic fragments over an electron energy range of 50-100 eV, providing partial cross sections for S2 +, and enables the cross sections for S F4 2 + from S F+ to be resolved.

  15. Teaching Chinese psychiatrists to make reliable dissociative disorder diagnoses.

    Science.gov (United States)

    Fan, Qing; Yu, Junhan; Ross, Colin A; Keyes, Benjamin B; Dai, Yunfei; Zhang, Tianhong; Wang, Lanlan; Xiao, Zeping

    2011-09-01

    The aim of the study was to assess the outcome of an educational effort by two North American experts in dissociative disorders to teach Chinese psychiatrists to make reliable dissociative disorder diagnoses. In the final phase of the educational effort, 569 patients at Shanghai Mental Health Center completed the Chinese version of the Dissociative Experiences Scale (DES). Patients were then randomly selected in different proportions according to their DES scores: 96 selected patients were then assessed with the Dissociative Disorders Interview Schedule (DDIS) and clinical diagnostic interviews based on DSM-IV criteria. According to the clinical diagnostic interviews, 28 (4.9%) patients were diagnosed as having dissociative disorders. Agreement between the American experts and Chinese psychiatrists for presence or absence of a dissociative disorder was 0.75 using Cohen's kappa. Dissociative disorders can be diagnosed in China with good inter-rater reliability. The authors describe the steps taken to achieve this outcome.

  16. Dynamic regime of coherent population trapping and optimization of frequency modulation parameters in atomic clocks.

    Science.gov (United States)

    Yudin, V I; Taichenachev, A V; Basalaev, M Yu; Kovalenko, D V

    2017-02-06

    We theoretically investigate the dynamic regime of coherent population trapping (CPT) in the presence of frequency modulation (FM). We have formulated the criteria for quasi-stationary (adiabatic) and dynamic (non-adiabatic) responses of atomic system driven by this FM. Using the density matrix formalism for Λ system, the error signal is exactly calculated and optimized. It is shown that the optimal FM parameters correspond to the dynamic regime of atomic-field interaction, which significantly differs from conventional description of CPT resonances in the frame of quasi-stationary approach (under small modulation frequency). Obtained theoretical results are in good qualitative agreement with different experiments. Also we have found CPT-analogue of Pound-Driver-Hall regime of frequency stabilization.

  17. Frontal and occipital perfusion changes in dissociative identity disorder.

    Science.gov (United States)

    Sar, Vedat; Unal, Seher N; Ozturk, Erdinc

    2007-12-15

    The aim of the study was to investigate if there were any characteristics of regional cerebral blood flow (rCBF) in dissociative identity disorder. Twenty-one drug-free patients with dissociative identity disorder and nine healthy volunteers participated in the study. In addition to a clinical evaluation, dissociative psychopathology was assessed using the Structured Clinical Interview for DSM-IV Dissociative Disorders, the Dissociative Experiences Scale and the Clinician-Administered Dissociative States Scale. A semi-structured interview for borderline personality disorder, the Hamilton Depression Rating Scale, and the Childhood Trauma Questionnaire were also administered to all patients. Normal controls had to be without a history of childhood trauma and without any depressive or dissociative disorder. Regional cerebral blood flow (rCBF) was studied with single photon emission computed tomography (SPECT) with Tc99m-hexamethylpropylenamine (HMPAO) as a tracer. Compared with findings in the control group, the rCBF ratio was decreased among patients with dissociative identity disorder in the orbitofrontal region bilaterally. It was increased in median and superior frontal regions and occipital regions bilaterally. There was no significant correlation between rCBF ratios of the regions of interest and any of the psychopathology scale scores. An explanation for the neurophysiology of dissociative psychopathology has to invoke a comprehensive model of interaction between anterior and posterior brain regions.

  18. Time resolved studies of H2+ dissociation with phase-stabilized laser pulses

    International Nuclear Information System (INIS)

    Fischer, Bettina

    2010-01-01

    In the course of this thesis, experimental studies on the dissociation of H 2 + (H 2 + →p+H) in ultrashort laser pulses with a stabilized carrier-envelope phase (CEP) were carried out. In single-pulse measurements, the ability to control the emission direction of low energetic protons, i.e. the localization of the bound electron at one of the nuclei after dissociation, by the CEP was demonstrated. The coincident detection of the emitted protons and electrons and the measurement of their three-dimensional momentum vectors with a reaction microscope allowed to clarify the localization mechanism. Further control was achieved by a pump-control scheme with two timedelayed CEP-stabilized laser pulses. Here the neutral H 2 molecule was ionized in the first pulse and dissociation was induced by the second pulse. Electron localization was shown to depend on the properties of the bound nuclear wave packet in H 2 + at the time the control pulse is applied, demonstrating the ability to use the shape and dynamics of the nuclear wave packet as control parameters. Wave packet simulations were performed reproducing qualitatively the experimental results of the single and the two-pulse measurements. For both control schemes, intuitive models are presented, which qualitatively explain the main features of the obtained results. (orig.)

  19. Parents' descriptions of young children's dissociative reactions after trauma.

    Science.gov (United States)

    Cintron, Gabriela; Salloum, Alison; Blair-Andrews, Zoe; Storch, Eric A

    2017-10-09

    There is limited research on the phenomenology of how young children who have been exposed to trauma express the intrusive symptom of dissociative reactions. The current qualitative study utilized interviews from a semi-structured diagnostic clinical interview with 74 caregivers of young children (ages 3 to 7) who were exposed to trauma to identify parents' descriptions of their children's dissociative reactions during a clinical interview. Based on results from the interview, 45.9% of the children had dissociative reactions (8.5% had flashbacks and 41.9% had dissociative episodes). Interviews were transcribed to identify themes of dissociative reactions in young children. Common themes to flashbacks and dissociative episodes included being triggered, being psychologically in their own world (e.g., spaced out and shut down), and displaying visible signs (e.g., crying and screaming). For flashbacks, caregivers reported that it seemed as if the child was re-experiencing the trauma (e.g., yelling specific words and having body responses). For dissociative episodes, caregivers noted that the child not only seemed psychologically somewhere else (e.g., distant and not there) but also would be physically positioned somewhere else (e.g., sitting and not responding). Caregivers also expressed their own reactions to the child's dissociative episode due to not understanding what was occurring, and trying to interrupt the occurrences (e.g., calling out to the child). Themes, descriptions, and phrases to describe dissociative reactions in young children after trauma can be used to help parents and professionals more accurately identify occurrences of dissociative reactions.

  20. Mirror Writing and a Dissociative Identity Disorder

    OpenAIRE

    Le, Catherine; Smith, Joyce; Cohen, Lewis

    2009-01-01

    Individuals with dissociative identity disorder (DID) have been known to show varied skills and talents as they change from one dissociative state to another. For example, case reports have described people who have changed their handedness or have spoken foreign languages during their dissociative states. During an interview with a patient with DID, a surprising talent emerged when she wrote a sentence for the Folstein Mini-Mental State Exam—mirror writing. It is not known whether her mirror...

  1. Dissociative features in posttraumatic stress disorder: A latent profile analysis.

    Science.gov (United States)

    Műllerová, Jana; Hansen, Maj; Contractor, Ateka A; Elhai, Jon D; Armour, Cherie

    2016-09-01

    The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) characterizes the dissociative subtype of posttraumatic stress disorder (PTSD) in terms of the individual meeting the criteria for PTSD and additionally reporting symptoms of depersonalization and/or derealization. The current study aimed to examine whether a dissociative PTSD profile may include alternative features of dissociation and whether it could be differentiated from a nondissociative PTSD profile on certain psychopathologies and demographics. Data from 309 trauma-exposed participants, collected through Amazon Mechanical Turk, were subjected to latent profile analysis. Regression analyses were used to examine the predictors of latent classes. Three discrete profiles named Baseline, PTSD, and Dissociative profile were uncovered. All examined features of dissociation were significantly elevated in the Dissociative profile. Anxiety, male sex, being employed, and having a minority racial background significantly predicted the Dissociative profile relative to the PTSD profile. The study points to the importance of alternative symptoms of dissociation in the dissociative PTSD subtype beyond the symptoms of depersonalization and derealization. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  2. High psychiatric comorbidity in adolescents with dissociative disorders.

    Science.gov (United States)

    Bozkurt, Hasan; Duzman Mutluer, Tuba; Kose, Cigdem; Zoroglu, Salih

    2015-06-01

    The aim of this study was to evaluate psychiatric comorbidity rates and patterns in a sample of clinically referred adolescents diagnosed with dissociative disorders (DD) by using a structured interview. All participants completed a comprehensive test battery, which consisted of a questionnaire for sociodemographic data and clinical history, Child Posttraumatic Stress Reaction Index, Childhood Abuse and Neglect Questionnaire and the Adolescent Dissociative Experiences Scale. Diagnosis was made by the Structured Clinical Interview for DSM-IV Dissociative Disorders. Psychiatric comorbidity was assessed using the Schedule for Affective Disorders and Schizophrenia for School Age Children - Present and Lifetime Version. A total of 25 adolescent subjects aged 12-18 years participated in the study. Ten adolescents were diagnosed as having dissociative identity disorder and 15 of them were diagnosed as having dissociative disorder-not otherwise specified based on the Structured Clinical Interview for DSM-IV Dissociative Disorders findings. Adolescents with dissociative identity disorder were found to have higher scores on the Adolescent Dissociative Experiences Scale and Child Posttraumatic Stress Reaction Index than the dissociative disorder-not otherwise specified group. Sexual and physical abuses were also found to be among the main traumatic events. Incest was reported in six cases of the study sample. All subjects had at least one comorbid psychiatric disorder. The most common psychiatric diagnoses were major depressive disorder (n = 25; 100%) and post-traumatic stress disorder (n = 22; 88%). High psychiatric comorbidity rates were found in adolescents diagnosed with DD. A prevalent history of abuse and traumatic events was represented. Clinicians should be aware of the impacts of DD on adolescents' mental health. © 2014 The Authors. Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology.

  3. Angular-momentum-assisted dissociation of CO in strong optical fields

    Science.gov (United States)

    Mullin, Amy; Ogden, Hannah; Murray, Matthew; Liu, Qingnan; Toro, Carlos

    2017-04-01

    Filaments are produced in CO gas by intense, chirped laser pulses. Visible emission from C2 is observed as a result of chemical reactions of highly excited CO. At laser intensities greater than 1014 W cm-2, the C2 emission shows a strong dependence on laser polarization. Oppositely chirped pulses of light with ω0 = 800 nm are recombined spatially and temporally to generate angularly accelerating electric fields (up to 30 THz) that either have an instantaneous linear polarization or act as a dynamic polarization grating that oscillates among linear and circular polarizations. The angularly accelerating linear polarization corresponds to an optical centrifuge that concurrently drives molecules into high rotational states (with J 50) and induces strong-field dissociation. Higher order excitation is observed for the time-varying laser polarization configuration that does not induce rotational excitation. The results indicate that the presence of rotational angular momentum lowers the threshold for CO dissociation in strong optical fields by coupling nuclear and electronic degrees of freedom. Support from NSF CHE-1058721 and the University of Maryland.

  4. Dynamics and Thermodynamics of Transthyretin Association from Molecular Dynamics Simulations

    Directory of Open Access Journals (Sweden)

    Cedrix J. Dongmo Foumthuim

    2018-01-01

    Full Text Available Molecular dynamics simulations are used in this work to probe the structural stability and the dynamics of engineered mutants of transthyretin (TTR, i.e., the double mutant F87M/L110M (MT-TTR and the triple mutant F87M/L110M/S117E (3M-TTR, in relation to wild-type. Free energy analysis from end-point simulations and statistical effective energy functions are used to analyze trajectories, revealing that mutations do not have major impact on protein structure but rather on protein association, shifting the equilibria towards dissociated species. The result is confirmed by the analysis of 3M-TTR which shows dissociation within the first 10 ns of the simulation, indicating that contacts are lost at the dimer-dimer interface, whereas dimers (formed by monomers which pair to form two extended β-sheets appear fairly stable. Overall the simulations provide a detailed view of the dynamics and thermodynamics of wild-type and mutant transthyretins and a rationale of the observed effects.

  5. Fast kinetics of calcium dissociation from calsequestrin

    Directory of Open Access Journals (Sweden)

    MARIANELA BELTRÁN

    2006-01-01

    Full Text Available We measured the kinetics of calcium dissociation from calsequestrin in solution or forming part of isolated junctional sarcoplasmic reticulum membranes by mixing calsequestrin equilibrated with calcium with calcium-free solutions in a stopped-flow system. In parallel, we measured the kinetics of the intrinsic fluorescence changes that take place following calcium dissociation from calsequestrin. We found that at 25ºC calcium dissociation was 10-fold faster for calsequestrin attached to junctional membranes (k = 109 s-1 than in solution. These results imply that calcium dissociation from calsequestrin in vivo is not rate limiting during excitation-contraction coupling. In addition, we found that the intrinsic fluorescence decrease for calsequestrin in solution or forming part of junctional membranes was significantly slower than the rates of calcium dissociation. The kinetics of intrinsic fluorescence changes had two components for calsequestrin associated to junctional membranes and only one for calsequestrin in solution; the faster component was 8-fold faster (k = 54.1 s-1 than the slower component (k = 6.9 s-1, which had the same k value as for calsequestrin in solution. These combined results suggest that the presence of calsequestrin at high concentrations in a restricted space, such as when bound to the junctional membrane, accelerates calcium dissociation and the resulting structural changes, presumably as a result of cooperative molecular interactions.

  6. Photochemical Dynamics of Intramolecular Singlet Fission

    Science.gov (United States)

    Lin, Zhou; Iwasaki, Hikari; Van Voorhis, Troy

    2017-06-01

    Singlet fission (SF) converts a singlet exciton (S_1) into a pair of triplet ones (T_1) via a ``multi-exciton'' (ME) intermediate: S_1 \\longleftrightarrow ^1ME \\longleftrightarrow ^1(T_1T_1) \\longrightarrow 2T_1. In exothermic cases, e.g., crystalline pentacene or its derivatives, the quantum yield of SF can reach 200%. With SF doubling the electric current generated by an incident high-energy photon, the solar conversion efficiency in pentacene-based organic photovoltaics (OPVs) can exceed the Shockley-Queisser limit of 33.7%. The ME state is popularly considered to be a dimeric state with significant charge transfer (CT) character that is strongly coupled to both S_1 and ^1(T_1T_1), while this local model lacks strong support from full quantum dynamics studies. Intramolecular SF (ISF) occurring to covalently-bound dimers in the solution phase is an excellent model for a straightforward dynamics simulation of local excitons. In the present study, we investigate the ISF mechanisms for three covalently-bound dimers of pentacene derivatives, including ortho-, meta-, and para-bis(6,13-bis(triisopropylsilylethynyl)pentacene)benzene, in non-protic solvents. Specifically, we propagate the real-time, non-adiabatic quantum mechanical/molecular mechanical (QM/MM) dynamics on the potential energy surfaces associated with the states of S_1, ^1(T_1T_1) and CT. We explore how the energies of these ISF-relevant states and the non-adiabatic couplings between each other fluctuate with time and the instantaneous molecular configuration (e.g., intermonomer distance and orientation). We also quantitatively compare Condon and non-Condon ISF dynamics with solution-phase spectroscopic data. Our results allow us to understand the roles of CT energy levels in the ISF mechanism and propose a design strategy to maximize ISF efficiency. M. B. Smith and J. Michl, Chem. Rev. 110, 6891 (2010). W. Shockley and H. J. Queisser, J. Appl. Phys. 32, 510 (1961). T. C. Berkelbach, M. S. Hybertsen

  7. Subtypes of dissociative (conversion) disorder in two tertiary hospitals in Bangladesh.

    Science.gov (United States)

    Ahsan, M S; Mullick, S I; Sobhan, M A; Khanam, M; Nahar, J S; Salam, M A; Ali, R; Islam, M; Kabir, M S

    2010-01-01

    Dissociative (conversion) disorders are common among the patients attending in and out patients of Psychiatry Department of tertiary hospitals in Bangladesh. This study was done to see the subtypes of dissociative (conversion) disorder according to International Classification of Diseases, Tenth Revision (ICD-10). This is a descriptive, cross sectional study done on 100 consecutive patients from the Departments of Psychiatry, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka and Dhaka Medical College Hospital (DMCH). Study period was July 2005 to June 2006. Among the patients of dissociative (conversion) disorder, mixed dissociative (conversion) disorder was found highest 34%, followed by dissociative convulsion 33%, dissociative motor disorders 19%, dissociative anaesthesia and sensory loss 5%, dissociative amnesia 4%, dissociative fugue 3%. However, the researcher did not find any multiple personality disorder which is relatively common in North America. This finding reflected that there are differences in prevalence of sub types of dissociative disorders in Bangladesh and Western countries.

  8. Site selective dissociation of ozone upon core excitation

    International Nuclear Information System (INIS)

    Mocellin, A.; Mundim, M.S.P.; Coutinho, L.H.; Homem, M.G.P.; Naves de Brito, A.

    2007-01-01

    We present new measurements applied to core excitation of ozone molecule using to analyze the dissociation channels the photo-electron-photo-ion coincidence (PEPICO) and the photo-electron-photo-ion-photo-ion coincidence (PEPIPICO) technique. The new experimental set-up allows measuring O + /O + ion pair coincidences without discrimination. The dissociation channels of several core-excited states have been investigated. The relative yields of dissociation channels were determined from coincidence data. The core excitation from O terminal (O T ) or O central (O C ) induce different fragmentation; preferentially one bond is broken at the O terminal excitation and two bonds when O central is excited, showing site selectivity fragmentation of ozone upon core excitation. The ultra-fast dissociation of the O T 1s -1 7a 1 1 core-excited state is confirmed by the relative yield of dissociation

  9. Trauma-Related Dissociation Is Linked With Maladaptive Personality Functioning

    Directory of Open Access Journals (Sweden)

    Antonella Granieri

    2018-05-01

    Full Text Available Background: Extensive research has demonstrated the positive associations among the exposure to traumatic experiences, the levels of dissociation, and the severity of psychiatric symptoms in adults. However, it has been hypothesized in clinical literature that an excessive activation of the dissociative processes following multiple traumatic experiences may jeopardize the psychological and behavioral functioning of the individuals, fostering higher levels of maladaptive personality functioning.Methods: The study involved 322 adult volunteers from Italy. Participants completed measures on traumatic experiences, dissociation, and maladaptive personality traits.Results: The number of traumatic experiences reported by participants were positively associated with dissociation scores and maladaptive personality scores. Mediation analyses showed that dissociation acted as a partial mediator in the relationship between traumatic experiences and overall maladaptive personality functioning. Regression curve analyses showed that the positive association between maladaptive personality functioning and dissociation was stronger among participants with higher exposure to traumatic experiences.Conclusion: Exposure to multiple traumatic experiences may increase the risk for an excessive activation of the dissociative processes, which in turn may generate severe impairments in multiple domains of personality functioning.

  10. Determination of lifetimes and nonadiabatic correlations from measured dipole polarizabilities

    International Nuclear Information System (INIS)

    Curtis, Lorenzo J

    2007-01-01

    In atomic systems for which the total oscillator strength of excitations from the ground state is dominated by the transition to the lowest resonance level, the f-sum rule provides a bracketing inequality connecting the lifetime τ of that level to the dipole polarizability α d . This relationship has been used previously to deduce α d from τ. It is shown here that improved spectroscopic accuracies now permit this procedure to be inverted, with τ deduced from a value for α d obtained spectroscopically using the core polarization model. A similar quantitative relationship exists connecting the nonadiabatic correlation factor β to τ, and thus also to α d . The method is applied to a recent measurement of α d for Kr 6+ to obtain the values τ(4s4p 1 P 1 ) 0.096 ± 0.003 ns and β(Kr 6+ ) = 1.71 ± 0.03a 5 0 . It is shown that the use of this method to make precision lifetime determinations for a small number of ions in an isoelectronic sequence permits the exploitation of observed semiempirical regularities to specify the lifetimes of all ions in that sequence

  11. Atrioventricular Dissociation after Electroconvulsive Therapy

    Directory of Open Access Journals (Sweden)

    Siegfried William Yu

    2011-01-01

    Full Text Available Electroconvulsive therapy (ECT is increasingly used as a treatment for psychiatric disorders. Cardiac effects are the principal cause of medical complications in these patients. We report a case of atrioventricular (AV dissociation that occurred after ECT that was treated with pacemaker implantation. The mechanisms contributing to the onset of AV dissociation in this patient, and the management and rationale for device therapy, in light of the most recent guidelines, are reviewed.

  12. Dissociative disorders in acute psychiatric inpatients in Taiwan.

    Science.gov (United States)

    Chiu, Chui-De; Meg Tseng, Mei-Chih; Chien, Yi-Ling; Liao, Shih-Cheng; Liu, Chih-Min; Yeh, Yei-Yu; Hwu, Hai-Gwo; Ross, Colin A

    2017-04-01

    Dissociative disorders have been documented to be common psychiatric disorders which can be detected reliably with standardized diagnostic instruments in North American and European psychiatric inpatients and outpatients (20.6% and 18.4%, respectively). However, there are concerns about their cross-cultural manifestations as an apparently low prevalence rate has been reported in East Asian inpatients and outpatients (1.7% and 4.9%, respectively). It is unknown whether the clinical profile of dissociative disorders in terms of their core symptomatic clusters, associated comorbid disorders, and environmental risk factors that has emerged in western clinical populations can also be found in non-western clinical populations. A standardized structured interview for DSM-IV dissociative disorders, post-traumatic stress disorder, and a history of interpersonal victimization was administered in a sample of Taiwanese acute psychiatric inpatients. Our results showed that 19.5% of our participants met criteria for a DSM-IV dissociative disorder, mostly dissociative disorder not otherwise specified. More importantly, the western clinical profile of dissociative disorders also characterized our patients, including a poly-symptomatic presentation and a history of interpersonal trauma in both childhood and adulthood. Our results lend support to the conclusion that cross-cultural manifestations of dissociative pathology in East Asia are similar to those in North America and Europe. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  13. Dissociative symptoms in kleptomania.

    Science.gov (United States)

    Grant, Jon E

    2004-02-01

    Many patients with kleptomania report an altered state of consciousness during acts of theft. The purpose of this investigation was to clarify a possible link between dissociation and kleptomania, a disabling disorder whose phenomenology remains understudied. 26 adult outpatients who met DSM-IV criteria for kleptoania were administered the Dissociative Experiences Scale and compared to 22 normal controls. The patients with kleptomania had scores that differed significantly from those reported by normal controls. There were no statistically significant differences by sex. Because kleptomania patients seeking treatment with medication may differ from others with kleptomania, further studies are needed.

  14. Label-Free and Real-Time Monitor of Binding and Dissociation Processes between Protein A and Swine IgG by Oblique-Incidence Reflectivity Difference Method

    International Nuclear Information System (INIS)

    He Li-Ping; Liu Shuang; Dai Jun; Lu Hui-Bin; Jin Kui-Juan; Yang Guo-Zhen; Wu Lin; Liu Guo-Zhen; Wei Han-Fu

    2015-01-01

    Life science has a need for detection methods that are label-free and real-time. In this paper, we have selected staphylococcal protein A (SPA) and swine immunoglobulin G (IgG), and monitor the bindings between SPA and swine IgG with different concentrations, as well as the dissociations of SPA-swine IgG complex in different pH values of phosphate buffer by oblique-incidence reflectivity difference (OIRD) in a label-free and real-time fashion. We obtain the ON and OFF reaction dynamic curves corresponding to the bindings and dissociations of SPA and swine IgG. Through our analysis of the experimental results, we have been able to obtain the damping coefficients and the dissociation time of SPA and swine IgG for different pH values of the phosphate buffer. The results prove that the OIRD technique is a competing method for monitoring the dynamic processes of biomolecule interaction and achieving the quantitative information of reaction kinetics. (general)

  15. Multi-mode-multi-state quantum dynamics of key five-membered heterocycles: spectroscopy and ultrafast internal conversion

    International Nuclear Information System (INIS)

    Koeppel, H.; Gromov, E.V.; Trofimov, A.B.

    2004-01-01

    The multi-mode and multi-state vibronic interactions in the heterocyclic molecules furan, pyrrole, thiophene and their radical cations are investigated theoretically, employing a linear vibronic coupling scheme. The underlying system parameters are determined from large-scale ab initio computations. Previous time-independent dynamical calculations on the radical cations are extended by wave-packet propagations (using the MCTDH method) confirming the strong nonadiabatic coupling effects. For the singlet excited states of furan and thiophene quantum dynamical calculations are presented which go beyond the two-state approximation frequently applied in the literature. The characteristic spectral structures are well reproduced, especially in the case of furan. The implications of these results on the photochemical reaction dynamics of these species are discussed

  16. A cross-cultural test of the trauma model of dissociation.

    Science.gov (United States)

    Ross, Colin A; Keyes, Benjamin B; Yan, Heqin; Wang, Zhen; Zou, Zheng; Xu, Yong; Chen, Jue; Zhang, Haiyin; Xiao, Zeping

    2008-01-01

    In order to test the trauma model of dissociation, the authors compared two samples with similar rates of reported childhood physical and sexual abuse: 502 members of the general population in Winnipeg, Canada, and 304 psychiatric outpatients at Shanghai Mental Health Center in Shanghai, China. There is virtually no popular or professional knowledge of dissociative identity disorder in China, and therefore professional and popular contamination cannot be operating. According to the trauma model, samples from different cultures with similar levels of trauma should report similar levels of dissociation. According to the sociocognitive model, in contrast, pathological dissociation is not related to trauma and should be absent in samples free of cultural and professional contamination. Of the 304 Chinese respondents, 14.5% reported childhood physical and/or sexual abuse compared to 12.5% of the Canadian sample. Both samples reported similar levels of dissociation on the Dissociative Experiences Scale and the Dissociative Disorders Interview Schedule. The findings support a specific prediction of the trauma model of dissociation not tested in previous research, and are not consistent with the sociocognitive, contamination or iatrogenic models of dissociative identity disorder.

  17. Photochemical reaction dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Moore, B.C. [Lawrence Berkeley Laboratory, Livermore, CA (United States)

    1993-12-01

    The purpose of the program is to develop a fundamental understanding of unimolecular and bimolecular reaction dynamics with application in combustion and energy systems. The energy dependence in ketene isomerization, ketene dissociation dynamics, and carbonyl substitution on organometallic rhodium complexes in liquid xenon have been studied. Future studies concerning unimolecular processes in ketene as well as energy transfer and kinetic studies of methylene radicals are discussed.

  18. The Contribution of Art Therapy to the Dissociative Disorders.

    Science.gov (United States)

    Murphy, Patricia S.

    1994-01-01

    Explored concepts of brain hemispheric lateralization and distinct right brain functioning in extensive dissociation by administering Dissociative Experiences Scale to 114 engineering students and 92 university drawing students. Chi-square calculation found differences in dissociative scoring levels between groups that approached significance at…

  19. Dissociation From a Cross-Cultural Perspective: Implications of Studies in Brazil.

    Science.gov (United States)

    Maraldi, Everton de Oliveira; Krippner, Stanley; Barros, Maria Cristina Monteiro; Cunha, Alexandre

    2017-07-01

    A major issue in the study of dissociation concerns the cross-cultural validity of definitions and measurements used to identify and classify dissociative disorders. There is also extensive debate on the etiological factors underlying dissociative experiences. Cross-cultural research is essential to elucidate these issues, particularly regarding evidence obtained from countries in which the study of dissociation is still in its infancy. The aim of this article was to discuss Brazilian research on the topic of dissociation, highlighting its contributions for the understanding of dissociative experiences in nonclinical populations and for the validity and relevance of dissociative disorders in the contexts of psychiatry, psychology, and psychotherapy. We also consider the ways in which dissociative experiences are assimilated by Brazilian culture and religious expressions, and the implications of Brazilian studies for the sociocultural investigation of dissociation. We conclude by addressing the limitations of these studies and potential areas for future research.

  20. Site selective dissociation of ozone upon core excitation

    Energy Technology Data Exchange (ETDEWEB)

    Mocellin, A. [Instituto de Fisica, Universidade de Brasilia-UnB, Box 04455, CEP 70919-970, Brasilia-DF (Brazil)], E-mail: mocellin@fis.unb.br; Mundim, M.S.P. [Instituto de Fisica, Universidade de Brasilia-UnB, Box 04455, CEP 70919-970, Brasilia-DF (Brazil); Coutinho, L.H. [Instituto de Quimica, Universidade Federal do Rio de Janeiro-UFRJ, Box 68563, CEP 21945-970, Rio de Janeiro-RJ (Brazil); Homem, M.G.P. [Laboratorio Nacional de Luz Sincrotron-LNLS, Box 6192, CEP 13084-971, Campinas-SP (Brazil); Naves de Brito, A. [Laboratorio Nacional de Luz Sincrotron-LNLS, Box 6192, CEP 13084-971, Campinas-SP (Brazil); Instituto de Fisica, Universidade de Brasilia-UnB, Box 04455, CEP 70919-970, Brasilia-DF (Brazil)

    2007-05-15

    We present new measurements applied to core excitation of ozone molecule using to analyze the dissociation channels the photo-electron-photo-ion coincidence (PEPICO) and the photo-electron-photo-ion-photo-ion coincidence (PEPIPICO) technique. The new experimental set-up allows measuring O{sup +}/O{sup +} ion pair coincidences without discrimination. The dissociation channels of several core-excited states have been investigated. The relative yields of dissociation channels were determined from coincidence data. The core excitation from O terminal (O{sub T}) or O central (O{sub C}) induce different fragmentation; preferentially one bond is broken at the O terminal excitation and two bonds when O central is excited, showing site selectivity fragmentation of ozone upon core excitation. The ultra-fast dissociation of the O{sub T} 1s{sup -1}7a{sub 1}{sup 1} core-excited state is confirmed by the relative yield of dissociation.

  1. Dissociations between developmental dyslexias and attention deficits

    Science.gov (United States)

    Lukov, Limor; Friedmann, Naama; Shalev, Lilach; Khentov-Kraus, Lilach; Shalev, Nir; Lorber, Rakefet; Guggenheim, Revital

    2014-01-01

    We examine whether attention deficits underlie developmental dyslexia, or certain types of dyslexia, by presenting double dissociations between the two. We took into account the existence of distinct types of dyslexia and of attention deficits, and focused on dyslexias that may be thought to have an attentional basis: letter position dyslexia (LPD), in which letters migrate within words, attentional dyslexia (AD), in which letters migrate between words, neglect dyslexia, in which letters on one side of the word are omitted or substituted, and surface dyslexia, in which words are read via the sublexical route. We tested 110 children and adults with developmental dyslexia and/or attention deficits, using extensive batteries of reading and attention. For each participant, the existence of dyslexia and the dyslexia type were tested using reading tests that included stimuli sensitive to the various dyslexia types. Attention deficit and its type was established through attention tasks assessing sustained, selective, orienting, and executive attention functioning. Using this procedure, we identified 55 participants who showed a double dissociation between reading and attention: 28 had dyslexia with normal attention and 27 had attention deficits with normal reading. Importantly, each dyslexia with suspected attentional basis dissociated from attention: we found 21 individuals with LPD, 13 AD, 2 neglect dyslexia, and 12 surface dyslexia without attention deficits. Other dyslexia types (vowel dyslexia, phonological dyslexia, visual dyslexia) also dissociated from attention deficits. Examination of 55 additional individuals with both a specific dyslexia and a certain attention deficit found no attention function that was consistently linked with any dyslexia type. Specifically, LPD and AD dissociated from selective attention, neglect dyslexia dissociated from orienting, and surface dyslexia dissociated from sustained and executive attention. These results indicate that

  2. Nonadiabatic effects in the Quantum Hall regime

    International Nuclear Information System (INIS)

    Page, D.A.; Brown, E.

    1993-01-01

    The authors consider the effect of a finite electric field on the states of a Bloch electron in two dimensions, with a uniform magnetic field present. They make use of the concept of electric time translation symmetry and treat the electric and magnetic fields symmetrically in a time dependent formalism. In addition to a wave vector k, the states are characterized by a frequency specifying the behavior under electric time translations. An effective Hamiltonian is employed to obtain the splitting of an isolated Bloch band into open-quotes frequencyclose quotes subbands. The time-averaged velocity and energy of the states are expressed in terms of the frequency dispersion. The relationship to the Stark ladder eigenstates in a scalar potential representation of the electric field is examined. This is seen to justify the use of the averaged energy in determining occupation of the states. In the weak electric field (adiabatic) limit, an expression is recovered for the quantized Hall conductivity of a magnetic subband as a topological invariant. A numerical procedure is outlined and results obtained over a range of electric field strengths. A transition between strong and weak field regimes is seen, with level repulsions between the frequencies playing an important role. The numerical results show how the magnetic subband structure and quantized Hall conductivity emerge as the electric field becomes weaker. In this regime, the behavior can be understood by comparison to the predictions of the adiabatic approximation. The latter predicts crossings in the frequencies at certain locations in wave vector space. Nonadiabatic effects are seen to produce gaps in the frequency spectrum at these locations. 35 refs., 14 figs

  3. Dissociative electron attachment studies on acetone

    Energy Technology Data Exchange (ETDEWEB)

    Prabhudesai, Vaibhav S., E-mail: vaibhav@tifr.res.in; Tadsare, Vishvesh; Ghosh, Sanat; Gope, Krishnendu; Davis, Daly; Krishnakumar, E. [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India)

    2014-10-28

    Dissociative electron attachment (DEA) to acetone is studied in terms of the absolute cross section for various fragment channels in the electron energy range of 0–20 eV. H{sup −} is found to be the most dominant fragment followed by O{sup −} and OH{sup −} with only one resonance peak between 8 and 9 eV. The DEA dynamics is studied by measuring the angular distribution and kinetic energy distribution of fragment anions using Velocity Slice Imaging technique. The kinetic energy and angular distribution of H{sup −} and O{sup −} fragments suggest a many body break-up for the lone resonance observed. The ab initio calculations show that electron is captured in the multi-centered anti-bonding molecular orbital which would lead to a many body break-up of the resonance.

  4. The DSM-5 dissociative-PTSD subtype: can levels of depression, anxiety, hostility, and sleeping difficulties differentiate between dissociative-PTSD and PTSD in rape and sexual assault victims?

    Science.gov (United States)

    Armour, Cherie; Elklit, Ask; Lauterbach, Dean; Elhai, Jon D

    2014-05-01

    The DSM-5 currently includes a dissociative-PTSD subtype within its nomenclature. Several studies have confirmed the dissociative-PTSD subtype in both American Veteran and American civilian samples. Studies have begun to assess specific factors which differentiate between dissociative vs. non-dissociative PTSD. The current study takes a novel approach to investigating the presence of a dissociative-PTSD subtype in its use of European victims of sexual assault and rape (N=351). Utilizing Latent Profile Analyses, we hypothesized that a discrete group of individuals would represent a dissociative-PTSD subtype. We additionally hypothesized that levels of depression, anger, hostility, and sleeping difficulties would differentiate dissociative-PTSD from a similarly severe form of PTSD in the absence of dissociation. Results concluded that there were four discrete groups termed baseline, moderate PTSD, high PTSD, and dissociative-PTSD. The dissociative-PTSD group encompassed 13.1% of the sample and evidenced significantly higher mean scores on measures of depression, anxiety, hostility, and sleeping difficulties. Implications are discussed in relation to both treatment planning and the newly published DSM-5. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Dissociation: adjustment or distress? Dissociative phenomena, absorption and quality of life among Israeli women who practice channeling compared to women with similar traumatic history.

    Science.gov (United States)

    Stolovy, Tali; Lev-Wiesel, Rachel; Witztum, Eliezer

    2015-06-01

    This study aimed to explore the relationship between traumatic history, dissociative phenomena, absorption and quality of life among a population of channelers, in comparison with a population of non-channelers with similar traumatic history. The study sample included 150 women. The measures included Traumatic Experiences Scale, Dissociative Experience Scale, Absorption Scale, Brief Symptom Inventory and Quality of Life (QOL) Assessment. Channelers presented significantly higher levels of dissociation, absorption and psychological health compared to the other group. Dissociation and absorption were trauma-related only among the comparison group. Hence, dissociation has different qualities among different people, and spiritual practice contributes to QOL.

  6. Dissociation energy of the ground state of NaH

    International Nuclear Information System (INIS)

    Huang, Hsien-Yu; Lu, Tsai-Lien; Whang, Thou-Jen; Chang, Yung-Yung; Tsai, Chin-Chun

    2010-01-01

    The dissociation energy of the ground state of NaH was determined by analyzing the observed near dissociation rovibrational levels. These levels were reached by stimulated emission pumping and fluorescence depletion spectroscopy. A total of 114 rovibrational levels in the ranges 9≤v '' ≤21 and 1≤J '' ≤14 were assigned to the X 1 Σ + state of NaH. The highest vibrational level observed was only about 40 cm -1 from the dissociation limit in the ground state. One quasibound state, above the dissociation limit and confined by the centrifugal barrier, was observed. Determining the vibrational quantum number at dissociation v D from the highest four vibrational levels yielded the dissociation energy D e =15 815±5 cm -1 . Based on new observations and available data, a set of Dunham coefficients and the rotationless Rydberg-Klein-Rees curve were constructed. The effective potential curve and the quasibound states were discussed.

  7. Abnormal Hippocampal Morphology in Dissociative Identity Disorder and Post-Traumatic Stress Disorder Correlates with Childhood Trauma and Dissociative Symptoms

    NARCIS (Netherlands)

    Chalavi, Sima; Vissia, Eline M.; Giesen, Mechteld E.; Nijenhuis, Ellert R. S.; Draijer, Nel; Cole, James H.; Dazzan, Paola; Pariante, Carmine M.; Madsen, Sarah K.; Rajagopalan, Priya; Thompson, Paul M.; Toga, Arthur W.; Veltman, Dick J.; Reinders, Antje A. T. S.

    Smaller hippocampal volume has been reported in individuals with post-traumatic stress disorder (PTSD) and dissociative identity disorder (DID), but the regional specificity of hippocampal volume reductions and the association with severity of dissociative symptoms and/or childhood traumatization

  8. Abnormal Hippocampal Morphology in Dissociative Identity Disorder and Post-Traumatic Stress Disorder Correlates with Childhood Trauma and Dissociative Symptoms

    NARCIS (Netherlands)

    Chalavi, S.; Vissia, E.M.; Giesen, M.E.; Nijenhuis, E.R.S.; Draijer, N.; Cole, J.H.; Dazzan, P.; Pariante, C.M.; Madsen, S.K.; Rajagopalan, P.; Thompson, P.M.; Toga, A.W.; Veltman, D.J.; Reinders, A.A.T.S

    2015-01-01

    Smaller hippocampal volume has been reported in individuals with post-traumatic stress disorder (PTSD) and dissociative identity disorder (DID), but the regional specificity of hippocampal volume reductions and the association with severity of dissociative symptoms and/or childhood traumatization

  9. Diffraction dissociation at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Jenkovszky, Laszlo [Bogolyubov Institute for Theoretical Physics (BITP), Ukrainian National Academy of Sciences 14-b, Metrolohichna str., Kiev, 03680, Ukraine and Wigner Research Centre for Physics, Hungarian Academy of Sciences 1525 Budapest, POB 49 (Hungary); Orava, Risto [Institute of Physics, Division of Elementary Particle Physics, P.O. Box 64 (Gustaf Haellstroeminkatu 2a), FI-00014 University of Helsinki, Finland and CERN, CH-1211 Geneva 23 (Switzerland); Salii, Andrii [Bogolyubov Institute for Theoretical Physics (BITP), Ukrainian National Academy of Sciences 14-b, Metrolohichna str., Kiev, 03680 (Ukraine)

    2013-04-15

    We report on recent calculations of low missing mass single (SD) and double (DD) diffractive dissociation at LHC energies. The calculations are based on a dual-Regge model, dominated by a single Pomeron exchange. The diffractively excited states lie on the nucleon trajectory N*, appended by the isolated Roper resonance. Detailed predictions for the squared momentum transfer and missing mass dependence of the differential and integrated single-and double diffraction dissociation in the kinematical range of present and future LHC measurements are given.

  10. Diffraction dissociation at the LHC

    International Nuclear Information System (INIS)

    Jenkovszky, László; Orava, Risto; Salii, Andrii

    2013-01-01

    We report on recent calculations of low missing mass single (SD) and double (DD) diffractive dissociation at LHC energies. The calculations are based on a dual-Regge model, dominated by a single Pomeron exchange. The diffractively excited states lie on the nucleon trajectory N*, appended by the isolated Roper resonance. Detailed predictions for the squared momentum transfer and missing mass dependence of the differential and integrated single-and double diffraction dissociation in the kinematical range of present and future LHC measurements are given.

  11. Pulsed IR Heating Studies of Single-Molecule DNA Duplex Dissociation Kinetics and Thermodynamics

    Science.gov (United States)

    Holmstrom, Erik D.; Dupuis, Nicholas F.; Nesbitt, David J.

    2014-01-01

    Single-molecule fluorescence spectroscopy is a powerful technique that makes it possible to observe the conformational dynamics associated with biomolecular processes. The addition of precise temperature control to these experiments can yield valuable thermodynamic information about equilibrium and kinetic rate constants. To accomplish this, we have developed a microscopy technique based on infrared laser overtone/combination band absorption to heat small (≈10−11 liter) volumes of water. Detailed experimental characterization of this technique reveals three major advantages over conventional stage heating methods: 1), a larger range of steady-state temperatures (20–100°C); 2), substantially superior spatial (≤20 μm) control; and 3), substantially superior temporal (≈1 ms) control. The flexibility and breadth of this spatial and temporally resolved laser-heating approach is demonstrated in single-molecule fluorescence assays designed to probe the dissociation of a 21 bp DNA duplex. These studies are used to support a kinetic model based on nucleic acid end fraying that describes dissociation for both short (10 bp) DNA duplexes. These measurements have been extended to explore temperature-dependent kinetics for the 21 bp construct, which permit determination of single-molecule activation enthalpies and entropies for DNA duplex dissociation. PMID:24411254

  12. Ab initio/interpolated quantum dynamics on coupled electronic states with full configuration interaction wave functions

    International Nuclear Information System (INIS)

    Thompson, K.; Martinez, T.J.

    1999-01-01

    We present a new approach to first-principles molecular dynamics that combines a general and flexible interpolation method with ab initio evaluation of the potential energy surface. This hybrid approach extends significantly the domain of applicability of ab initio molecular dynamics. Use of interpolation significantly reduces the computational effort associated with the dynamics over most of the time scale of interest, while regions where potential energy surfaces are difficult to interpolate, for example near conical intersections, are treated by direct solution of the electronic Schroedinger equation during the dynamics. We demonstrate the concept through application to the nonadiabatic dynamics of collisional electronic quenching of Li(2p). Full configuration interaction is used to describe the wave functions of the ground and excited electronic states. The hybrid approach agrees well with full ab initio multiple spawning dynamics, while being more than an order of magnitude faster. copyright 1999 American Institute of Physics

  13. Co-occurrence of dissociative identity disorder and borderline personality disorder.

    Science.gov (United States)

    Ross, Colin A; Ferrell, Lynn; Schroeder, Elizabeth

    2014-01-01

    The literature indicates that, among individuals with borderline personality disorder, pathological dissociation correlates with a wide range of impairments and difficulties in psychological function. It also predicts a poorer response to dialectical behavior therapy for borderline personality disorder. We hypothesized that (a) dissociative identity disorder commonly co-occurs with borderline personality disorder and vice versa, and (b) individuals who meet criteria for both disorders have more comorbidity and trauma than individuals who meet criteria for only 1 disorder. We interviewed a sample of inpatients in a hospital trauma program using 3 measures of dissociation. The most symptomatic group was those participants who met criteria for both borderline personality disorder and dissociative identity disorder on the Dissociative Disorders Interview Schedule, followed by those who met criteria for dissociative identity disorder only, then those with borderline personality disorder only, and finally those with neither disorder. Greater attention should be paid to the relationship between borderline personality disorder and dissociative identity disorder.

  14. Development, Reliability, and Validity of a Child Dissociation Scale.

    Science.gov (United States)

    Putnam, Frank W.; And Others

    1993-01-01

    Evaluation of the Child Dissociative Checklist found it to be a reliable and valid observer report measure of dissociation in children, including sexually abused girls and children with dissociative disorder and with multiple personality disorder. The checklist, which is appended, is intended as a clinical screening instrument and research measure…

  15. Photo-dissociation of hydrogen passivated dopants in gallium arsenide

    International Nuclear Information System (INIS)

    Tong, L.; Larsson, J.A.; Nolan, M.; Murtagh, M.; Greer, J.C.; Barbe, M.; Bailly, F.; Chevallier, J.; Silvestre, F.S.; Loridant-Bernard, D.; Constant, E.; Constant, F.M.

    2002-01-01

    A theoretical and experimental study of the photo-dissociation mechanisms of hydrogen passivated n- and p-type dopants in gallium arsenide is presented. The photo-induced dissociation of the Si Ga -H complex has been observed for relatively low photon energies (3.48 eV), whereas the photo-dissociation of C As -H is not observed for photon energies up to 5.58 eV. This fundamental difference in the photo-dissociation behavior between the two dopants is explained in terms of the localized excitation energies about the Si-H and C-H bonds

  16. Vibrational and cascade dissociation of H{sub 2}{sup +} ions by collision with gas molecules; Dissociation vibrationnelle et dissociation en cascade d'ions H{sub 2}{sup +} par collisions avec les molecules d'un gaz

    Energy Technology Data Exchange (ETDEWEB)

    Verveer, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1966-07-01

    Protons produced by collisional dissociation of H{sub 2}{sup +} ions have an energy spectrum with a narrow central peak. For a part the protons in this peak are produced by vibrational dissociation and for another part by a cascade of two collisions. For H{sub 2}{sup +} ions of 50 to 150 keV the cross section for vibrational dissociation is about 4.1 10{sup -19} cm{sup 2}/molecule in hydrogen and 1.1 10{sup -18} cm{sup 2}/molecule in argon. (author) [French] Les protons resultant de la dissociation par collisions d'ions H{sub 2}{sup +} dans un gaz ont un spectre d'energie qui presente un pic central tres etroit. Les protons dans ce pic proviennent, pour une part de la dissociation vibrationnelle et pour l'autre part d'une suite de deux collisions. Dans le domaine d'energie des ions H{sub 2}{sup +} de 50 a 150 keV la section efficace de dissociation vibrationnel vaut 4.1 10{sup -19} cm{sup 2}/molecule pour l'hydrogene et 1,1 10{sup -18} cm{sup 2}/molecule pour l'argon.

  17. The responses of dissociative patients on the thematic apperception test.

    Science.gov (United States)

    Pica, M; Beere, D; Lovinger, S; Dush, D

    2001-07-01

    This study compared the responses of dissociative inpatients and general inpatient psychiatric controls on the Thematic Apperception Test (TAT; Murray, 1943). We found the stories of dissociative participants to be characterized by a greater interpersonal distance and more trauma and dissociation responses than those of the controls. No significant differences were found regarding total number of emotional references, although references to positive emotions were almost nonexistent for the dissociative group. A post hoc analysis of the data found the testing behaviors of dissociative participants to be characterized by switching, trance states, intrainterview amnesias, and affectively loaded card rejections. Questions were raised regarding the relevancy of the findings to clinical practice and how they might explain some of the controversies surrounding the diagnosis of dissociative identity disorder (DID). Copyright 2001 John Wiley & Sons, Inc.

  18. Ultrafast non-adiabatic dynamics of methyl substituted ethylenes: The π3s Rydberg state

    Science.gov (United States)

    Wu, Guorong; Boguslavskiy, Andrey E.; Schalk, Oliver; Schuurman, Michael S.; Stolow, Albert

    2011-10-01

    Excited state unimolecular reactions of some polyenes exhibit localization of their dynamics at a single ethylenic double bond. Here we present studies of the fundamental photophysical processes in the ethylene unit itself. Combined femtosecond time-resolved photoelectron spectroscopy (TRPES) and ab initio quantum chemical calculations was applied to the study of excited state dynamics in cis-butene, trans-butene, trimethylethylene, and tetramethylethylene, following initial excitation to their respective π3s Rydberg states. The wavelength dependence of the π3s Rydberg state dynamics of tetramethylethylene was investigated in more detail. The π3s Rydberg to ππ* valence state decay rate varies greatly with substituent: the 1,2-di- and tri-methyl substituted ethylenes (cis-butene, trans-butene, and trimethylethylene) show an ultrafast decay (˜20 fs), whereas the fully methylated tetramethylethylene shows a decay rate of 2 to 4 orders of magnitude slower. These observations are rationalized in terms of topographical trends in the relevant potential energy surfaces, as found from ab initio calculations: (1) the barrier between the π3s state and the ππ* state increases with increasing methylation, and (2) the π3s/ππ* minimum energy conical intersection displaces monotonically away from the π3s Franck-Condon region with increasing methylation. The use of systematic methylation in combination with TRPES and ab initio computation is emerging as an important tool in discerning the excited state dynamics of unsaturated hydrocarbons.

  19. Photoleucine Survives Backbone Cleavage by Electron Transfer Dissociation. A Near-UV Photodissociation and Infrared Multiphoton Dissociation Action Spectroscopy Study

    Czech Academy of Sciences Publication Activity Database

    Shaffer, C. J.; Martens, J.; Marek, Aleš; Oomens, J.; Tureček, F.

    2016-01-01

    Roč. 27, č. 7 (2016), s. 1176-1185 ISSN 1044-0305 Institutional support: RVO:61388963 Keywords : peptide ions * electron transfer dissociation * photoleucine label * near-UV photodissociation * infrared multiphoton dissociation action spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.786, year: 2016

  20. Effect of disorder on exciton dissociation in conjugated polymers

    International Nuclear Information System (INIS)

    Feng Yuwen; Zhao Hui; Chen Yuguang; Yan Yonghong

    2017-01-01

    By using a multi-configurational time-dependent Hartree–Fock (MCTDHF) method for the time-dependent Schrödinger equation and a Newtonian equation of motion for lattice, we investigate the disorder effects on the dissociation process of excitons in conjugated polymer chains. The simulations are performed within the framework of an extended version of the Su–Schrieffer–Heeger model modified to include on-site disorder, off-diagonal, electron–electron interaction, and an external electric field. Our results show that Coulomb correlation effects play an important role in determining the exciton dissociation process. The electric field required to dissociate an exciton can practically impossibly occur in a pure polymer chain, especially in the case of triplet exciton. However, when the on-site disorder effects are taken into account, this leads to a reduction in mean dissociation electric fields. As the disorder strength increases, the dissociation field decreases effectively. On the contrary, the effects of off-diagonal disorder are negative in most cases. Moreover, the dependence of exciton dissociation on the conjugated length is also discussed. (paper)

  1. Molecular beam study of dissociative sticking of methane on Ni(100)

    DEFF Research Database (Denmark)

    Holmblad, Peter Mikal; Wambach, Jørg; Chorkendorff, Ib

    1995-01-01

    of the methane leads to a dramatic enhancement of the sticking, emphasizing that the initial vibrational state is of crucial importance. These results are consistent with a mechanism of direct activated dissociative chemisorption where the dynamics is dominated by a barrier in the potential energy surface mainly...... located in the vibrational coordinates. Normal-energy scaling is only approximately observed. The effect of surface temperature is also investigated but is found to be smaller than activation by translational or vibrational energy. A simplified analysis in terms of state resolved sticking curves, Snu...... American Institute of Physics....

  2. Semiclassical calculation for collision induced dissociation. II. Morse oscillator model

    International Nuclear Information System (INIS)

    Rusinek, I.; Roberts, R.E.

    1978-01-01

    A recently developed semiclassical procedure for calculating collision induced dissociation probabilities P/sup diss/ is applied to the collinear collision between a particle and a Morse oscillator diatomic. The particle--diatom interaction is described with a repulsive exponential potential function. P/sup diss/ is reported for a system of three identical particles, as a function of collision energy E/sub t/ and initial vibrational state of the diatomic n 1 . The results are compared with the previously reported values for the collision between a particle and a truncated harmonic oscillator. The two studies show similar features, namely: (a) there is an oscillatory structure in the P/sup diss/ energy profiles, which is directly related to n 1 ; (b) P/sup diss/ becomes noticeable (> or approx. =10 -3 ) for E/sub t/ values appreciably higher than the energetic threshold; (c) vibrational enhancement (inhibition) of collision induced dissociation persists at low (high) energies; and (d) good agreement between the classical and semiclassical results is found above the classical dynamic threshold. Finally, the convergence of P/sup diss/ for increasing box length is shown to be rapid and satisfactory

  3. Data on ionization, excitation, dissociation and dissociative ionization of targets by helium ion bombardments, (1)

    International Nuclear Information System (INIS)

    Oda, Nobuo; Urakawa, Junji

    1984-03-01

    This report presents a compilation of the experimental data on cross sections for the ionization, excitation, dissociation and dissociative ionization processes of targets in helium ion impacts on atoms and molecules under a single collision condition. These measurements were carried out in the energy range from several keV to 3.5 MeV. A systematic survey has been made on the literatures from 1975 to the end of 1982. A list of references is also given, including relevant papers published before 1975. (author)

  4. Hippocampal and Amygdalar Volumes in Dissociative Identity Disorder

    Science.gov (United States)

    Vermetten, Eric; Schmahl, Christian; Lindner, Sanneke; Loewenstein, Richard J.; Bremner, J. Douglas

    2011-01-01

    Objective Smaller hippocampal volume has been reported in several stress-related psychiatric disorders, including posttraumatic stress disorder (PTSD), borderline personality disorder with early abuse, and depression with early abuse. Patients with borderline personality disorder and early abuse have also been found to have smaller amygdalar volume. The authors examined hippocampal and amygdalar volumes in patients with dissociative identity disorder, a disorder that has been associated with a history of severe childhood trauma. Method The authors used magnetic resonance imaging to measure the volumes of the hippocampus and amygdala in 15 female patients with dissociative identity disorder and 23 female subjects without dissociative identity disorder or any other psychiatric disorder. The volumetric measurements for the two groups were compared. Results Hippocampal volume was 19.2% smaller and amygdalar volume was 31.6% smaller in the patients with dissociative identity disorder, compared to the healthy subjects. The ratio of hippocampal volume to amygdalar volume was significantly different between groups. Conclusions The findings are consistent with the presence of smaller hippocampal and amygdalar volumes in patients with dissociative identity disorder, compared with healthy subjects. PMID:16585437

  5. Hippocampal and amygdalar volumes in dissociative identity disorder.

    Science.gov (United States)

    Vermetten, Eric; Schmahl, Christian; Lindner, Sanneke; Loewenstein, Richard J; Bremner, J Douglas

    2006-04-01

    Smaller hippocampal volume has been reported in several stress-related psychiatric disorders, including posttraumatic stress disorder (PTSD), borderline personality disorder with early abuse, and depression with early abuse. Patients with borderline personality disorder and early abuse have also been found to have smaller amygdalar volume. The authors examined hippocampal and amygdalar volumes in patients with dissociative identity disorder, a disorder that has been associated with a history of severe childhood trauma. The authors used magnetic resonance imaging to measure the volumes of the hippocampus and amygdala in 15 female patients with dissociative identity disorder and 23 female subjects without dissociative identity disorder or any other psychiatric disorder. The volumetric measurements for the two groups were compared. Hippocampal volume was 19.2% smaller and amygdalar volume was 31.6% smaller in the patients with dissociative identity disorder, compared to the healthy subjects. The ratio of hippocampal volume to amygdalar volume was significantly different between groups. The findings are consistent with the presence of smaller hippocampal and amygdalar volumes in patients with dissociative identity disorder, compared with healthy subjects.

  6. Geometry effects on magnetization dynamics in circular cross-section wires

    Energy Technology Data Exchange (ETDEWEB)

    Sturma, M. [Univ. Grenoble Alpes, INAC-SPINTEC, F-38000 Grenoble (France); CNRS, SPINTEC, F-38000 Grenoble (France); CEA, INAC-SPINTEC, F-38000 Grenoble (France); Univ. Grenoble Alpes, I. Neel, F-38000 Grenoble (France); CNRS, I. Neel, F-38000 Grenoble (France); Toussaint, J.-C., E-mail: jean-christophe.toussaint@neel.cnrs.fr, E-mail: daria.gusakova@cea.fr [Univ. Grenoble Alpes, I. Neel, F-38000 Grenoble (France); CNRS, I. Neel, F-38000 Grenoble (France); Gusakova, D., E-mail: jean-christophe.toussaint@neel.cnrs.fr, E-mail: daria.gusakova@cea.fr [Univ. Grenoble Alpes, INAC-SPINTEC, F-38000 Grenoble (France); CNRS, SPINTEC, F-38000 Grenoble (France); CEA, INAC-SPINTEC, F-38000 Grenoble (France)

    2015-06-28

    Three-dimensional magnetic memory design based on circular-cross section nanowires with modulated diameter is the emerging field of spintronics. The consequences of the mutual interaction between electron spins and local magnetic moments in such non-trivial geometries are still open to debate. This paper describes the theoretical study of domain wall dynamics within such wires subjected to spin polarized current. We used our home-made finite element software to characterize the variety of domain wall dynamical regimes observed for different constriction to wire diameter ratios d/D. Also, we studied how sizeable geometry irregularities modify the internal micromagnetic configuration and the electron spin spatial distribution in the system, the geometrical reasons underlying the additional contribution to the system's nonadiabaticity, and the specific domain wall width oscillations inherent to fully three-dimensional systems.

  7. Childhood maltreatment and intimate partner violence in dissociative disorder patients.

    Science.gov (United States)

    Webermann, Aliya R; Brand, Bethany L; Chasson, Gregory S

    2014-01-01

    Childhood maltreatment (CM) is a risk factor for subsequent intimate partner violence (IPV) in adulthood, with high rates of retrospectively reported CM among IPV victims and perpetrators. A theorized mechanism of the link between CM and IPV is dissociation. Dissociation may allow perpetrators of violence to remain emotionally distant from their behavior and minimize empathy toward those they victimize, enabling them to commit acts of violence similar to their own experiences. Indeed, elevated rates of dissociation and dissociative disorders (DD) have been found among IPV survivors and perpetrators. In addition, in pilot studies, DD clinicians have reported high levels of violent behavior among DD patients. The present study investigates IPV among DD patients with Dissociative Identity Disorder and Dissociative Disorder Not Otherwise Specified, a group with CM rates of 80-95% and severe dissociative symptoms. DD clinicians reported on rates of CM and IPV among 275 DD patients in outpatient treatment. DD patients also completed a self-report measure of dissociation. Analyses assessed the associations between CM typologies and IPV, as well as trait dissociation and IPV. Physical and emotional child abuse were associated with physical IPV, and childhood witnessing of domestic violence (DV) and childhood neglect were associated with emotional IPV. The present study is the first to provide empirical support for a possible CM to adult IPV developmental trajectory among DD patients. Future research is needed to better understand the link between CM and IPV among those with trauma and DD.

  8. Tunnel ionization of H2 in a low-frequency laser field: A wave-packet approach

    International Nuclear Information System (INIS)

    Nguyen-Dang, T.; Chateauneuf, F.; Manoli, S.; Atabek, O.; Keller, A.

    1997-01-01

    The dynamics of multielectron dissociative ionization (MEDI) of H 2 in an intense IR laser pulse are investigated using a wave-packet propagation scheme. The electron tunneling processes corresponding to the successive ionizations of H 2 are expressed in terms of field-free Born-Oppenheimer (BO) potential energy surfaces (PES) by transforming the tunnel shape resonance picture into a Feshbach resonance problem. This transformation is achieved by defining a new, time-dependent electronic basis in which the bound electrons are still described by field-free BO electronic states while the ionized ones are described by Airy functions. In the adiabatic, quasistatic approximation, these functions describe free electrons under the influence of the instantaneous electric field of the laser and such an ionized electron can have a negative total energy. As a consequence, when dressed by the continuous ejected electron energy, the BO PES of an ionic channel can be brought into resonance with states of the parent species. This construction gives a picture in which wave packets are to be propagated on a continuum of coupled electronic manifolds. A reduction of the wave-packet propagation scheme to an effective five-channel problem has been obtained for the description of the first dissociative ionization process in H 2 by using Fano's formalism [U. Fano, Phys. Rev. 124, 1866 (1961)] to analytically diagonalize the infinite, continuous interaction potential matrix and by using the properties of Fano's solutions. With this algorithm, the effect that continuous ionization of H 2 has on the dissociation dynamics of the H 2 + ion has been investigated. In comparison with results that would be obtained if the first ionization of H 2 was impulsive, the wave-packet dynamics of the H 2 + ion prepared continuously by tunnel ionization are markedly nonadiabatic. (Abstract Truncated)

  9. Dissociation behavior of methane gas hydrate in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, C.; Yu-gang, Y.; Chang-ling, L. [Ministry of Land and Resources, Quindao (China). Qingdao Inst. of Marine Geology; Qing-guo, M. [Qingdao Univ. College of Chemical Engineering and Environment, Shandong, Qingdao (China)

    2008-07-01

    Gas hydrates are ice-like compounds that form by natural gas and water and are considered to be a new energy resource. In order to make good use of this resource, it is important to know the hydrate dissociation process. This paper discussed an investigation of methane hydrate dissociation through a simulation experiment. The paper discussed the gas hydrates dissociation experiment including the apparatus and experiment equipment, including methane gas supply; reaction cell; temperature controller; pressure maintainer; and gas flow meter. The paper also presented the method and material including iso-volumetric dissociation and normal pressure dissociation. Last, results and discussion of the results were presented. A comparison of five different particle sizes did not reveal any obvious effects that were related to the porous media, mostly likely because the particle size was too large. 15 refs., 2 tabs., 4 figs.

  10. The importance of accurate adiabatic interaction potentials for the correct description of electronically nonadiabatic vibrational energy transfer: A combined experimental and theoretical study of NO(v = 3) collisions with a Au(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Golibrzuch, Kai; Shirhatti, Pranav R.; Kandratsenka, Alexander; Wodtke, Alec M.; Bartels, Christof [Institute for Physical Chemistry, Georg August University of Göttingen, Göttingen 37077 (Germany); Max Planck Institute for Biophysical Chemistry, Göttingen 37077 (Germany); Rahinov, Igor [Department of Natural Sciences, The Open University of Israel, Ra' anana 4353701 (Israel); Auerbach, Daniel J. [Institute for Physical Chemistry, Georg August University of Göttingen, Göttingen 37077 (Germany); Max Planck Institute for Biophysical Chemistry, Göttingen 37077 (Germany); Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106 (United States)

    2014-01-28

    We present a combined experimental and theoretical study of NO(v = 3 → 3, 2, 1) scattering from a Au(111) surface at incidence translational energies ranging from 0.1 to 1.2 eV. Experimentally, molecular beam–surface scattering is combined with vibrational overtone pumping and quantum-state selective detection of the recoiling molecules. Theoretically, we employ a recently developed first-principles approach, which employs an Independent Electron Surface Hopping (IESH) algorithm to model the nonadiabatic dynamics on a Newns-Anderson Hamiltonian derived from density functional theory. This approach has been successful when compared to previously reported NO/Au scattering data. The experiments presented here show that vibrational relaxation probabilities increase with incidence energy of translation. The theoretical simulations incorrectly predict high relaxation probabilities at low incidence translational energy. We show that this behavior originates from trajectories exhibiting multiple bounces at the surface, associated with deeper penetration and favored (N-down) molecular orientation, resulting in a higher average number of electronic hops and thus stronger vibrational relaxation. The experimentally observed narrow angular distributions suggest that mainly single-bounce collisions are important. Restricting the simulations by selecting only single-bounce trajectories improves agreement with experiment. The multiple bounce artifacts discovered in this work are also present in simulations employing electronic friction and even for electronically adiabatic simulations, meaning they are not a direct result of the IESH algorithm. This work demonstrates how even subtle errors in the adiabatic interaction potential, especially those that influence the interaction time of the molecule with the surface, can lead to an incorrect description of electronically nonadiabatic vibrational energy transfer in molecule-surface collisions.

  11. Dynamics of electron wave packet in a disordered chain with delayed nonlinear response

    International Nuclear Information System (INIS)

    Zhu Hongjun; Xiong Shijie

    2010-01-01

    We investigate the dynamics of one electron wave packet in a linear chain with random on-site energies and a nonadiabatic electron-phonon interaction which is described by a delayed cubic nonlinear term in the time-dependent Schroedinger equation. We show that in the regime where the wave packet is delocalized in the case with only the delayed nonlinearity, the wave packet becomes localized when the disorder is added and the localization is enhanced by increasing the disorder. In the regime where the self-trapping phenomenon occurs in the case with only the delayed nonlinearity, by adding the disorder the general dynamical features of the wave packet do not change if the nonlinearity parameter is small, but the dynamics shows the subdiffusive behavior if the nonlinearity parameter is large. The numerical results demonstrate complicated wave packet dynamics of systems with both the disorder and nonlinearity.

  12. Dissociative symptomatology in children and adolescents as displayed on psychological testing.

    Science.gov (United States)

    Silberg, J L

    1998-12-01

    The purpose of this study was to investigate psychological testing features of children and adolescents with dissociative disorder diagnoses to provide diagnostic information that might facilitate early intervention. The psychological testing protocols of 30 children diagnosed with dissociative disorders were compared with the testing protocols of 30 consecutive admissions to the Sheppard Pratt Hospital who did not receive a dissociative identity disorder (DID; formerly termed multiple personality disorder) or dissociative disorder not otherwise specified (DDNOS) diagnosis. A rater, blind to the diagnosis, scored these protocols for the presence or absence of behavioral and testing response variables hypothesized to discriminate between the dissociative patients and the mixed group of other diagnoses. Behavioral features significantly more common in the dissociative group included forgetting, staring, unusual motor behaviors, dramatic fluctuations, fearful and angry reactions to stimuli, physical complaints during testing, and expressions of internal conflict. Significant indications of dissociation in the test responses included images of multiplicity, malevolent religiosity, dissociative coping, depersonalized imagery, emotional confusion, extreme dichotomization, images of mutilation and torture, and magical transformation. A combination of these behavioral and response variables was able to select 93% of the dissociative sample. These results add support to the discriminant validity of DID and DDNOS as diagnostic categories in childhood and provide clinical information that may be useful for early diagnosis of traumatized children with dissociative pathology.

  13. Dissociative recombination of molecular ions H2+

    International Nuclear Information System (INIS)

    Abarenov, A.V.; Marchenko, V.S.

    1989-01-01

    The total cross sections of dissociation and dissociative recombination of slow electrons and molecular ions H 2 + have been calculated in terms of the quasiclassical and dipole approximations. In the calculations allowance was made for the quantum nature of vibrational motion of heavy particles and presence of autoionization of divergence states of the H 2 (Σ u , nl) molecules. It is shown that the H 2 + ion dissociation cross sections are dominant in increase of the electron energy in the ε >or approx. 2-3 eV region for H 2 + (v) ion distribution over the vibrational levels characteristic for the beam experiments. 15 refs.; 5 figs

  14. Somatoform and psychoform dissociation among women with orgasmic and sexual pain disorders.

    Science.gov (United States)

    Farina, Benedetto; Mazzotti, Eva; Pasquini, Paolo; Mantione, Maria Giuseppina

    2011-01-01

    Since the 20th century, psychogenic female sexual dysfunctions (FSD), like some somatoform and conversion disorders, have been considered an expression of somatoform dissociation. Several studies have reported dissociative symptoms in different somatoform and conversion disorders, but limited data are available on dissociation among patients with FSD. The aim of this study was to assess somatoform and psychoform dissociation among patients with women's orgasmic disorder, dyspareunia, and vaginismus. A battery of self-administered questionnaires (Somatoform Dissociation Questionnaire, Dissociative Experiences Scale, Hospital Anxiety and Depression Scale, Impact of Event Scale-Revised) was given to 200 gynecological outpatients to assess psychoform and somatoform dissociation and their association with FSD. A strong association between somatoform dissociation and FSD was observed (adjusted odds ratio [OR] = 5.39, 95% confidence interval [CI] = 1.15-25.32), the association between somatoform and psychoform dissociation being estimated by an adjusted OR of 4.83 (95% CI = 1.17-19.91). Our results are compatible with the idea that some forms of FSD could be regarded as somatoform dissociative disorders.

  15. Monitoring conical intersections in the ring opening of furan by attosecond stimulated X-ray Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Weijie Hua

    2016-03-01

    Full Text Available Attosecond X-ray pulses are short enough to capture snapshots of molecules undergoing nonadiabatic electron and nuclear dynamics at conical intersections (CoIns. We show that a stimulated Raman probe induced by a combination of an attosecond and a femtosecond pulse has a unique temporal and spectral resolution for probing the nonadiabatic dynamics and detecting the ultrafast (∼4.5 fs passage through a CoIn. This is demonstrated by a multiconfigurational self-consistent-field study of the dynamics and spectroscopy of the furan ring-opening reaction. Trajectories generated by surface hopping simulations were used to predict Attosecond Stimulated X-ray Raman Spectroscopy signals at reactant and product structures as well as representative snapshots along the conical intersection seam. The signals are highly sensitive to the changes in nonadiabatically coupled electronic structure and geometry.

  16. Systematics of 2-body diffractive dissociations and search of double diffractive dissociation in K-p interactions at 14.3 GeV/c

    International Nuclear Information System (INIS)

    Pons, Yvette.

    1977-12-01

    The diffractive dissociation mechanism is shown to be general when looking at 22 mesonic or baryonic threshold enhancements. The dissociation systems are all produced peripherally and present the property of slope-mass correlation. The production slopes and cross-sections mainly depend on the diffractive excitation mass. The comparison of the results with those from the I.S.R. shows that dissociation systems are very similar in their effective mass shape, momentum transfer structure and angular distributions at center-of-mass energies differing by a factor of ten. Evidence for double diffractive dissociation mechanism is found in 2 exclusive reactions at a cross section level of 5-10+-2 μb. The factorisation hypothesis seems well verified [fr

  17. Coulomb dissociation of N-20,N-21

    NARCIS (Netherlands)

    Roeder, Marko; Adachi, Tatsuya; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M.; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J. G.; Burgunder, G.; Caamano, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkall, Joakim; Chakraborty, S.; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Pramanik, Ushasi Datta; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A.; Farinon, F.; Fraile, Luis M.; Freer, Martin; Freudenberger, M.; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhaeuser, Roman; Goebel, Kathrin; Kalantar-Nayestanaki, Nasser; Najafi, Mohammad Ali; Rigollet, Catherine; Stoica, V.; Streicher, Branislav; Van de Walle, J.

    2016-01-01

    Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N-20,N-21 are reported. Relativistic N-20,N-21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a

  18. Childhood maltreatment and intimate partner violence in dissociative disorder patients

    Directory of Open Access Journals (Sweden)

    Aliya R. Webermann

    2014-09-01

    Full Text Available Background: Childhood maltreatment (CM is a risk factor for subsequent intimate partner violence (IPV in adulthood, with high rates of retrospectively reported CM among IPV victims and perpetrators. A theorized mechanism of the link between CM and IPV is dissociation. Dissociation may allow perpetrators of violence to remain emotionally distant from their behavior and minimize empathy toward those they victimize, enabling them to commit acts of violence similar to their own experiences. Indeed, elevated rates of dissociation and dissociative disorders (DD have been found among IPV survivors and perpetrators. In addition, in pilot studies, DD clinicians have reported high levels of violent behavior among DD patients. Objective: The present study investigates IPV among DD patients with Dissociative Identity Disorder and Dissociative Disorder Not Otherwise Specified, a group with CM rates of 80–95% and severe dissociative symptoms. Methods: DD clinicians reported on rates of CM and IPV among 275 DD patients in outpatient treatment. DD patients also completed a self-report measure of dissociation. Analyses assessed the associations between CM typologies and IPV, as well as trait dissociation and IPV. Results: Physical and emotional child abuse were associated with physical IPV, and childhood witnessing of domestic violence (DV and childhood neglect were associated with emotional IPV. Conclusions: The present study is the first to provide empirical support for a possible CM to adult IPV developmental trajectory among DD patients. Future research is needed to better understand the link between CM and IPV among those with trauma and DD.

  19. Psychiatric comorbidity in patients with conversion disorder and prevalence of dissociative symptoms.

    Science.gov (United States)

    Yayla, Sinan; Bakım, Bahadır; Tankaya, Onur; Ozer, Omer Akil; Karamustafalioglu, Oguz; Ertekin, Hulya; Tekin, Atilla

    2015-01-01

    The 1st objective of the current study was to investigate the frequency and types of dissociative symptoms in patients with conversion disorder (CD). The 2nd objective of the current study was to determine psychiatric comorbidity in patients with and without dissociative symptoms. A total of 54 consecutive consenting patients primarily diagnosed with CD according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, criteria who were admitted to the psychiatric emergency outpatient clinic of Sisli Etfal Research and Teaching Hospital (Istanbul, Turkey) were included in the study. The Structured Clinical Interview for DSM-IV Axis I Disorders, Structured Interview for DSM-IV Dissociative Disorders, and Dissociative Experiences Scale were administered. Study groups consisted of 20 patients with a dissociative disorder and 34 patients without a diagnosis of any dissociative disorder. A total of 37% of patients with CD had any dissociative diagnosis. The prevalence of dissociative disorders was as follows: 18.5% dissociative disorder not otherwise specified, 14.8% dissociative amnesia, and 3.7% depersonalization disorder. Significant differences were found between the study groups with respect to comorbidity of bipolar disorder, past hypomania, and current and past posttraumatic stress disorder (ps = .001, .028, .015, and .028, respectively). Overall comorbidity of bipolar disorder was 27.8%. Psychiatric comorbidity was higher and age at onset was earlier among dissociative patients compared to patients without dissociative symptoms. The increased psychiatric comorbidity and early onset of conversion disorder found in patients with dissociative symptoms suggest that these patients may have had a more severe form of conversion disorder.

  20. Dissociative tendencies and individual differences in high hypnotic suggestibility.

    Science.gov (United States)

    Terhune, Devin Blair; Cardeña, Etzel; Lindgren, Magnus

    2011-03-01

    Inconsistencies in the relationship between dissociation and hypnosis may result from heterogeneity among highly suggestible individuals, in particular the existence of distinct highly suggestible subtypes that are of relevance to models of psychopathology and the consequences of trauma. This study contrasted highly suggestible subtypes high or low in dissociation on measures of hypnotic responding, cognitive functioning, and psychopathology. Twenty-one low suggestible (LS), 19 low dissociative highly suggestible (LDHS), and 11 high dissociative highly suggestible (HDHS) participants were administered hypnotic suggestibility scales and completed measures of free recall, working memory capacity, imagery, fantasy-proneness, psychopathology, and exposure to stressful life events. HDHS participants were more responsive to positive and negative hallucination suggestions and experienced greater involuntariness during hypnotic responding. They also exhibited impaired working memory capacity, elevated pathological fantasy and dissociative symptomatology, and a greater incidence of exposure to stressful life events. In contrast, LDHS participants displayed superior object visual imagery. These results provide further evidence for two highly suggestible subtypes: a dissociative subtype characterised by deficits in executive functioning and a predisposition to psychopathology, and a subtype that exhibits superior imagery and no observable deficits in functioning.

  1. Dissociative part-dependent biopsychosocial reactions to backward masked angry and neutral faces : An fMRI study of dissociative identity disorder

    NARCIS (Netherlands)

    Schlumpf, Yolanda R.; Nijenhuis, Ellert R. S.; Chalavi, Sima; Weder, Ekaterina V.; Zimmermann, Eva; Luechinger, Roger; La Marca, Roberto; Reinders, A. A. T. Simone; Jaencke, Lutz

    2013-01-01

    Objective: The Theory of Structural Dissociation of the Personality (TSDP) proposes that dissociative identity disorder (DID) patients are fixed in traumatic memories as "Emotional Parts" (EP), but mentally avoid these as "Apparently Normal Parts" of the personality (ANP). We tested the hypotheses

  2. Unresolved mourning, supernatural beliefs and dissociation: a mediation analysis.

    Science.gov (United States)

    Thomson, Paula; Jaque, S Victoria

    2014-01-01

    Unresolved mourning is marked by disorganized behavior and states of mind. In this study, we speculated that pathological dissociation would mediate the effects of unresolved mourning on supernatural beliefs. This hypothesis was determined based on findings that indicate an association between higher levels of dissociation, stronger beliefs in the supernatural and unresolved mourning. We examined two groups of participants, one classified as non-unresolved (non-U) (n = 56) and the other as unresolved (n = 26) (U) with respect to past loss/trauma as measured by the Adult Attachment Interview (AAI). Two self-report instruments were administered to measure supernatural beliefs and dissociation. As hypothesized, the multivariate analysis of variance indicated mean differences between the two groups. The unresolved group had greater belief in the supernatural and more pathological dissociative processes. The mediation analysis demonstrated that pathological dissociation fully mediated the effects of unresolved mourning on supernatural beliefs.

  3. Non-adiabatic quantum evolution: The S matrix as a geometrical phase factor

    Energy Technology Data Exchange (ETDEWEB)

    Saadi, Y., E-mail: S_yahiadz@yahoo.fr [Laboratoire de Physique Quantique et Systèmes Dynamiques, Faculté des Sciences, Université Ferhat Abbas de Sétif, Sétif 19000 (Algeria); Maamache, M. [Laboratoire de Physique Quantique et Systèmes Dynamiques, Faculté des Sciences, Université Ferhat Abbas de Sétif, Sétif 19000 (Algeria)

    2012-03-19

    We present a complete derivation of the exact evolution of quantum mechanics for the case when the underlying spectrum is continuous. We base our discussion on the use of the Weyl eigendifferentials. We show that a quantum system being in an eigenstate of an invariant will remain in the subspace generated by the eigenstates of the invariant, thereby acquiring a generalized non-adiabatic or Aharonov–Anandan geometric phase linked to the diagonal element of the S matrix. The modified Pöschl–Teller potential and the time-dependent linear potential are worked out as illustrations. -- Highlights: ► In this Letter we study the exact quantum evolution for continuous spectra problems. ► We base our discussion on the use of the Weyl eigendifferentials. ► We give a generalized Lewis and Riesenfeld phase for continuous spectra. ► This generalized phase or Aharonov–Anandan geometric phase is linked to the S matrix. ► The modified Pöschl–Teller and the linear potential are worked out as illustrations.

  4. Automated and high confidence protein phosphorylation site localization using complementary collision-activated dissociation and electron transfer dissociation tandem mass spectrometry

    DEFF Research Database (Denmark)

    Hansen, Thomas A; Sylvester, Marc; Jensen, Ole N

    2012-01-01

    -site localization and the number of assigned phospho-sites at a fixed false-localization rate. The average calculated Cscore from a large data set (>7000 phosphopeptide MS/MS spectra) was ∼32 compared to ∼23 and ∼17 for the Ascore using collision-activated dissociation (CAD) or electron transfer dissociation (ETD...... peptide fragmentation and the loss of labile phosphate groups complicate identification of the site of the phosphate motif. Here, we have implemented and evaluated a novel approach for phospho-site localization by the combined use of peptide tandem mass spectrometry data obtained using both collision......-activated dissociation and electron transfer dissociation, an approach termed the Cscore. The scoring algorithm used in the Cscore was adapted from the widely used Ascore method. The analytical benefit of integrating the product ion information of both ETD and CAD data are evident by increased confidence in phospho...

  5. Quantum State-Resolved Collision Dynamics of Nitric Oxide at Ionic Liquid and Molten Metal Surfaces

    Science.gov (United States)

    Zutz, Amelia Marie

    Detailed molecular scale interactions at the gas-liquid interface are explored with quantum state-to-state resolved scattering of a jet-cooled beam of NO(2pi1/2; N = 0) from ionic liquid and molten metal surfaces. The scattered distributions are probed via laser-induced fluorescence methods, which yield rotational and spin-orbit state populations that elucidate the dynamics of energy transfer at the gas-liquid interface. These collision dynamics are explored as a function of incident collision energy, surface temperature, scattering angle, and liquid identity, all of which are found to substantially affect the degree of rotational, electronic and vibrational excitation of NO via collisions at the liquid surface. Rotational distributions observed reveal two distinct scattering pathways, (i) molecules that trap, thermalize and eventually desorb from the surface (trapping-desorption, TD), and (ii) those that undergo prompt recoil (impulsive scattering, IS) prior to complete equilibration with the liquid surface. Thermally desorbing NO molecules are found to have rotational temperatures close to, but slightly cooler than the surface temperature, indicative of rotational dependent sticking probabilities on liquid surfaces. Nitric oxide is a radical with multiple low-lying electronic states that serves as an ideal candidate for exploring nonadiabatic state-changing collision dynamics at the gas-liquid interface, which induce significant excitation from ground (2pi1/2) to excited (2pi 3/2) spin-orbit states. Molecular beam scattering of supersonically cooled NO from hot molten metals (Ga and Au, Ts = 300 - 1400 K) is also explored, which provide preliminary evidence for vibrational excitation of NO mediated by thermally populated electron-hole pairs in the hot, conducting liquid metals. The results highlight the presence of electronically nonadiabatic effects and build toward a more complete characterization of energy transfer dynamics at gas-liquid interfaces.

  6. Schizophrenia masquerading as Dissociative Identity Disorder

    OpenAIRE

    Jegan Yogaratnam; Rajesh Jacob

    2012-01-01

    Dissociative symptoms can dominate the clinical picture in many psychiatric conditions and possess a huge challenge to the clinicians in management. We present a case report of a female with a strong family history of schizophrenia who initially presented with features suggestive of dissociative identity disorder, which is itself a rare clinical entity, was later diagnosed to have schizophrenia. Authors would like to emphasise that clinicians should have a high index of suspicion for schizoph...

  7. Time-resolved photoelectron spectroscopy and ab initio multiple spawning studies of hexamethylcyclopentadiene

    DEFF Research Database (Denmark)

    Wolf, T. J. A.; Kuhlman, Thomas Scheby; Schalk, O.

    2014-01-01

    Time-resolved photoelectron spectroscopy and ab initio multiple spawning were applied to the ultrafast non-adiabatic dynamics of hexamethylcyclopentadiene. The high level of agreement between experiment and theory associates wavepacket motion with a distinct degree of freedom.......Time-resolved photoelectron spectroscopy and ab initio multiple spawning were applied to the ultrafast non-adiabatic dynamics of hexamethylcyclopentadiene. The high level of agreement between experiment and theory associates wavepacket motion with a distinct degree of freedom....

  8. Dissociative Identity Disorder

    Science.gov (United States)

    Schmidt, Tom

    2007-01-01

    Few psychological disorders in the Diagnostic Statistical Manual have generated as much controversy as Dissociative Identity Disorder (DID). For the past 35 years diagnoses of DID, previously referred to as Multiple Personality Disorder (MPD), have increased exponentially, causing various psychological researchers and clinicians to question the…

  9. Dissociative Photoionization of Diethyl Ether.

    Science.gov (United States)

    Voronova, Krisztina; Mozaffari Easter, Chrissa M; Covert, Kyle J; Bodi, Andras; Hemberger, Patrick; Sztáray, Bálint

    2015-10-29

    The dissociative photoionization of internal energy selected diethyl ether ions was investigated by imaging photoelectron photoion coincidence spectroscopy. In a large, 5 eV energy range Et2O(+) cations decay by two parallel and three sequential dissociative photoionization channels, which can be modeled well using statistical theory. The 0 K appearance energies of the CH3CHOCH2CH3(+) (H-loss, m/z = 73) and CH3CH2O═CH2(+) (methyl-loss, m/z = 59) fragment ions were determined to be 10.419 ± 0.015 and 10.484 ± 0.008 eV, respectively. The reemergence of the hydrogen-loss ion above 11 eV is attributed to transition-state (TS) switching, in which the second, outer TS is rate-determining at high internal energies. At 11.81 ± 0.05 eV, a secondary fragment of the CH3CHOCH2CH3(+) (m/z = 73) ion, protonated acetaldehyde, CH3CH═OH(+) (m/z = 45) appears. On the basis of the known thermochemical onset of this fragment, a reverse barrier of 325 meV was found. Two more sequential dissociation reactions were examined, namely, ethylene and formaldehyde losses from the methyl-loss daughter ion. The 0 K appearance energies of 11.85 ± 0.07 and 12.20 ± 0.08 eV, respectively, indicate no reverse barrier in these processes. The statistical model of the dissociative photoionization can also be used to predict the fractional ion abundances in threshold photoionization at large temperatures, which could be of use in, for example, combustion diagnostics.

  10. Cognitive Processes in Dissociation: Comment on Giesbrecht et al. (2008)

    Science.gov (United States)

    Bremner, J. Douglas

    2010-01-01

    In their recent review "Cognitive Processes in Dissociation: An Analysis of Core Theoretical Assumptions," published in "Psychological Bulletin", Giesbrecht, Lynn, Lilienfeld, and Merckelbach (2008) have challenged the widely accepted trauma theory of dissociation, which holds that dissociative symptoms are caused by traumatic stress. In doing so,…

  11. Dissociative stupor mimicking consciousness disorder in an advanced lung cancer patient.

    Science.gov (United States)

    Tada, Yukio; Okano, Tetsuya; Kaga, Akiko; Yamazaki, Susumu; Kawada, Satoshi; Ishida, Mayumi; Kobayashi, Kunihiko; Onishi, Hideki

    2012-06-01

    Although there are three kinds of stupor in psychiatry, dissociative stupor is the most commonly recognized. In psychiatric clinics or emergency rooms, dissociative stupor is common, but in an oncology setting it is hardly known. Therefore, distinguishing dissociative stupor from consciousness disorder is occasionally difficult, especially in the advanced or terminal phase. We report an advanced lung cancer patient who presented dissociative stupor mimicking consciousness disorder. It is necessary to distinguish between consciousness disorder and dissociative stupor. In addition, consultation with a psychiatrist should be taken into consideration.

  12. [Dissociative identity disorder or schizophrenia?].

    Science.gov (United States)

    Tschöke, S; Steinert, T

    2010-01-01

    We present a case of dissociative identity disorder in which Schneiderian first rank symptoms were present besides of various states of consciousness. Thus the diagnosis of schizophrenia had to be considered. Formally, the symptoms met ICD-10 criteria for schizophrenia. However, taking into account the lack of formal thought disorder and of negative symptoms as well as a typical history of severe and prolonged traumatisation, we did not diagnose a co-morbid schizophrenic disorder. There is good evidence for the existence of psychotic symptoms among patients with dissociative disorders. However, in clinical practice this differential diagnosis is rarely considered.

  13. Resonant and off-resonant transients in electromagnetically induced transparency: Turn-on and turn-off dynamics

    International Nuclear Information System (INIS)

    Greentree, Andrew D.; Smith, T.B.; Echaniz, S.R. de; Durrant, A. V.; Marangos, J.P.; Segal, D.M.; Vaccaro, J.A.

    2002-01-01

    This paper presents a wide-ranging theoretical and experimental study of nonadiabatic transient phenomena in a Λ electromagnetically induced transparency system when a strong coupling field is rapidly switched on or off. The theoretical treatment uses a Laplace transform approach to solve the time-dependent density matrix equation. The experiments are carried out in a 87 Rb magneto-optical trap. The results show transient probe gain in parameter regions not previously studied, and provide insight into the transition dynamics between bare and dressed states

  14. Structure sensitivity of CO dissociation on Rh surfaces

    DEFF Research Database (Denmark)

    Mavrikakis, Manos; Baumer, M.; Freund, H.J.

    2002-01-01

    than the flat surface, but the effect is considerably weaker than the effect of surface structure on the dissociation barrier. Our findings are compared with available experimental data, and the consequences for CO activation in methanation and Fischer-Tropsch reactions are discussed.......Using periodic self-consistent density functional calculations it is shown that the barrier for CO dissociation is similar to120 kJ/mol lower on the stepped Rh(211) surface than on the close-packed Rh(111) surface. The stepped surface binds molecular CO and the dissociation products more strongly...

  15. Fluids, superfluids and supersolids: dynamics and cosmology of self-gravitating media

    Energy Technology Data Exchange (ETDEWEB)

    Celoria, Marco [Gran Sasso Science Institute (INFN), Via Francesco Crispi 7, I-67100 L' Aquila (Italy); Comelli, Denis [INFN, Sezione di Ferrara, I-35131 Ferrara (Italy); Pilo, Luigi, E-mail: marco.celoria@gssi.infn.it, E-mail: comelli@fe.infn.it, E-mail: luigi.pilo@aquila.infn.it [Dipartimento di Fisica, Università di L' Aquila, I-67010 L' Aquila (Italy)

    2017-09-01

    We compute cosmological perturbations for a generic self-gravitating media described by four derivatively-coupled scalar fields. Depending on the internal symmetries of the action for the scalar fields, one can describe perfect fluids, superfluids, solids and supersolids media. Symmetries dictate both dynamical and thermodynamical properties of the media. Generically, scalar perturbations include, besides the gravitational potential, an additional non-adiabatic mode associated with the entropy per particle σ. While perfect fluids and solids are adiabatic with σ constant in time, superfluids and supersolids feature a non-trivial dynamics for σ. Special classes of isentropic media with zero σ can also be found. Tensor modes become massive for solids and supersolids. Such an effective approach can be used to give a very general and symmetry driven modelling of the dark sector.

  16. Strategic use of dissociation in ethical argumentation on abortion

    Directory of Open Access Journals (Sweden)

    Simona Mazilu

    2008-01-01

    Full Text Available This paper is concerned with the dialectical and rhetorical consequences of the use of dissociation in ethical argumentation on abortion. Disputants make strategic use of dissociation to advance their standpoints, to establish the starting points of the discussion and to argue in favor or against abortion as well. From the pragma-dialectical perspective (van Rees 2002, 2003, 2005a, 2005b, 2006, dissociation is defined as an argumentative technique by which a unitary concept is divided into two different concepts of which one is intended as positive while the other one as negative. The analysis of a religious text on abortion shows that by means of dissociation abortion can be conceived of as “an unspeakable crime” or “the deliberate killing of an innocent human being” as opposed to “interruption of pregnancy”, the term preferred by pro-choice supporters. I claim that the protagonist uses dissociation as a rhetorical strategy aimed at persuading both the interlocutor and the audience.

  17. Nonadiabatic two-electron transfer mediated by an irregular bridge

    International Nuclear Information System (INIS)

    Petrov, E.G.; Shevchenko, Ye.V.; May, V.

    2004-01-01

    Nonadiabatic two-electron transfer (TET) mediated by a linear molecular bridge is studied theoretically. Special attention is put on the case of a irregular distribution of bridge site energies as well as on the inter-site Coulomb interaction. Based on the unified description of electron transfer reactions [J. Chem. Phys. 115 (2001) 7107] a closed set of kinetic equations describing the TET process is derived. A reduction of this set to a single exponential donor-acceptor (D-A) TET is performed together with a derivation of an overall D-A TET rate. The latter contains a contribution of the stepwise as well as of the concerted route of D-A TET. The stepwise contribution is determined by two single-electron steps each of them associated with a sequential and a superexchange pathway. A two-electron unistep superexchange transition between the D and A forms the concerted contribution to the overall rate. Both contributions are analyzed in their dependency on the bridge length. The irregular distribution of the bridge site energies as well as the influence of the Coulomb interaction facilitates the D-A TET via a modification of the stepwise and the concerted part of the overall rate. At low temperatures and for short bridges with a single or two units the concerted contribution exceeds the stepwise contribution. If the bridge contains more than two units, the stepwise contribution dominates the overall rate

  18. Seniority number description of potential energy surfaces: Symmetric dissociation of water, N2, C2, and Be2

    International Nuclear Information System (INIS)

    Bytautas, Laimutis; Scuseria, Gustavo E.; Ruedenberg, Klaus

    2015-01-01

    The present study further explores the concept of the seniority number (Ω) by examining different configuration interaction (CI) truncation strategies in generating compact wave functions in a systematic way. While the role of Ω in addressing static (strong) correlation problem has been addressed in numerous previous studies, the usefulness of seniority number in describing weak (dynamic) correlation has not been investigated in a systematic way. Thus, the overall objective in the present work is to investigate the role of Ω in addressing also dynamic electron correlation in addition to the static correlation. Two systematic CI truncation strategies are compared beyond minimal basis sets and full valence active spaces. One approach is based on the seniority number (defined as the total number of singly occupied orbitals in a determinant) and another is based on an excitation-level limitation. In addition, molecular orbitals are energy-optimized using multiconfigurational-self-consistent-field procedure for all these wave functions. The test cases include the symmetric dissociation of water (6-31G), N 2 (6-31G), C 2 (6-31G), and Be 2 (cc-pVTZ). We find that the potential energy profile for H 2 O dissociation can be reasonably well described using only the Ω = 0 sector of the CI wave function. For the Be 2 case, we show that the full CI potential energy curve (cc-pVTZ) is almost exactly reproduced using either Ω-based (including configurations having up to Ω = 2 in the virtual-orbital-space) or excitation-based (up to single-plus-double-substitutions) selection methods, both out of a full-valence-reference function. Finally, in dissociation cases of N 2 and C 2 , we shall also consider novel hybrid wave functions obtained by a union of a set of CI configurations representing the full valence space and a set of CI configurations where seniority-number restriction is imposed for a complete set (full-valence-space and virtual) of correlated molecular orbitals

  19. PTSD, emotion dysregulation, and dissociative symptoms in a highly traumatized sample

    Science.gov (United States)

    Powers, Abigail; Cross, Dorthie; Fani, Negar; Bradley, Bekh

    2015-01-01

    Exposure to multiple traumas has been shown to result in many negative mental health outcomes, including posttraumatic stress disorder (PTSD). Dissociation, which involves disruptions in memory, identity, and perceptions, may be a component of PTSD, particularly among individuals who have experienced childhood trauma. Emotion regulation difficulties are also strongly associated with childhood trauma and emotion dysregulation may be a particularly important factor to consider in the development and maintenance of dissociative symptoms. The goal of the present study was to determine whether emotion dysregulation mediated the relationship between PTSD symptoms and dissociation in a sample of 154 (80% female, 97% African-American) adults recruited from a public, urban hospital. PTSD was measured using the Clinician Administered PTSD Scale, emotion dysregulation was measured using the Difficulties in Emotion Regulation Scale, and dissociation was measured using the Multiscale Dissociation Inventory. A linear regression analysis showed that both PTSD and emotion dysregulation were statistically significant predictors of dissociation even after controlling for trauma exposure. Alexithymia and an inability to use emotion regulation strategies in particular were predictive of dissociation above and beyond other predictor variables. Using bootstrapping techniques, we found that overall emotion dyregulation partially mediated the effect of PTSD symptoms on dissociative symptoms. Our results suggest that emotion dysregulation may be important in understanding the relation between PTSD and dissociative symptoms. Treatment approaches may consider a focus on training in emotional understanding and the development of adaptive regulation strategies as a way to address dissociative symptoms in PTSD patients. PMID:25573648

  20. Strong field control of predissociation dynamics.

    Science.gov (United States)

    Corrales, María E; Balerdi, Garikoitz; Loriot, Vincent; de Nalda, Rebeca; Bañares, Luis

    2013-01-01

    Strong field control scenarios are investigated in the CH3I predissociation dynamics at the origin of the second absorption B-band, in which state-selective electronic predissociation occurs through the crossing with a valence dissociative state. Dynamic Stark control (DSC) and pump-dump strategies are shown capable of altering both the predissociation lifetime and the product branching ratio.