Non-Relativistic Superstring Theories
Energy Technology Data Exchange (ETDEWEB)
Kim, Bom Soo
2007-12-14
We construct a supersymmetric version of the 'critical' non-relativistic bosonic string theory [1] with its manifest global symmetry. We introduce the anticommuting bc CFT which is the super partner of the {beta}{gamma} CFT. The conformal weights of the b and c fields are both 1/2. The action of the fermionic sector can be transformed into that of the relativistic superstring theory. We explicitly quantize the theory with manifest SO(8) symmetry and find that the spectrum is similar to that of Type IIB superstring theory. There is one notable difference: the fermions are non-chiral. We further consider 'noncritical' generalizations of the supersymmetric theory using the superspace formulation. There is an infinite range of possible string theories similar to the supercritical string theories. We comment on the connection between the critical non-relativistic string theory and the lightlike Linear Dilaton theory.
Quantum mechanics non-relativistic theory
Landau, Lev Davidovich
1977-01-01
This edition has been completely revised to include some 20% of new material. Important recent developments such as the theory of Regge poles are now included. Many problems with solutions have been added to those already contained in the book.
Holographic stress tensor for non-relativistic theories
International Nuclear Information System (INIS)
Ross, Simon F.; Saremi, Omid
2009-01-01
We discuss the calculation of the field theory stress tensor from the dual geometry for two recent proposals for gravity duals of non-relativistic conformal field theories. The first of these has a Schroedinger symmetry including Galilean boosts, while the second has just an anisotropic scale invariance (the Lifshitz case). For the Lifshitz case, we construct an appropriate action principle. We propose a definition of the non-relativistic stress tensor complex for the field theory as an appropriate variation of the action in both cases. In the Schroedinger case, we show that this gives physically reasonable results for a simple black hole solution and agrees with an earlier proposal to determine the stress tensor from the familiar AdS prescription. In the Lifshitz case, we solve the linearised equations of motion for a general perturbation around the background, showing that our stress tensor is finite on-shell.
OTR from Non-Relativistic Electrons
Bal, C; Chevallay, E; Lefèvre, T; Suberlucq, Guy
2003-01-01
The CLIC Test Facility 3 (CTF3) injector will provide pulsed beams of high average current; 5A over 1.56µs at 140keV. For transverse beam sizes of the order of 1mm, as foreseen, this implies serious damage to the commonly used scintillating screens. Optical Transition Radiation from thermally resistant radiators represents a possible alternative. In this context, the backward OTR radiation emitted from an aluminium screen by a 80keV, 60nC, 4ns electron pulse has been investigated. The experimental results are in good agreement with the theoretical expectations, indicating a feeble light intensity distributed over a large solid angle. Our conclusions for the design of the CTF3 injector profile monitor are also given.
Dielectric laser acceleration of non-relativistic electrons at a photonic structure
Energy Technology Data Exchange (ETDEWEB)
Breuer, John
2013-08-29
This thesis reports on the observation of dielectric laser acceleration of non-relativistic electrons via the inverse Smith-Purcell effect in the optical regime. Evanescent modes in the vicinity of a periodic grating structure can travel at the same velocity as the electrons along the grating surface. A longitudinal electric field component is used to continuously impart momentum onto the electrons. This is only possible in the near-field of a suitable photonic structure, which means that the electron beam has to pass the structure within about one wavelength. In our experiment we exploit the third spatial harmonic of a single fused silica grating excited by laser pulses derived from a Titanium:sapphire oscillator and accelerate non-relativistic 28 keV electrons. We measure a maximum energy gain of 280 eV, corresponding to an acceleration gradient of 25 MeV/m, already comparable with state-of-the-art radio-frequency linear accelerators. To experience this acceleration gradient the electrons approach the grating closer than 100 nm. We present the theory behind grating-based particle acceleration and discuss simulation results of dielectric laser acceleration in the near-field of photonic grating structures, which is excited by near-infrared laser light. Our measurements show excellent agreement with our simulation results and therefore confirm the direct acceleration with the light field. We further discuss the acceleration inside double grating structures, dephasing effects of non-relativistic electrons as well as the space charge effect, which can limit the attainable peak currents of these novel accelerator structures. The photonic structures described in this work can be readily concatenated and therefore represent a scalable realization of dielectric laser acceleration. Furthermore, our structures are directly compatible with the microstructures used for the acceleration of relativistic electrons demonstrated in parallel to this work by our collaborators in
Dielectric laser acceleration of non-relativistic electrons at a photonic structure
International Nuclear Information System (INIS)
Breuer, John
2013-01-01
This thesis reports on the observation of dielectric laser acceleration of non-relativistic electrons via the inverse Smith-Purcell effect in the optical regime. Evanescent modes in the vicinity of a periodic grating structure can travel at the same velocity as the electrons along the grating surface. A longitudinal electric field component is used to continuously impart momentum onto the electrons. This is only possible in the near-field of a suitable photonic structure, which means that the electron beam has to pass the structure within about one wavelength. In our experiment we exploit the third spatial harmonic of a single fused silica grating excited by laser pulses derived from a Titanium:sapphire oscillator and accelerate non-relativistic 28 keV electrons. We measure a maximum energy gain of 280 eV, corresponding to an acceleration gradient of 25 MeV/m, already comparable with state-of-the-art radio-frequency linear accelerators. To experience this acceleration gradient the electrons approach the grating closer than 100 nm. We present the theory behind grating-based particle acceleration and discuss simulation results of dielectric laser acceleration in the near-field of photonic grating structures, which is excited by near-infrared laser light. Our measurements show excellent agreement with our simulation results and therefore confirm the direct acceleration with the light field. We further discuss the acceleration inside double grating structures, dephasing effects of non-relativistic electrons as well as the space charge effect, which can limit the attainable peak currents of these novel accelerator structures. The photonic structures described in this work can be readily concatenated and therefore represent a scalable realization of dielectric laser acceleration. Furthermore, our structures are directly compatible with the microstructures used for the acceleration of relativistic electrons demonstrated in parallel to this work by our collaborators in
Some no-go theorems for string duals of non-relativistic Lifshitz-like theories
International Nuclear Information System (INIS)
Li Wei; Takayanagi, Tadashi; Nishioka, Tatsuma
2009-01-01
We study possibilities of string theory embeddings of the gravity duals for non-relativistic Lifshitz-like theories with anisotropic scale invariance. We search classical solutions in type IIA and eleven-dimensional supergravities which are expected to be dual to (2+1)-dimensional Lifshitz-like theories. Under reasonable ansaetze, we prove that such gravity duals in the supergravities are not possible. We also discuss a possible physical reason behind this.
More effective field theory for non-relativistic scattering
International Nuclear Information System (INIS)
Kaplan, D.B.
1997-01-01
An effective field theory treatment of nucleon-nucleon scattering at low energy shows much promise and could prove to be a useful tool in the study of nuclear matter at both ordinary and extreme densities. The analysis is complicated by the existence a large length scale - the scattering length -which arises due to couplings in the short distance theory being near critical values. I show how this can be dealt with by introducing an explicit s-channel state in the effective field theory. The procedure is worked out analytically in a toy example. I then demonstrate that a simple effective field theory excellently reproduces the 1 S 0 np phase shift up to the pion production threshold. (orig.)
Dynamic of non relativistic electrons and protons in the plasmasphere
International Nuclear Information System (INIS)
Mendes Junior, O.; Pinto Junior, O.; Gonzalez, W.D.
1985-01-01
A study of the dynamics of electrons and protons inside the plasmasphere is presented. These particles are subjected to the geomagnetic field and to plasmaspheric electric fields, given by simple static models, during magnetically quiet and disturbed periods. (author) [pt
The infrared problem for the dressed non-relativistic electron in a magnetic field
International Nuclear Information System (INIS)
Amour, L.; Faupin, J.; Grebert, B.; Guillot, J.C.
2008-01-01
We consider a non-relativistic electron interacting with a classical magnetic field pointing along the x 3 -axis and with a quantized electromagnetic field. The system is translation invariant in the x 3 -direction and the corresponding Hamiltonian has a decomposition H ≅∫ R + H(P 3 )dP 3 . For a fixed momentum P 3 sufficiently small, we prove that H(P 3 ) has a ground state in the Fock representation if and only if E'(P 3 )=0, where P 3 →E'(P 3 ) is the derivative of the map P 3 →E(P 3 )=infσ(H(P 3 )). If E'(P 3 )≠0, we obtain the existence of a ground state in a non-Fock representation. This result holds for sufficiently small values of the coupling constant. (authors)
Quantum mechanics. A basic course of non-relativistic quantum theory. 2. rev. and upd. ed.
International Nuclear Information System (INIS)
Straumann, Norbert
2013-01-01
The following topics are dealt with: Matter waves and Schroedinger equation, the statistical interpretation of the wave function, uncertainty relations and measuring process, the formal principles of quantum mechanics, angular momentum and particles with spin, perturbation theory and applications, many-electron systems, scattering theory, quantum chemistry, time dependent perturbation theory, fundamental problems of quantum mechanics. (HSI)
Energy Technology Data Exchange (ETDEWEB)
Amour, L. [Reims Univ., Lab. de Mathematiques EDPPM, FRE-CNRS 3111, 51 (France); Faupin, J. [Aarhus Univ., Institut for Matematiske Fag (Denmark); Grebert, B. [Nantes Univ, Lab. de Mathematiques Jean-Leray, UMR-CNRS 6629 (France); Guillot, J.C. [Ecole Polytechnique, Centre de Mathematiques Appliquees, UMR-CNRS 7641, 91 - Palaiseau (France)
2008-10-15
We consider a non-relativistic electron interacting with a classical magnetic field pointing along the x{sub 3}-axis and with a quantized electromagnetic field. The system is translation invariant in the x{sub 3}-direction and the corresponding Hamiltonian has a decomposition H {approx_equal}{integral}{sub R}{sup +}H(P{sub 3})dP{sub 3}. For a fixed momentum P{sub 3} sufficiently small, we prove that H(P{sub 3}) has a ground state in the Fock representation if and only if E'(P{sub 3})=0, where P{sub 3} {yields}E'(P{sub 3}) is the derivative of the map P{sub 3}{yields}E(P{sub 3})=inf{sigma}(H(P{sub 3})). If E'(P{sub 3}){ne}0, we obtain the existence of a ground state in a non-Fock representation. This result holds for sufficiently small values of the coupling constant. (authors)
Zocco, Alessandro
2017-12-01
The properties of a non-relativistic magnetised low-beta electron-positron plasma in slab geometry are investigated. The two species are taken to be drift kinetic while we retain Larmor radius effects in quasi-neutrality, and inertia in Ohm's law. A linear analysis shows that, for small magnetic perturbations, Alfvénic perturbations travel at the electron Alfvén speed, which is based on the electron mass. We discuss the role of the displacement current when Larmor-scale and Debye-scale effects are both retained. We predict the existence of a kinetic electron Alfvén wave which connects to the K-modes of Mishchenko et al. (J. Plasma Phys., 2017 (submitted)) in the electrostatic limit. It is found that linear drift waves are not supported by the system if the two species have the same temperature. Tearing modes can be driven unstable by equilibrium current density gradients. Also in this case, the characteristic time is based on the electron Alfvén speed. Nonlinear hybrid fluid-kinetic equations are also derived. It is shown that each species is described, to leading order, by the kinetic reduced electron heating model (KREHM) kinetic equation of Zocco & Schekochihin (Phys. Plasmas, vol. 18, 2011, 102309). The model is extended to retain first-order Larmor radius effects. It supports collisionless dispersive waves, which can greatly impact nonlinear magnetic reconnection. Diamagnetic effects enter the nonlinear equations via the first-order magnetic compressibility. A minimal nonlinear model for two-dimensional low-frequency isothermal pair plasmas is derived.
Non-relativistic supersymmetry
International Nuclear Information System (INIS)
Clark, T.E.; Love, S.T.
1984-01-01
The most general one- and two-body hamiltonian invariant under galilean supersymmetry is constructed in superspace. The corresponding Feynman rules are given for the superfield Green functions. As demonstrated by a simple example, it is straightforward to construct models in which the supersymmetry is spontaneously broken by the non-relativistic vacuum. (orig.)
Hoefener, S.; Ahlrichs, R.; Knecht, S.; Visscher, L.
2012-01-01
We report results of non-relativistic and two-component relativistic single-reference coupled-cluster with single and double and perturbative triple excitations [CCSD(T)] treatments for the 4p-block dimers Ga
Mosquera, Martín A.
2017-10-01
Provided the initial state, the Runge-Gross theorem establishes that the time-dependent (TD) external potential of a system of non-relativistic electrons determines uniquely their TD electronic density, and vice versa (up to a constant in the potential). This theorem requires the TD external potential and density to be Taylor-expandable around the initial time of the propagation. This paper presents an extension without this restriction. Given the initial state of the system and evolution of the density due to some TD scalar potential, we show that a perturbative (not necessarily weak) TD potential that induces a non-zero divergence of the external force-density, inside a small spatial subset and immediately after the initial propagation time, will cause a change in the density within that subset, implying that the TD potential uniquely determines the TD density. In this proof, we assume unitary evolution of wavefunctions and first-order differentiability (which does not imply analyticity) in time of the internal and external force-densities, electronic density, current density, and their spatial derivatives over the small spatial subset and short time interval.
Holographic View of Non-relativistic Physics
Balasubramanian, Koushik
Motivated by the AdS/CFT correspondence for relativistic CFTs, it seems natural to generalize it to non-relativistic CFTs. Such a dual description could provide insight into strong coupling phenomena observed in condensed matter systems. Scale invariance can be realized in non-relativistic theories in many ways. One freedom is the relative scale dimension of time and space, called the dynamical exponent z. In this thesis, we will mainly focus on the case where z = 2, however gravity duals for other values of z have also been found. In the first part of the thesis, we study NRCFTs that are Galilean invariant. Discrete light cone quantization (DLCQ) of N = 4 super Yang-Mills theory is an example of such a system with z = 2 scaling symmetry. A more realistic example of a system with the same set of symmetries is a system of cold fermions at unitarity. These non-relativistic systems respect a symmetry algebra known as the Schrodinger algebra. We propose a gravity dual that realizes the symmetries of the Schrodinger algebra as isometries. An unusual feature of this duality is that the bulk geometry has two extra dimensions than the CFT, instead of the usual one. The additional direction is a compact direction and shift symmetry along this direction corresponds to the particle number transformation. This solution can be embedded into string theory by performing a set of operations (known as the Null-Melvin twist) on AdS 5 x S5 solution of type IIB supergravity. This method also provides a way of finding a black hole solution which has asymptotic Schrodinger symmetries. The field theory dual of these gravity solutions happens to be a modified version of DLCQ N = 4 super Yang-Mills theory. The thermodynamics of these theories is very different from that of cold atoms. This happens to be a consequence of realizing the entire Schrodinger group as isometries of the spacetime. We give an example of a holographic realization in which the particle number symmetry is realized as
Energy Technology Data Exchange (ETDEWEB)
Straumann, Norbert [Zuerich Univ. (Switzerland). Inst. fuer Theoretische Physik
2013-02-01
The following topics are dealt with: Matter waves and Schroedinger equation, the statistical interpretation of the wave function, uncertainty relations and measuring process, the formal principles of quantum mechanics, angular momentum and particles with spin, perturbation theory and applications, many-electron systems, scattering theory, quantum chemistry, time dependent perturbation theory, fundamental problems of quantum mechanics. (HSI)
Non-relativistic supergravity in three space-time dimensions
Zojer, Thomas
2016-01-01
This year Einstein's theory of general relativity celebrates its one hundredth birthday. It supersedes the non-relativistic Newtonian theory of gravity in two aspects: i) there is a limiting velocity, nothing can move quicker than the speed of light and ii) the theory is valid in arbitrary
Höfener, Sebastian; Ahlrichs, Reinhart; Knecht, Stefan; Visscher, Lucas
2012-12-07
We report results of non-relativistic and two-component relativistic single-reference coupled-cluster with single and double and perturbative triple excitations [CCSD(T)] treatments for the 4p-block dimers Ga(2) to Br(2) , the 5p-block dimers In(2) to I(2) , and their atoms. Extended basis sets up to pentuple zeta are employed and energies extrapolated to the complete basis-set limit. Relativistic and non-relativistic results for the dissociation energy D(e) are in close agreement with each other and previously published data, provided non-relativistic or scalar-relativistic results are corrected for spin-orbit contributions taken from the literature. An exception is Te(2) where theoretical results scatter by 0.085 eV. By virtue of this agreement it is unexpected that comparison with the experimental D(0) or D(e) dissociation energies (zero-point vibrational effects are negligible in this context) reveal errors larger than 0.1 eV for Ga(2), Ge(2), and Sb(2). Only relativistic treatments are presented for the 6p-block cases Tl(2) to At(2). Sufficient agreement with experimental data is found only for Pb(2) and Bi(2), the deviation of the computed and experimental D(0) values for Po(2) is again larger than 0.1 eV. Deviations of 0.1 eV between the computed and experimental D(0) values are a major reason for concern and call for additional investigations in both fields to clarify the situation. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Relativistic and non-relativistic studies of nuclear matter
Banerjee, MK; Tjon, JA
2002-01-01
We point out that the differences between the results of the non-relativistic lowest order Brueckner theory (LOBT) and the relativistic Dirac-Brueckner analysis predominantly arise from two sources. Besides effects from a nucleon mass modification M* in nuclear medium we have in a relativistic
Study of the equations of a particle in Non- Relativistic Quantum Mechanics
Energy Technology Data Exchange (ETDEWEB)
Miltao, Milton Souza Ribeiro; Silva, Vanessa Santos Teles da [Universidade Estadual de Feira de Santana (UEFS), BA (Brazil)
2011-07-01
Full text: The study of group theory is relevant to the treatment of physical problems, in which concepts of invariance and symmetry are important. In the field of Non-Relativistic Quantum Mechanics, we can do algebraic considerations taking into account the principles of symmetry, considering the framework of the study of Galileo transformations, which have characteristics of group. Therefore, we discuss the Stern-Gerlach experiment that had the historical importance of demonstrating that the electron has an intrinsic angular momentum. Through discussion of this experiment, we found that the spin appears in Non-Relativistic Quantum Mechanics as a feature of the algebraic structure underlying any physical theory represented by a group. From these studies, we have algebraic considerations for physical systems in non-relativistic domain, which are described by the Schroedinger and Pauli equations, describing the dynamics of particles of spin zero and 1/2 respectively, taking into account the structure of the transformations Galileo. Due to the operatorial, we represent Galileo's transformations by matrices by choosing an appropriate basis of space-time. Using these arrays, we saw group characteristics associated with these transformations, which we call the Galileo Group. We note the invariance of the Schroedinger and Pauli equations after these changes, as well as the physical state associated with it, which is represented by a radius vector in Hilbert space. (author)
Symmetries and couplings of non-relativistic electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Festuccia, Guido [Department of Physics and Astronomy, Uppsala University,Lägerhyddsvägen 1, Uppsala (Sweden); Hansen, Dennis [The Niels Bohr Institute, Copenhagen University,Blegdamsvej 17, Copenhagen Ø, DK-2100 (Denmark); Hartong, Jelle [Physique Théorique et Mathématique and International Solvay Institutes,Université Libre de Bruxelles, C.P. 231, Brussels, 1050 (Belgium); Obers, Niels A. [The Niels Bohr Institute, Copenhagen University,Blegdamsvej 17, Copenhagen Ø, DK-2100 (Denmark)
2016-11-08
We examine three versions of non-relativistic electrodynamics, known as the electric and magnetic limit theories of Maxwell’s equations and Galilean electrodynamics (GED) which is the off-shell non-relativistic limit of Maxwell plus a free scalar field. For each of these three cases we study the couplings to non-relativistic dynamical charged matter (point particles and charged complex scalars). The GED theory contains besides the electric and magnetic potentials a so-called mass potential making the mass parameter a local function. The electric and magnetic limit theories can be coupled to twistless torsional Newton-Cartan geometry while GED can be coupled to an arbitrary torsional Newton-Cartan background. The global symmetries of the electric and magnetic limit theories on flat space consist in any dimension of the infinite dimensional Galilean conformal algebra and a U(1) current algebra. For the on-shell GED theory this symmetry is reduced but still infinite dimensional, while off-shell only the Galilei algebra plus two dilatations remain. Hence one can scale time and space independently, allowing Lifshitz scale symmetries for any value of the critical exponent z.
Non-relativistic scalar field on the quantum plane
International Nuclear Information System (INIS)
Jahan, A.
2005-01-01
We apply the coherent state approach to the non-commutative plane to check the one-loop finiteness of the two-point and four-point functions of a non-relativistic scalar field theory in 2+1 dimensions. We show that the two-point and four-point functions of the model are finite at one-loop level and one recovers the divergent behavior of the model in the limit θ->0 + by appropriate redefinition of the non-commutativity parameter
Scattering of Non-Relativistic Charged Particles by Electromagnetic Radiation
Apostol, M.
2017-11-01
The cross-section is computed for non-relativistic charged particles (like electrons and ions) scattered by electromagnetic radiation confined to a finite region (like the focal region of optical laser beams). The cross-section exhibits maxima at scattering angles given by the energy and momentum conservation in multi-photon absorption or emission processes. For convenience, a potential scattering is included and a comparison is made with the well-known Kroll-Watson scattering formula. The scattering process addressed in this paper is distinct from the process dealt with in previous studies, where the scattering is immersed in the radiation field.
Supersymmetric solutions for non-relativistic holography
International Nuclear Information System (INIS)
Donos, Aristomenis; Gauntlett, Jerome P.
2009-01-01
We construct families of supersymmetric solutions of type IIB and D=11 supergravity that are invariant under the non-relativistic conformal algebra for various values of dynamical exponent z≥4 and z≥3, respectively. The solutions are based on five- and seven-dimensional Sasaki-Einstein manifolds and generalise the known solutions with dynamical exponent z=4 for the type IIB case and z=3 for the D=11 case, respectively. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Cobut, V.; Frongillo, Y.; Jay-Gerin, J.P. (Sherbrooke Univ., PQ (Canada)); Patau, J.P. (Toulouse-3 Univ., 31 (France))
1993-04-01
The ingredients and the results of our Monte Carlo simulation of the slowing down of nonrelativistic electrons in irradiated liquid water and of the evolution of the created species are presented. The proportion of excited and ionized species can be seen in the calculated yields at 10[sup -15] s. A fast reorganization of the medium allows radicals and molecular products to be formed and their yields at 10[sup -12] are calculated. Yields of 5.3 electrons and 6.0 hydroxyl radicals per 100 eV absorbed energy are compatible with experimental values at 30 and 200 picoseconds.
Differential regularization of a non-relativistic anyon model
International Nuclear Information System (INIS)
Freedman, D.Z.; Rius, N.
1993-07-01
Differential regularization is applied to a field theory of a non-relativistic charged boson field φ with λ(φ * φ) 2 self-interaction and coupling to a statistics-changing 0(1) Chern-Simons gauge field. Renormalized configuration-space amplitudes for all diagrams contributing to the φ * φ * φφ 4-point function, which is the only primitively divergent Green's function, are obtained up to 3-loop order. The renormalization group equations are explicitly checked, and the scheme dependence of the β-function is investigated. If the renormalization scheme is fixed to agree with a previous 1-loop calculation, the 2- and 3-loop contributions to β(λ, e) vanish, and β(λ, ε) itself vanishes when the ''self-dual'' condition relating λ to the gauge coupling e is imposed. (author). 12 refs, 1 fig
Intense non-relativistic cesium ion beam
International Nuclear Information System (INIS)
Lampel, M.C.
1984-02-01
The Heavy Ion Fusion group at Lawrence Berkeley Laboratory has constructed the One Ampere Cesium Injector as a proof of principle source to supply an induction linac with a high charge density and high brightness ion beam. This is studied here. An electron beam probe was developed as the major diagnostic tool for characterizing ion beam space charge. Electron beam probe data inversion is accomplished with the EBEAM code and a parametrically adjusted model radial charge distribution. The longitudinal charge distribution was not derived, although it is possible to do so. The radial charge distribution that is derived reveals an unexpected halo of trapped electrons surrounding the ion beam. A charge fluid theory of the effect of finite electron temperature on the focusing of neutralized ion beams (Nucl. Fus. 21, 529 (1981)) is applied to the problem of the Cesium beam final focus at the end of the injector. It is shown that the theory's predictions and assumptions are consistent with the experimental data, and that it accounts for the observed ion beam radius of approx. 5 cm, and the electron halo, including the determination of an electron Debye length of approx. 10 cm
Quantum electronics basic theory
Fain, V M; Sanders, J H
1969-01-01
Quantum Electronics, Volume 1: Basic Theory is a condensed and generalized description of the many research and rapid progress done on the subject. It is translated from the Russian language. The volume describes the basic theory of quantum electronics, and shows how the concepts and equations followed in quantum electronics arise from the basic principles of theoretical physics. The book then briefly discusses the interaction of an electromagnetic field with matter. The text also covers the quantum theory of relaxation process when a quantum system approaches an equilibrium state, and explai
Holographic energy loss in non-relativistic backgrounds
Energy Technology Data Exchange (ETDEWEB)
Atashi, Mahdi; Fadafan, Kazem Bitaghsir; Farahbodnia, Mitra [Shahrood University of Technology, Physics Department, P.O. Box 3619995161, Shahrood (Iran, Islamic Republic of)
2017-03-15
In this paper, we study some aspects of energy loss in non-relativistic theories from holography. We analyze the energy lost by a rotating heavy point particle along a circle of radius l with angular velocity ω in theories with general dynamical exponent z and hyperscaling violation exponent θ. It is shown that this problem provides a novel perspective on the energy loss in such theories. A general computation at zero and finite temperature is done and it is shown how the total energy loss rate depends non-trivially on two characteristic exponents (z,θ). We find that at zero temperature there is a special radius l{sub c} where the energy loss is independent of different values of (θ,z). Also at zero temperature, there is a crossover between a regime in which the energy loss is dominated by the linear drag force and by the radiation because of the acceleration of the rotating particle. We find that the energy loss of the particle decreases by increasing θ and z. We note that, unlike in the zero temperature, there is no special radius l{sub c} at finite temperature case. (orig.)
Sen, Sangita; Shee, Avijit; Mukherjee, Debashis
2018-02-01
The orbital relaxation attendant on ionization is particularly important for the core electron ionization potential (core IP) of molecules. The Unitary Group Adapted State Universal Coupled Cluster (UGA-SUMRCC) theory, recently formulated and implemented by Sen et al. [J. Chem. Phys. 137, 074104 (2012)], is very effective in capturing orbital relaxation accompanying ionization or excitation of both the core and the valence electrons [S. Sen et al., Mol. Phys. 111, 2625 (2013); A. Shee et al., J. Chem. Theory Comput. 9, 2573 (2013)] while preserving the spin-symmetry of the target states and using the neutral closed-shell spatial orbitals of the ground state. Our Ansatz invokes a normal-ordered exponential representation of spin-free cluster-operators. The orbital relaxation induced by a specific set of cluster operators in our Ansatz is good enough to eliminate the need for different sets of orbitals for the ground and the core-ionized states. We call the single configuration state function (CSF) limit of this theory the Unitary Group Adapted Open-Shell Coupled Cluster (UGA-OSCC) theory. The aim of this paper is to comprehensively explore the efficacy of our Ansatz to describe orbital relaxation, using both theoretical analysis and numerical performance. Whenever warranted, we also make appropriate comparisons with other coupled-cluster theories. A physically motivated truncation of the chains of spin-free T-operators is also made possible by the normal-ordering, and the operational resemblance to single reference coupled-cluster theory allows easy implementation. Our test case is the prediction of the 1s core IP of molecules containing a single light- to medium-heavy nucleus and thus, in addition to demonstrating the orbital relaxation, we have addressed the scalar relativistic effects on the accuracy of the IPs by using a hierarchy of spin-free Hamiltonians in conjunction with our theory. Additionally, the contribution of the spin-free component of the two-electron
Floerchinger, Stefan
2014-01-01
For non-relativistic quantum field theory in the few-body limit with instantaneous interactions it is shown within the functional renormalization group formalism that propagators are not renormalized and that the renormalization group equations of one-particle irreducible vertex functions are governed by a hierarchical structure. This hierarchy allows to solve the equations in the n-body sector without knowledge or assumptions about the m-body sectors where m>n.
Condensation for non-relativistic matter in Hořava–Lifshitz gravity
Directory of Open Access Journals (Sweden)
Jiliang Jing
2015-10-01
Full Text Available We study condensation for non-relativistic matter in a Hořava–Lifshitz black hole without the condition of the detailed balance. We show that, for the fixed non-relativistic parameter α2 (or the detailed balance parameter ϵ, it is easier for the scalar hair to form as the parameter ϵ (or α2 becomes larger, but the condensation is not affected by the non-relativistic parameter β2. We also find that the ratio of the gap frequency in conductivity to the critical temperature decreases with the increase of ϵ and α2, but increases with the increase of β2. The ratio can reduce to the Horowitz–Roberts relation ωg/Tc≈8 obtained in the Einstein gravity and Cai's result ωg/Tc≈13 found in a Hořava–Lifshitz gravity with the condition of the detailed balance for the relativistic matter. Especially, we note that the ratio can arrive at the value of the BCS theory ωg/Tc≈3.5 by taking proper values of the parameters.
Search for non-relativistic magnetic monopoles with IceCube
Aartsen, M. G.; Abbasi, R.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Altmann, D.; Arguelles, C.; Arlen, T. C.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Becker Tjus, J.; Becker, K.-H.; Benabderrahmane, M. L.; BenZvi, S.; Berghaus, P.; Berley, D.; Bernardini, E.; Bernhard, A.; Besson, D. Z.; Binder, G.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Brayeur, L.; Bretz, H.-P.; Brown, A. M.; Bruijn, R.; Casey, J.; Casier, M.; Chirkin, D.; Christov, A.; Christy, B.; Clark, K.; Classen, L.; Clevermann, F.; Coenders, S.; Cohen, S.; Cowen, D. F.; Cruz Silva, A. H.; Danninger, M.; Daughhetee, J.; Davis, J. C.; Day, M.; de André, J. P. A. M.; De Clercq, C.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; Dunkman, M.; Eagan, R.; Eberhardt, B.; Eichmann, B.; Eisch, J.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feintzeig, J.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Flis, S.; Franckowiak, A.; Frantzen, K.; Fuchs, T.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Golup, G.; Gonzalez, J. G.; Goodman, J. A.; Góra, D.; Grandmont, D. T.; Grant, D.; Gretskov, P.; Groh, J. C.; Groß, A.; Ha, C.; Haack, C.; Haj Ismail, A.; Hallen, P.; Hallgren, A.; Halzen, F.; Hanson, K.; Hebecker, D.; Heereman, D.; Heinen, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Homeier, A.; Hoshina, K.; Huang, F.; Huelsnitz, W.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobi, E.; Jacobsen, J.; Jagielski, K.; Japaridze, G. S.; Jero, K.; Jlelati, O.; Kaminsky, B.; Kappes, A.; Karg, T.; Karle, A.; Kauer, M.; Kelley, J. L.; Kiryluk, J.; Kläs, J.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Krasberg, M.; Kriesten, A.; Krings, K.; Kroll, G.; Kunnen, J.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Landsman, H.; Larson, M. J.; Lesiak-Bzdak, M.; Leuermann, M.; Leute, J.; Lünemann, J.; Macías, O.; Madsen, J.; Maggi, G.; Maruyama, R.; Mase, K.; Matis, H. S.; McNally, F.; Meagher, K.; Meli, A.; Merck, M.; Meures, T.; Miarecki, S.; Middell, E.; Milke, N.; Miller, J.; Mohrmann, L.; Montaruli, T.; Morse, R.; Nahnhauer, R.; Naumann, U.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke, A.; Odrowski, S.; Olivas, A.; Omairat, A.; O'Murchadha, A.; Palczewski, T.; Paul, L.; Pepper, J. A.; Pérez de los Heros, C.; Pfendner, C.; Pieloth, D.; Pinat, E.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Quinnan, M.; Rädel, L.; Rameez, M.; Rawlins, K.; Redl, P.; Reimann, R.; Resconi, E.; Rhode, W.; Ribordy, M.; Richman, M.; Riedel, B.; Robertson, S.; Rodrigues, J. P.; Rott, C.; Ruhe, T.; Ruzybayev, B.; Ryckbosch, D.; Saba, S. M.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Scheriau, F.; Schmidt, T.; Schmitz, M.; Schoenen, S.; Schöneberg, S.; Schönwald, A.; Schukraft, A.; Schulte, L.; Schulz, O.; Seckel, D.; Sestayo, Y.; Seunarine, S.; Shanidze, R.; Sheremata, C.; Smith, M. W. E.; Soldin, D.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stanisha, N. A.; Stasik, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Strahler, E. A.; Ström, R.; Strotjohann, N. L.; Sullivan, G. W.; Taavola, H.; Taboada, I.; Tamburro, A.; Tepe, A.; Ter-Antonyan, S.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tselengidou, M.; Unger, E.; Usner, M.; Vallecorsa, S.; van Eijndhoven, N.; van Santen, J.; Vehring, M.; Voge, M.; Vraeghe, M.; Walck, C.; Wallraff, M.; Weaver, Ch.; Wellons, M.; Wendt, C.; Westerhoff, S.; Whelan, B. J.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; Ziemann, J.; Zierke, S.; Zoll, M.
2014-07-01
The IceCube Neutrino Observatory is a large Cherenkov detector instrumenting of Antarctic ice. The detector can be used to search for signatures of particle physics beyond the Standard Model. Here, we describe the search for non-relativistic, magnetic monopoles as remnants of the Grand Unified Theory (GUT) era shortly after the Big Bang. Depending on the underlying gauge group these monopoles may catalyze the decay of nucleons via the Rubakov-Callan effect with a cross section suggested to be in the range of to . In IceCube, the Cherenkov light from nucleon decays along the monopole trajectory would produce a characteristic hit pattern. This paper presents the results of an analysis of first data taken from May 2011 until May 2012 with a dedicated slow-particle trigger for DeepCore, a subdetector of IceCube. A second analysis provides better sensitivity for the brightest non-relativistic monopoles using data taken from May 2009 until May 2010. In both analyses no monopole signal was observed. For catalysis cross sections of the flux of non-relativistic GUT monopoles is constrained up to a level of at a 90 % confidence level, which is three orders of magnitude below the Parker bound. The limits assume a dominant decay of the proton into a positron and a neutral pion. These results improve the current best experimental limits by one to two orders of magnitude, for a wide range of assumed speeds and catalysis cross sections.
Classical trajectory in non-relativistic scattering
International Nuclear Information System (INIS)
Williams, A.C.
1978-01-01
With the statistical interpretation of quantum mechanics as a guide, the classical trajectory is incorporated into quantum scattering theory. The Feynman path integral formalism is used as a starting point, and classical transformation theory is applied to the phase of the wave function so derived. This approach is then used to derive an expression for the scattering amplitude for potential scattering. It is found that the amplitude can be expressed in an impact parameter representation similar to the Glauber formalism. Connections are then made to the Glauber approximation and to semiclassical approximations derived from the Feynman path integral formalism. In extending this analysis to projectile-nucleus scattering, an approximation scheme is given with the first term being the same as in Glauber's multiple scattering theory. Higher-order approximations, thus, are found to give corrections to the fixed scatterer form of the impulse approximation inherent in the Glauber theory
Non-relativistic anyons from holography
Directory of Open Access Journals (Sweden)
Niko Jokela
2017-03-01
Full Text Available We study generic types of holographic matter residing in Lifshitz invariant defect field theory as modeled by adding probe D-branes in the bulk black hole spacetime characterized by dynamical exponent z and with hyperscaling violation exponent θ. Our main focus will be on the collective excitations of the dense matter in the presence of an external magnetic field. Constraining the defect field theory to 2+1 dimensions, we will also allow the gauge fields become dynamical and study the properties of a strongly coupled anyonic fluid. We will deduce the universal properties of holographic matter and show that the Einstein relation always holds.
Converting non-relativistic dark matter to radiation
Bringmann, Torsten; Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Walia, Parampreet
2018-01-01
Dark matter in the cosmological concordance model is parameterised by a single number, describing the covariantly conserved energy density of a non-relativistic fluid. Here we test this assumption in a model-independent and conservative way by considering the possibility that, at any point during the cosmological evolution, dark matter may be converted into a non-interacting form of radiation. This scenario encompasses, but is more general than, the cases where dark matter decays or annihilat...
Generic stability of dissipative non-relativistic and relativistic fluids
International Nuclear Information System (INIS)
Ván, Peter
2009-01-01
The linear stability of the homogeneous equilibrium of non-relativistic fluids with mass flux and special relativistic fluids with the absolute value of the energy vector as internal energy is investigated. It is proved that the equilibrium is asymptotically stable in both cases due to purely thermodynamic restrictions; the only requirements are the thermodynamic stability and the non-negativity of the transport coefficients
Search for non-relativistic magnetic monopoles with IceCube
Energy Technology Data Exchange (ETDEWEB)
Aartsen, M.G.; Hill, G.C.; Robertson, S.; Whelan, B.J. [University of Adelaide, School of Chemistry and Physics, Adelaide, SA (Australia); Abbasi, R.; Ahlers, M.; Arguelles, C.; Baker, M.; BenZvi, S.; Chirkin, D.; Day, M.; Desiati, P.; Diaz-Velez, J.C.; Eisch, J.; Fadiran, O.; Feintzeig, J.; Gladstone, L.; Halzen, F.; Hoshina, K.; Jacobsen, J.; Jero, K.; Karle, A.; Kauer, M.; Kelley, J.L.; Kopper, C.; Krasberg, M.; Kurahashi, N.; Landsman, H.; Maruyama, R.; McNally, F.; Merck, M.; Morse, R.; Riedel, B.; Rodrigues, J.P.; Santander, M.; Tobin, M.N.; Toscano, S.; Van Santen, J.; Weaver, C.; Wellons, M.; Wendt, C.; Westerhoff, S.; Whitehorn, N. [University of Wisconsin, Department of Physics and Wisconsin IceCube Particle Astrophysics Center, Madison, WI (United States); Ackermann, M.; Benabderrahmane, M.L.; Berghaus, P.; Bernardini, E.; Bretz, H.P.; Cruz Silva, A.H.; Gluesenkamp, T.; Jacobi, E.; Kaminsky, B.; Karg, T.; Middell, E.; Mohrmann, L.; Nahnhauer, R.; Schoenwald, A.; Shanidze, R.; Spiering, C.; Stoessl, A.; Yanez, J.P. [DESY, Zeuthen (Germany); Adams, J.; Brown, A.M.; Hickford, S.; Macias, O. [University of Canterbury, Department of Physics and Astronomy, Private Bag 4800, Christchurch (New Zealand); Aguilar, J.A.; Christov, A.; Montaruli, T.; Rameez, M.; Vallecorsa, S. [Universite de Geneve, Departement de physique nucleaire et corpusculaire, Geneva (Switzerland); Altmann, D.; Classen, L.; Gora, D.; Kappes, A.; Tselengidou, M. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Erlangen Centre for Astroparticle Physics, Erlangen (Germany); Arlen, T.C.; De Andre, J.P.A.M.; DeYoung, T.; Dunkman, M.; Eagan, R.; Groh, J.C.; Huang, F.; Quinnan, M.; Smith, M.W.E.; Stanisha, N.A.; Tesic, G. [Pennsylvania State University, Department of Physics, University Park, PA (United States); Auffenberg, J.; Bissok, M.; Blumenthal, J.; Gretskov, P.; Haack, C.; Hallen, P.; Heinen, D.; Jagielski, K.; Kriesten, A.; Krings, K.; Leuermann, M.; Paul, L.; Raedel, L.; Reimann, R.; Schoenen, S.; Schukraft, A.; Vehring, M.; Wallraff, M.; Wiebusch, C.H.; Zierke, S. [RWTH Aachen University, III. Physikalisches Institut, Aachen (Germany); Bai, X.; Evenson, P.A.; Gaisser, T.K.; Gonzalez, J.G.; Hussain, S.; Kuwabara, T.; Ruzybayev, B.; Seckel, D.; Stanev, T.; Tamburro, A.; Tilav, S. [University of Delaware, Bartol Research Institute and Department of Physics and Astronomy, Newark, DE (United States); Barwick, S.W.; Yodh, G. [University of California, Department of Physics and Astronomy, Irvine, CA (United States); Baum, V.; Eberhardt, B.; Koepke, L.; Kroll, G.; Luenemann, J.; Sander, H.G.; Schatto, K.; Wiebe, K. [University of Mainz, Institute of Physics, Mainz (Germany); Bay, R.; Filimonov, K.; Price, P.B.; Woschnagg, K. [University of California, Department of Physics, Berkeley, CA (United States); Beatty, J.J. [Ohio State University, Department of Physics and Center for Cosmology and Astro-Particle Physics, Columbus, OH (United States); Ohio State University, Department of Astronomy, Columbus, OH (United States); Becker Tjus, J.; Eichmann, B.; Fedynitch, A.; Saba, S.M.; Schoeneberg, S.; Unger, E. [Ruhr-Universitaet Bochum, Fakultaet fuer Physik and Astronomie, Bochum (Germany); Becker, K.H.; Bindig, D.; Fischer-Wasels, T.; Helbing, K.; Hoffmann, R.; Klaes, J.; Kopper, S.; Naumann, U.; Obertacke, A.; Omairat, A.; Posselt, J.; Soldin, D.; Tepe, A. [University of Wuppertal, Department of Physics, Wuppertal (Germany); Berley, D.; Blaufuss, E.; Christy, B.; Goodman, J.A.; Hellauer, R.; Hoffman, K.D.; Huelsnitz, W.; Meagher, K.; Olivas, A.; Redl, P.; Richman, M.; Schmidt, T.; Sullivan, G.W.; Wissing, H. [University of Maryland, Department of Physics, College Park, MD (United States); Bernhard, A.; Coenders, S.; Gross, A.; Leute, J.; Resconi, E.; Schulz, O.; Sestayo, Y. [T.U. Munich, Garching (Germany); Besson, D.Z. [University of Kansas, Department of Physics and Astronomy, Lawrence, KS (United States); Binder, G.; Gerhardt, L.; Ha, C.; Klein, S.R.; Miarecki, S. [University of California, Department of Physics, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Boersma, D.J.; Botner, O.; Euler, S.; Hallgren, A.; Perez de los Heros, C.; Stroem, R.; Taavola, H. [Uppsala University, Department of Physics and Astronomy, Box 516, Uppsala (Sweden); Bohm, C.; Danninger, M.; Finley, C.; Flis, S.; Hulth, P.O.; Hultqvist, K.; Walck, C.; Wolf, M.; Zoll, M. [Stockholm University, Oskar Klein Centre and Department of Physics, Stockholm (Sweden); Bose, D.; Rott, C. [Sungkyunkwan University, Department of Physics, Suwon (Korea, Republic of); Collaboration: IceCube Collaboration; and others
2014-07-15
The IceCube Neutrino Observatory is a large Cherenkov detector instrumenting 1 km{sup 3} of Antarctic ice. The detector can be used to search for signatures of particle physics beyond the Standard Model. Here, we describe the search for non-relativistic, magnetic monopoles as remnants of the Grand Unified Theory (GUT) era shortly after the Big Bang. Depending on the underlying gauge group these monopoles may catalyze the decay of nucleons via the Rubakov-Callan effect with a cross section suggested to be in the range of 10{sup -27} to 10{sup -21} cm{sup 2}. In IceCube, the Cherenkov light from nucleon decays along the monopole trajectory would produce a characteristic hit pattern. This paper presents the results of an analysis of first data taken from May 2011 until May 2012 with a dedicated slow particle trigger for DeepCore, a subdetector of IceCube. A second analysis provides better sensitivity for the brightest non-relativistic monopoles using data taken from May 2009 until May 2010. In both analyses no monopole signal was observed. For catalysis cross sections of 10{sup -22} (10{sup -24}) cm{sup 2} the flux of non-relativistic GUT monopoles is constrained up to a level of Φ{sub 90} ≤ 10{sup -18} (10{sup -17}) cm{sup -2} s{sup -1} sr{sup -1} at a 90 % confidence level, which is three orders of magnitude below the Parker bound. The limits assume a dominant decay of the proton into a positron and a neutral pion. These results improve the current best experimental limits by one to two orders of magnitude, for a wide range of assumed speeds and catalysis cross sections. (orig.)
International Nuclear Information System (INIS)
Woesler, Richard
2007-01-01
The computations of the present text with non-relativistic quantum teleportation equations and special relativity are totally speculative, physically correct computations can be done using quantum field theory, which remain to be done in future. Proposals for what might be called statistical time loop experiments with, e.g., photon polarization states are described when assuming the simplified non-relativistic quantum teleportation equations and special relativity. However, a closed time loop would usually not occur due to phase incompatibilities of the quantum states. Histories with such phase incompatibilities are called inconsistent ones in the present text, and it is assumed that only consistent histories would occur. This is called an exclusion principle for inconsistent histories, and it would yield that probabilities for certain measurement results change. Extended multiple parallel experiments are proposed to use this statistically for transmission of classical information over distances, and regarding time. Experiments might be testable in near future. However, first a deeper analysis, including quantum field theory, remains to be done in future
Dark matter directional detection in non-relativistic effective theories
International Nuclear Information System (INIS)
Catena, Riccardo
2015-01-01
We extend the formalism of dark matter directional detection to arbitrary one-body dark matter-nucleon interactions. The new theoretical framework generalizes the one currently used, which is based on 2 types of dark matter-nucleon interaction only. It includes 14 dark matter-nucleon interaction operators, 8 isotope-dependent nuclear response functions, and the Radon transform of the first 2 moments of the dark matter velocity distribution. We calculate the recoil energy spectra at dark matter directional detectors made of CF 4 , CS 2 and 3 He for the 14 dark matter-nucleon interactions, using nuclear response functions recently obtained through numerical nuclear structure calculations. We highlight the new features of the proposed theoretical framework, and present our results for a spherical dark matter halo and for a stream of dark matter particles. This study lays the foundations for model independent analyses of dark matter directional detection experiments
Some questions in non-relativistic quantum scattering theory
International Nuclear Information System (INIS)
Amrein, W.O.
1974-01-01
This paper is mainly concerned with two problems: Is the set of scattering states identical with the subspace of absolute continuity of the Hamiltonian, H; and In what sense do the scattering states become free as t→+-infinity. Can one define wave operators. Other mathmatical problems are: Asymptotic behavior of momentum observables in the Heisenberg picture, asymptotic completeness of the wave operators, and unitarity of the scattering operator. (G.T.H.)
Non-relativistic Bondi-Metzner-Sachs algebra
Batlle, Carles; Delmastro, Diego; Gomis, Joaquim
2017-09-01
We construct two possible candidates for non-relativistic bms4 algebra in four space-time dimensions by contracting the original relativistic bms4 algebra. bms4 algebra is infinite-dimensional and it contains the generators of the Poincaré algebra, together with the so-called super-translations. Similarly, the proposed nrbms4 algebras can be regarded as two infinite-dimensional extensions of the Bargmann algebra. We also study a canonical realization of one of these algebras in terms of the Fourier modes of a free Schrödinger field, mimicking the canonical realization of relativistic bms4 algebra using a free Klein-Gordon field.
A unified treatment of the non-relativistic and relativistic hydrogen atom: Pt. 3
International Nuclear Information System (INIS)
Swainson, R.A.; Drake, G.W.F.
1991-01-01
This is the last in a series of three papers in which it is shown how the radial part of non-relativistic and relativistic hydrogenic bound-state calculations involving the Green functions can be presented in a unified manner. The work presented here is concerned with the reduced Green functions which arise in second-order stationary state perturbation theory. Using a simple-linear transformation of the four radical parts of the relativistic reduced Green function it is shown how the non-relativistic and relativistic functions are special instances of the solution of a general second-order differential equation. The general solution of this equation is exhibited in the form of a Sturmian expansion, and complete solutions in both cases are presented. Recursion relations are deduced for the radial parts of both reduced Green functions and their matrix elements are examined in detail. As a test of the given functions the second-order effect of a perturbation of the nuclear charge is calculated and is shown to agree exactly with the value expected from a simple Taylor expansion of the hydrogenic energy formula. (author)
Non-relativistic spinning particle in a Newton-Cartan background
Barducci, Andrea; Casalbuoni, Roberto; Gomis, Joaquim
2018-01-01
We construct the action of a non-relativistic spinning particle moving in a general torsionless Newton-Cartan background. The particle does not follow the geodesic equations, instead the motion is governed by the non-relativistic analog of Papapetrou equation. The spinning particle is described in terms of Grassmann variables. In the flat case the action is invariant under the non-relativistic analog of space-time vector supersymmetry.
Statistical theory of electron densities
International Nuclear Information System (INIS)
Pratt, L.R.; Hoffman, G.G.; Harris, R.A.
1988-01-01
An optimized Thomas--Fermi theory is proposed which retains the simplicity of the original theory and is a suitable reference theory for Monte Carlo density functional treatments of condensed materials. The key ingredient of the optimized theory is a neighborhood sampled potential which contains effects of the inhomogeneities in the one-electron potential. In contrast to the traditional Thomas--Fermi approach, the optimized theory predicts a finite electron density in the vicinity of a nucleus. Consideration of the example of an ideal electron gas subject to a central Coulomb field indicates that implementation of the approach is straightforward. The optimized theory is found to fail completely when a classically forbidden region is approached. However, these circumstances are not of primary interest for calculations of interatomic forces. It is shown how the energy functional of the density may be constructed by integration of a generalized Hellmann--Feynman relation. This generalized Hellmann--Feynman relation proves to be equivalent to the variational principle of density functional quantum mechanics, and, therefore, the present density theory can be viewed as a variational consequence of the constructed energy functional
The incompressible non-relativistic Navier-Stokes equation from gravity
International Nuclear Information System (INIS)
Bhattacharyya, Sayantani; Minwalla, Shiraz; Wadia, Spenta R.
2009-01-01
We note that the equations of relativistic hydrodynamics reduce to the incompressible Navier-Stokes equations in a particular scaling limit. In this limit boundary metric fluctuations of the underlying relativistic system turn into a forcing function identical to the action of a background electromagnetic field on the effectively charged fluid. We demonstrate that special conformal symmetries of the parent relativistic theory descend to 'accelerated boost' symmetries of the Navier-Stokes equations, uncovering a conformal symmetry structure of these equations. Applying our scaling limit to holographically induced fluid dynamics, we find gravity dual descriptions of an arbitrary solution of the forced non-relativistic incompressible Navier-Stokes equations. In the holographic context we also find a simple forced steady state shear solution to the Navier-Stokes equations, and demonstrate that this solution turns unstable at high enough Reynolds numbers, indicating a possible eventual transition to turbulence.
Electronics from theory into practice
Fisher, J E; Hammond, P
1976-01-01
Electronics - From Theory Into Practice deals with design procedures in electronics and bridges the gap between theoretical knowledge and practice. It provides design examples and discusses the use of the Laplace Transform for solving engineering problems. The book introduces bipolar and field effect transistor, the unijunction transistor and the silicon-controlled rectifier, and shows how data sheets are used in design calculations. It then examines the development of integrated circuits and their characteristics. Following this discussion are chapters that contain a brief treatment of theory
International Nuclear Information System (INIS)
Dattoli, G.; Torre, A.
1989-01-01
The essential features of the theory of the free electron laser (FEL) are given in some detail. Beginning with an explanation of the basic gain mechanism, the lectures continue with a discussion of the problems associated with single-passage and recirculated (storage-ring) operation. Pulse propagation effects and the so-called 'lethargic' behaviour are analysed more completely. Finally, elements of FEL quantum theory are reported, in order to clarify the laser process from the microscopic point of view. Appendices give a fuller treatment of optical cavities and undulator magnets. (orig.)
Summary on electron cyclotron theory
International Nuclear Information System (INIS)
Westerhof, E.
2003-01-01
The papers presented within the Theory Sessions of the conference clearly reflect the general trends of the research field. The growing use of Electron Bernstein Waves (EBW) for plasma heating and current drive in overdense plasmas goes hand in hand with an increased theoretical understanding of EBW excitation. While the expanding number of devices with powerful ECRH systems allowing ever more detailed experiments is reflected in the increased detail of modelling and consequent understanding of the experimental results. Apart from these general trends, some more fundamental contributions to the field of electron cyclotron wave propagation are highlighted. (author)
Particle production in high energy collisions and the non-relativistic quark model
International Nuclear Information System (INIS)
Anisovich, V.V.; Nyiri, J.
1981-07-01
The present review deals with multiparticle production processes at high energies using ideas which originate in the non-relativistic quark model. Consequences of the approach are considered and they are compared with experimental data. (author)
Non-relativistic and relativistic quantum kinetic equations in nuclear physics
International Nuclear Information System (INIS)
Botermans, W.M.M.
1989-01-01
In this thesis an attempt is made to draw up a quantummechanical tranport equation for the explicit calculation oof collision processes between two (heavy) ions, by making proper approaches of the exact equations (non-rel.: N-particles Schroedinger equation; rel.: Euler-Lagrange field equations.). An important starting point in the drag-up of the theory is the behaviour of nuclear matter in equilibrium which is determined by individual as well as collective effects. The central point in this theory is the effective interaction between two nucleons both surrounded by other nucleons. In the derivation of the tranport equations use is made of the green's function formalism as developed by Schwinger and Keldys. For the Green's function kinematic equations are drawn up and are solved by choosing a proper factorization of three- and four-particle Green's functions in terms of one- and two-particle Green's functions. The necessary boundary condition is obtained by explicitly making use of Boltzmann's assumption that colliding particles are statistically uncorrelated. Finally a transport equation is obtained in which the mean field as well as the nucleon-nucleon collisions are given by the same (medium dependent) interaction. This interaction is the non-equilibrium extension of the interaction as given in the Brueckner theory of nuclear matter. Together, kinetic equation and interaction, form a self-consistent set of equations for the case of a non-relativistic as well as for the case of a relativistic starting point. (H.W.) 148 refs.; 6 figs.; 411 schemes
A unified treatment of the non-relativistic and relativistic hydrogen atom: Pt. 2
International Nuclear Information System (INIS)
Swainson, R.A.; Drake, G.W.F.
1991-01-01
This is the second in a series of three papers in which it is shown how the radial part of non-relativistic and relativistic hydrogenic bound-state calculations involving the Green functions can be presented in a unified manner. In this paper the non-relativistic Green function is examined in detail; new functional forms are presented and a clear mathematical progression is show to link these and most other known forms. A linear transformation of the four radial parts of the relativistic Green function is given which allows for the presentation of this function as a simple generalization of the non-relativistic Green function. Thus, many properties of the non-relativistic Green function are shown to have simple relativistic generalizations. In particular, new recursion relations of the radial parts of both the non-relativistic and relativistic Green functions are presented, along with new expressions for the double Laplace transforms and recursion relations between the radial matrix elements. (author)
Long, Andrew J.; Lunardini, Cecilia; Sabancilar, Eray
2014-08-01
We study the physics potential of the detection of the Cosmic Neutrino Background via neutrino capture on tritium, taking the proposed PTOLEMY experiment as a case study. With the projected energy resolution of Δ ~ 0.15 eV, the experiment will be sensitive to neutrino masses with degenerate spectrum, m1 simeq m2 simeq m3 = mν gtrsim 0.1 eV. These neutrinos are non-relativistic today; detecting them would be a unique opportunity to probe this unexplored kinematical regime. The signature of neutrino capture is a peak in the electron spectrum that is displaced by 2 mν above the beta decay endpoint. The signal would exceed the background from beta decay if the energy resolution is Δ lesssim 0.7 mν . Interestingly, the total capture rate depends on the origin of the neutrino mass, being ΓD simeq 4 and ΓM simeq 8 events per year (for a 100 g tritium target) for unclustered Dirac and Majorana neutrinos, respectively. An enhancement of the rate of up to Script O(1) is expected due to gravitational clustering, with the unique potential to probe the local overdensity of neutrinos. Turning to more exotic neutrino physics, PTOLEMY could be sensitive to a lepton asymmetry, and reveal the eV-scale sterile neutrino that is favored by short baseline oscillation searches. The experiment would also be sensitive to a neutrino lifetime on the order of the age of the universe and break the degeneracy between neutrino mass and lifetime which affects existing bounds.
Energy Technology Data Exchange (ETDEWEB)
Long, Andrew J.; Lunardini, Cecilia; Sabancilar, Eray, E-mail: andrewjlong@asu.edu, E-mail: Cecilia.Lunardini@asu.edu, E-mail: Eray.Sabancilar@asu.edu [Physics Department, Arizona State University, Tempe, Arizona 85287 (United States)
2014-08-01
We study the physics potential of the detection of the Cosmic Neutrino Background via neutrino capture on tritium, taking the proposed PTOLEMY experiment as a case study. With the projected energy resolution of Δ ∼ 0.15 eV, the experiment will be sensitive to neutrino masses with degenerate spectrum, m{sub 1} ≅ m{sub 2} ≅ m{sub 3} = m{sub ν} ∼> 0.1 eV. These neutrinos are non-relativistic today; detecting them would be a unique opportunity to probe this unexplored kinematical regime. The signature of neutrino capture is a peak in the electron spectrum that is displaced by 2 m{sub ν} above the beta decay endpoint. The signal would exceed the background from beta decay if the energy resolution is Δ ∼< 0.7 m{sub ν} . Interestingly, the total capture rate depends on the origin of the neutrino mass, being Γ{sup D} ≅ 4 and Γ{sup M} ≅ 8 events per year (for a 100 g tritium target) for unclustered Dirac and Majorana neutrinos, respectively. An enhancement of the rate of up to O(1) is expected due to gravitational clustering, with the unique potential to probe the local overdensity of neutrinos. Turning to more exotic neutrino physics, PTOLEMY could be sensitive to a lepton asymmetry, and reveal the eV-scale sterile neutrino that is favored by short baseline oscillation searches. The experiment would also be sensitive to a neutrino lifetime on the order of the age of the universe and break the degeneracy between neutrino mass and lifetime which affects existing bounds.
Infinite stochastic acceleration of charged particles from non-relativistic initial energies
International Nuclear Information System (INIS)
Buts, V.A.; Manujlenko, O.V.; Turkin, Yu.A.
1997-01-01
Stochastic charged particle acceleration by electro-magnetic field due to overlapping of non-linear cyclotron resonances is considered. It was shown that non-relativistic charged particles are involved in infinitive stochastic acceleration regime. This effect can be used for stochastic acceleration or for plasma heating by regular electro-magnetic fields
shape change in Hf, W and Os-isotopes: A non-relativistic Hartree ...
Indian Academy of Sciences (India)
Abstract. We have investigated the ground-state structures of even-even Hf, W and. Os isotopes within the framework of a deformed non-relativistic Hartree-Fock and a rela- tivistic mean field formalism. A majority of the nuclei are predicted to be prolate in shape in the relativistic calculations. On the other hand, contrary to the ...
Non-relativistic and relativistic scattering by short-range potentials
DEFF Research Database (Denmark)
Arnbak, H.; Christiansen, Peter Leth; Gaididei, Yuri Borisovich
2011-01-01
Relativistic and non-relativistic scattering by short-range potentials is investigated for selected problems. Scattering by the δ′ potential in the Schrödinger equation and δ potentials in the Dirac equation must be solved by regularization, efficiently carried out by a perturbation technique...
Non-relativistic and relativistic quantum kinetic equations in nuclear physics.
Botermans, Wilhelmus Martinus Maria
1989-01-01
In this thesis, we discussed the derivation of quantum kinetic equations appropriate for applications in nuclear physics, both in a non-relativistic and in a relativistic context. In each case we obtained a kinetic equation together with an equation for the effective interaction. The latter serves
The Lorentz Theory of Electrons and Einstein's Theory of Relativity
Goldberg, Stanley
1969-01-01
Traces the development of Lorentz's theory of electrons as applied to the problem of the electrodynamics of moving bodies. Presents evidence that the principle of relativity did not play an important role in Lorentz's theory, and that though Lorentz eventually acknowledged Einstein's work, he was unwilling to completely embrace the Einstein…
The confined hydrogenoid ion in non-relativistic quantum electrodynamics
Amour, L
2006-01-01
We consider a system of a nucleus with an electron together with the quantized electromagnetic field. Instead of fixing the nucleus, the system is confined by its center of mass. This model is used in theoretical physics to explain the Lamb-Dicke and the M\\"ossbauer effects (see [CTDRG]). When an ultraviolet cut-off is imposed we initiate the spectral analysis of the Hamiltonian describing the system and we derive the existence of a ground state. This is achieved without conditions on the fine structure constant. [CTDRG] C. Cohen-Tannoudji, J. Dupont-Roc and G. Grynberg. Processus d'interaction entre photons et atomes. Edition du CNRS, 2001.
Theories of the solvated electron
International Nuclear Information System (INIS)
Kestner, N.R.
1987-01-01
In this chapter the authors address only the final state of the electron, that is, the solvated state, which, if no chemical reaction would occur, is a stable entity with well-defined characteristics. Except for some metal-ammonia solutions, and possible a few other cases, such stable species, in reality, exist but a short time (often as short as microseconds). Nevertheless, this chapter only deals with this final time-independent,'' completely solvated,'' equilibrium species. The last statement is added to indicate that the solvent around the electron has also come to thermal equilibrium with the field of the charge
Two theories of auroral electron acceleration
International Nuclear Information System (INIS)
Bryant, D.A.
1990-03-01
Two theories of auroral electron acceleration are discussed. The first is the currently widely held view that the acceleration is an ordered process in a quasi-static electric field. It is suggested that, although there are many factors seeming to support this theory, the major qualifications and uncertainties that have been identified combine to cast serious doubt over its validity. The second is a relatively new interpretation in terms of stochastic acceleration in turbulent electric fields. This second theory, which appears to account readily for most known features of the electron distribution function, is considered to provide a more promising approach to this central question in magnetospheric plasma physics. (author)
Cavity loss factors of non-relativistic beams for Project X
Energy Technology Data Exchange (ETDEWEB)
Lunin, A.; Yakovlev, V.; Kazakov, S.; /Fermilab
2011-03-01
Cavity loss factor calculation is an important part of the total cryolosses estimation for the super conductive (SC) accelerating structures. There are two approaches how to calculate cavity loss factors, the integration of a wake potential over the bunch profile and the addition of loss factors for individual cavity modes. We applied both methods in order to get reliable results for non-relativistic beam. The time domain CST solver was used for a wake potential calculation and the frequency domain HFSS code was used for the cavity eigenmodes spectrum findings. Finally we present the results of cavity loss factors simulations for a non-relativistic part of the ProjectX and analyze it for various beam parameters.
International Nuclear Information System (INIS)
Durmus, Aysen
2011-01-01
We investigate solutions of a non-relativistic wave equation in hyperspherical coordinates for a diatomic molecule system interacting with a generalized Kratzer potential. Rovibrational eigenvalues and corresponding wavefunctions of non-relativistic diatomic molecules have been determined within the framework of the asymptotic iteration method. Certain fundamental conditions for the applications of the asymptotic iteration method, such as a suitable asymptotic form for the wave-function and the termination condition for the iteration process, are discussed. N-dimensional bound state eigenfunction solutions used in studying the dynamical variables of diatomic molecules are obtained in terms of a confluent hypergeometric function and a generalized Laguerre polynomial. This systematic approach is tested by calculating the rovibrational energy spectra of hydrogen and sodium chloride molecules.
Non-relativistic model for interaction of dark particles with matter
Takibayev, Nurgali
2014-01-01
A non-relativistic quantum mechanical model for interaction of dark particles with matter is proposed; the model describes resonant amplification of effective interaction between two massive bodies at large distances between them. The phenomenon is explained by catalytic action by a third dark particle scattered at a system of two heavy bodies. It is shown that effective interaction between the heavy bodies is changed at large distances and can transform into repulsion contributing in that ca...
Spin force and torque in non-relativistic Dirac oscillator on a sphere
Shikakhwa, M. S.
2018-03-01
The spin force operator on a non-relativistic Dirac oscillator (in the non-relativistic limit the Dirac oscillator is a spin one-half 3D harmonic oscillator with strong spin-orbit interaction) is derived using the Heisenberg equations of motion and is seen to be formally similar to the force by the electromagnetic field on a moving charged particle. When confined to a sphere of radius R, it is shown that the Hamiltonian of this non-relativistic oscillator can be expressed as a mere kinetic energy operator with an anomalous part. As a result, the power by the spin force and torque operators in this case are seen to vanish. The spin force operator on the sphere is calculated explicitly and its torque is shown to be equal to the rate of change of the kinetic orbital angular momentum operator, again with an anomalous part. This, along with the conservation of the total angular momentum, suggests that the spin force exerts a spin-dependent torque on the kinetic orbital angular momentum operator in order to conserve total angular momentum. The presence of an anomalous spin part in the kinetic orbital angular momentum operator gives rise to an oscillatory behavior similar to the Zitterbewegung. It is suggested that the underlying physics that gives rise to the spin force and the Zitterbewegung is one and the same in NRDO and in systems that manifest spin Hall effect.
A unified treatment of the non-relativistic and relativistic hydrogen atom: Pt. 1
International Nuclear Information System (INIS)
Swainson, R.A.; Drake, G.W.F.
1991-01-01
In this and the following two papers in this series it is shown how the radial part of non-relativistic and relativistic hydrogenic bound-state calculations involving the Green functions can be presented in a unified manner. The angular part of such calculations, being well understood, is performed in the standard way. In this, the first paper, it is shown how a suitable linear transformation of the two relativistic radial wavefunctions allows the pair of relativistic coupled differential equations to be written as two uncoupled second-order equations which are simple generalizations of the corresponding non-relativistic equation. This transformation is presented in a manner which allows for a simple extension to the Green function problem. The transformed relativistic wavefunctions are explicitly derived and the normalization is presented in a novel and simple way. A new derivation is given for the recursion relations for both non-relativistic and relativistic radial wavefunctions, some of which are new. These relations are required in the subsequent papers. (author)
Electron-electron scattering in the Weinberg-Salam theory
International Nuclear Information System (INIS)
Hirashima, Hideharu
1988-01-01
The Weinberg theory is generally believed to have been established in recent years. At distances smaller than 10 -16 cm, the strength of weak interactions becomes almost equal to that of the electromagnetic interactions. The grand unified theories proposed so far are based on the idea that the coupling constants for the Abelian U(1) field, the non-Abelian SU(2) field and the non-Abelian SU(3) color field depend on momentum transfer, or distance. At distances smaller than 10 -29 cm, weak electromagnetic and strong interactions are assumed to become almost the same strength. The question here is whether nature has no new features in the vast range from 10 -16 cm (10 2 GeV) to 10 -29 cm (10 15 GeV) and whether the substructure of quark or lepton can be expected to be revealed at the next accelerator energy region. The Weinberger-Salam theory may lose its validity even in near future experiments. In any case, it must be overhauled from various aspects. From this point of view, by using the Weinberger-Salam theory, calculation of the differential cross section for elastic electron-electron scattering is re-examined to make clear the difference with the results of QED. In addition, as an example of experiments which could investigate the Weinberger-Salam theory more in detail, a short account is given of the elastic scattering of polarized electrons from a polarized electron target. (Nogami, K.)
Theory of the Electron Sheath and Presheath
Scheiner, Brett; Baalrud, Scott; Yee, Benjamin; Hopkins, Matthew; Barnat, Edward
2015-09-01
Electron sheaths are commonly found near Langmuir probes collecting the electron saturation current. The common assumption is that the probe collects the random flux of electrons incident on the sheath, which tacitly implies that there is no electron presheath and that the flux collected is due to a velocity space truncation of the velocity distribution function (VDF). This work provides a dedicated theory of electron sheaths, which suggests that electron sheaths are not so simple. Motivated by VDFs observed in recent Particle-In-Cell (PIC) simulations, we develop a 1D model for the electron sheath and presheath. In the model, under low temperature plasma conditions, an electron pressure gradient accelerates electrons in the presheath to a flow velocity that exceeds the electron thermal speed at the sheath edge. This pressure gradient allows the generation of large flows compared to those that would be generated by the electric field alone. It is due to this pressure gradient that the electron presheath extends much further into the plasma (nominally by a factor of √{mi /me }) than an analogous ion presheath. Results of the model are compared with PIC simulations. This work was supported by the Office of Fusion Energy Science at the U.S. Department of Energy under contract DE-AC04-94SL85000 and by the Office of Science Graduate Student Research (SCGSR) program under Contract Number DE-AC05-06OR23100.
Kinetic theory of free electron lasers
Energy Technology Data Exchange (ETDEWEB)
Hafizi, B. [Naval Research Lab., Washington, DC (United States); Roberson, C.W. [Office of Naval Research, Arlington, VA (United States)
1995-12-31
We have developed a relativistic kinetic theory of free electron lasers (FELs). The growth rate, efficiency, filling factor and radius of curvature of the radiation wave fronts are determined. We have used the theory to examine the effects of beam compression on growth rate. The theory has been extended to include self field effects on FEL operation. These effects are particularly important in compact, low voltage FELs. The surprising result is that the self field contribution to the beam quality is opposite to the emittance contribution. Hence self fields can improve beam quality, particularly in compact, low voltage FELs.
Paramagnetic form factors from itinerant electron theory
International Nuclear Information System (INIS)
Cooke, J.F.; Liu, S.H.; Liu, A.J.
1985-01-01
Elastic neutron scattering experiments performed over the past two decades have provided accurate information about the magnetic form factors of paramagnetic transition metals. These measurements have traditionally been analyzed in terms of an atomic-like theory. There are, however, some cases where this procedure does not work, and there remains the overall conceptual problem of using an atomistic theory for systems where the unpaired-spin electrons are itinerant. We have recently developed computer codes for efficiently evaluating the induced magnetic form factors of fcc and bcc itinerant electron paramagnets. Results for the orbital and spin contributions have been obtained for Cr, Nb, V, Mo, Pd, and Rh based on local density bands. By using calculated spin enhancement parameters, we find reasonable agreement between theory and neutron form factor data. In addition, these zero parameter calculations yield predictions for the bulk susceptibility on an absolute scale which are in reasonable agreement with experiment in all treated cases except palladium
Non-relativistic AdS branes and Newton-Hooke superalgebra
International Nuclear Information System (INIS)
Sakaguchi, Makoto; Yoshida, Kentaroh
2006-01-01
We examine a non-relativistic limit of D-branes in AdS 5 x S 5 and M-branes in AdS 4/7 x S 7/4 . First, Newton-Hooke superalgebras for the AdS branes are derived from AdS x S superalgebras as Inoenue-Wigner contractions. It is shown that the directions along which the AdS-brane worldvolume extends are restricted by requiring that the isometry on the AdS-brane worldvolume and the Lorentz symmetry in the transverse space naturally extend to the super-isometry. We also derive Newton-Hooke superalgebras for pp-wave branes and show that the directions along which a brane worldvolume extends are restricted. Then the Wess-Zumino terms of the AdS branes are derived by using the Chevalley-Eilenberg cohomology on the super-AdS x S algebra, and the non-relativistic limit of the AdS-brane actions is considered. We show that the consistent limit is possible for the following branes: Dp (even,even) for p = 1 mod 4 and Dp (odd,odd) for p = 3 mod 4 in AdS 5 x S 5 , and M2 (0,3), M2 (2,1), M5 (1,5) and M5 (3,3) in AdS 4 x S 7 and S 4 x AdS 7 . We furthermore present non-relativistic actions for the AdS branes
Analog Electronic Filters Theory, Design and Synthesis
Dimopoulos, Hercules G
2012-01-01
Filters are essential subsystems in a huge variety of electronic systems. Filter applications are innumerable; they are used for noise reduction, demodulation, signal detection, multiplexing, sampling, sound and speech processing, transmission line equalization and image processing, to name just a few. In practice, no electronic system can exist without filters. They can be found in everything from power supplies to mobile phones and hard disk drives and from loudspeakers and MP3 players to home cinema systems and broadband Internet connections. This textbook introduces basic concepts and methods and the associated mathematical and computational tools employed in electronic filter theory, synthesis and design. This book can be used as an integral part of undergraduate courses on analog electronic filters. Includes numerous, solved examples, applied examples and exercises for each chapter. Includes detailed coverage of active and passive filters in an independent but correlated manner. Emphasizes real filter...
X-versus y-scaling in non-relativistic deep inelastic scattering
International Nuclear Information System (INIS)
Santos Padula, S. dos; Escobar, C.O.
1983-01-01
It is shown, in the context of non-relativistic potential scattering, that the appropriate scaling variable for the deep inelastic region is not the usual Bjorken one x sub(Bj) = Q 2 /2 Mν but instead, the variable y=(2mν-q 2 sup(→))/2q. The y-scaling is shown to be obtained in a natural way by using the WKB approximation. Numerical results are presented comparing the approach to scaling in terms of x sub(Bj) and y. (Author) [pt
Spin rotation function in a microscopic non-relativistic optical model
International Nuclear Information System (INIS)
Bauhoff, W.
1984-01-01
A microscopic optical potential, which is calculated non-relativistically with a density-dependent effective force, is used to calculate cross-section, polarization and spin-rotation function for elastic proton scattering from 40 Ca at 160 MeV and 497 MeV. At 160 MeV, the agreement to the data is comparable to phenomenological fits, and the spin-rotation can be used to distinguish between microscopic and Woods-Saxon potentials. A good fit to the spin-rotation function results at 497 MeV, whereas the polarization data are not well reproduced
Hadron spectra from a non-relativistic model with confining harmonic potential
Directory of Open Access Journals (Sweden)
Cuervo-Reyes Eduardo
2003-01-01
Full Text Available Hadron spectra and other properties of quark systems are studied in the framework of a non-relativistic spinindependent phenomenological model. The chosen confining potential is harmonic, which allowed us to obtain analytical solutions for both meson and baryon (of equal constituent quarks spectra. The introduced parameters are fixed from the low-lying levels of heavy quark mesons. The requirement of flavor independence is imposed, and it restricts the possible choices of inter-quark potentials. The hyper-spherical coordinates are considered for the solution of the three-body problem.
Development of the doppler electron velocimeter: theory.
Energy Technology Data Exchange (ETDEWEB)
Reu, Phillip L.
2007-03-01
Measurement of dynamic events at the nano-scale is currently impossible. This paper presents the theoretical underpinnings of a method for making these measurements using electron microscopes. Building on the work of Moellenstedt and Lichte who demonstrated Doppler shifting of an electron beam with a moving electron mirror, further work is proposed to perfect and utilize this concept in dynamic measurements. Specifically, using the concept of ''fringe-counting'' with the current principles of transmission electron holography, an extension of these methods to dynamic measurements is proposed. A presentation of the theory of Doppler electron wave shifting is given, starting from the development of the de Broglie wave, up through the equations describing interference effects and Doppler shifting in electron waves. A mathematical demonstration that Doppler shifting is identical to the conceptually easier to understand idea of counting moving fringes is given by analogy to optical interferometry. Finally, potential developmental experiments and uses of a Doppler electron microscope are discussed.
Interacting electrons theory and computational approaches
Martin, Richard M; Ceperley, David M
2016-01-01
Recent progress in the theory and computation of electronic structure is bringing an unprecedented level of capability for research. Many-body methods are becoming essential tools vital for quantitative calculations and understanding materials phenomena in physics, chemistry, materials science and other fields. This book provides a unified exposition of the most-used tools: many-body perturbation theory, dynamical mean field theory and quantum Monte Carlo simulations. Each topic is introduced with a less technical overview for a broad readership, followed by in-depth descriptions and mathematical formulation. Practical guidelines, illustrations and exercises are chosen to enable readers to appreciate the complementary approaches, their relationships, and the advantages and disadvantages of each method. This book is designed for graduate students and researchers who want to use and understand these advanced computational tools, get a broad overview, and acquire a basis for participating in new developments.
Electron Correlations in Local Effective Potential Theory
Directory of Open Access Journals (Sweden)
Viraht Sahni
2016-08-01
Full Text Available Local effective potential theory, both stationary-state and time-dependent, constitutes the mapping from a system of electrons in an external field to one of the noninteracting fermions possessing the same basic variable such as the density, thereby enabling the determination of the energy and other properties of the electronic system. This paper is a description via Quantal Density Functional Theory (QDFT of the electron correlations that must be accounted for in such a mapping. It is proved through QDFT that independent of the form of external field, (a it is possible to map to a model system possessing all the basic variables; and that (b with the requirement that the model fermions are subject to the same external fields, the only correlations that must be considered are those due to the Pauli exclusion principle, Coulomb repulsion, and Correlation–Kinetic effects. The cases of both a static and time-dependent electromagnetic field, for which the basic variables are the density and physical current density, are considered. The examples of solely an external electrostatic or time-dependent electric field constitute special cases. An efficacious unification in terms of electron correlations, independent of the type of external field, is thereby achieved. The mapping is explicated for the example of a quantum dot in a magnetostatic field, and for a quantum dot in a magnetostatic and time-dependent electric field.
Postmodern theories about readers in electronic environment
Directory of Open Access Journals (Sweden)
Ivanka Kuić
2015-03-01
Full Text Available Introductory part of the paper discusses theories about readers in the last decades of the 20th century. In particular, two big theoretical schools are discussed: aesthetic reception theory and reader-response-criticism movement. Readers are a subject of very different scientific disciplines: literature theory, sociology, anthropology, book history and library science. The idea that a reader is an essential subject for future life of a literary work is common to all theorists. By constructing the theory about a reader, theorists have thought about the reader who uses the conventions of printed text. The issue whether these concepts correspond to electronic surroundings is discussed. Characteristics of the hypertext are emphasized as a new paradigm, and also the issue weather readers enjoys in hypertextual fiction. In conclusion, paper expands the virtual dimension of Isers's theory about interaction between the text and the reader, and also Fish's concept of “interpretative community” which may be constituted on the Internet as a flexible virtual community.
Energy Technology Data Exchange (ETDEWEB)
Keim, M.
2005-07-01
In the present thesis response effects in interatomic collisions with two active electrons are studied in the range of non-relativistic collision energies. The starting point is the mapping of the time-dependent interacting many-electron sytem on an effective one-particle picture on the base of the time-dependent density functional theory (TDDFT). By means of the basis generator method the one-particle equations aring in the framework of the TDDFT concept are solved in a finite-dimensional model space. In the study of ionization cross section in the collisional systeem anti p+He it is shown that by response effects an essential diminuishing of the cross sections in comparison to the no-response case is reached. Analoguously the ionization cross sections for the collisional systems p-He, He{sup 2+}-He, Li{sup 3+}-He and p-Li{sup +} behave.
Zhu, X. P.; Zhang, Z. C.; Pushkarev, A. I.; Lei, M. K.
2016-01-01
High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200-300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.
Energy Technology Data Exchange (ETDEWEB)
Zhu, X. P. [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024 (China); Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Zhang, Z. C.; Lei, M. K., E-mail: surfeng@dlut.edu.cn [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Pushkarev, A. I. [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Laboratory of Beam and Plasma Technology, High Technologies Physics Institute, Tomsk Polytechnic University, 30, Lenin Ave, 634050 Tomsk (Russian Federation)
2016-01-15
High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200–300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.
AdS and dS black hole solutions in analogue gravity: The relativistic and non-relativistic cases
Dey, Ramit; Liberati, Stefano; Turcati, Rodrigo
2016-01-01
We show that Schwarzschild black hole solutions in asymptotically Anti-de Sitter (AdS) and de Sitter (dS) spaces may, up to a conformal factor, be reproduced in the framework of analogue gravity. The aforementioned derivation is performed using relativistic and non-relativistic Bose-Einstein condensates. In addition, we demonstrate that the (2+1) planar AdS black hole can be mapped into the non-relativistic acoustic metric. Given that AdS black holes are extensively employed in the gauge/grav...
Duality of two-point functions for confined non-relativistic quark-antiquark systems
International Nuclear Information System (INIS)
Fishbane, P.M.; Gasiorowicz, S.G.; Kaus, P.
1985-01-01
An analog to the scattering matrix describes the spectrum and high-energy behavior of confined systems. We show that for non-relativistic systems this S-matrix is identical to a two-point function which transparently describes the bound states for all angular momenta. Confined systems can thus be described in a dual fashion. This result makes it possible to study the modification of linear trajectories (originating in a long-range confining potential) due to short range forces which are unknown except for the way in which they modify the asymptotic behavior of the two point function. A type of effective range expansion is one way to calculate the energy shifts. 9 refs
Bond centred functions in relativistic and non-relativistic calculations for diatomics
International Nuclear Information System (INIS)
Matito, Eduard; Kobus, Jacek; Styszynski, Jacek
2006-01-01
In this paper, we discuss the performance of molecular basis sets consisting of atomic centred (AC) functions augmented with bond centred (BC) functions in relativistic and non-relativistic calculations carried out at the Hartree-Fock and several correlated levels of approximation. While usually non-correlated calculations employing BC functions can be performed at a lower computational cost as compared with those making use of energy optimized AC basis sets, the correlated calculations are always more accurate and less expensive with the latter. It is demonstrated that both correlated or non-correlated calculations always benefit from the addition of a few BC functions with a moderate increase of computational effort. The performance of basis sets containing even-tempered BC functions is also studied and their usage is advocated in case of relativistic calculations
Electron band theory 1952-1962
International Nuclear Information System (INIS)
Lomer, W.M.
1980-01-01
Work undertaken by the Theoretical Physics Division between 1952 and 1965 to obtain an understanding of electrons in metals, with uranium and the actinides and the structurally-important transition metals as the main targets is examined. A main result of that period was a conviction that the majority of the physical properties of all metals, except the 4f rare-earth series and the actinides beyond uranium, were dominated by band effects which could be described well enough for most purposes by simple one-electron calculations with simple self-consistent fields. The period from 1960 on showed increasingly clearly the necessity of incorporating relativistic spin-orbit coupling terms in the heavy metals, and some 'local exchange field' correction to the fields close to nuclei. The problems of the non-local interaction of spins - highly important for alloy theory and for antiferromagnetic instability -required the evolution of computers large enough to produce wave-functions at all wave-vectors for all bands so that the susceptibility at arbitrary wave-vector could be computed. This work has not proved to be very illuminating so far, and much interest again focusses today on heuristic arguments that give qualitative descriptions of band structures, such as canonical d-bands to account for crystal structure. (UK)
Problems of linear electron (polaron) transport theory in semiconductors
Klinger, M I
1979-01-01
Problems of Linear Electron (Polaron) Transport Theory in Semiconductors summarizes and discusses the development of areas in electron transport theory in semiconductors, with emphasis on the fundamental aspects of the theory and the essential physical nature of the transport processes. The book is organized into three parts. Part I focuses on some general topics in the theory of transport phenomena: the general dynamical theory of linear transport in dissipative systems (Kubo formulae) and the phenomenological theory. Part II deals with the theory of polaron transport in a crystalline semicon
A model-dependent approach to the non-relativistic Lamb shift
Diaz-Valdes, J. F.; Bruce, S. A.
2018-02-01
The precise observation of the Lamb shift, between the 2s_{1/2} and 2p_{1/2} levels in hydrogen, was a genuine motivation for the development of modern quantum electrodynamics. According to Dirac theory, the 2s_{1/2} and 2p_{1/2} levels should have equal energies. However, "radiative corrections" due to the interaction between the atomic electron and the vacuum, shift the 2s_{1/2} level higher in energy by around 4.37493× 10^{-6} eV or 2π\\hbar× 1057.85 MHz relative to the 2p_{1/2} level. The measurement of Lamb and Retherford provided the stimulus for renormalization theory which has been so successful in handling troublesome divergences. The Lamb shift is still a central theme in atomic physics. W.E. Lamb was the first to see that this tiny shift, so elusive and hard to measure, would clarify in a fundamental way our thinking about particles and fields. In this article, the Lamb shift for the 2 s energy level in hydrogen is assessed for three different electron models by using the variational principle. It is then verified that this shift arises mostly from the interaction of a bound electron with the zero-point fluctuations of the free electromagnetic field (Welton's interpretation). We briefly comment on the construct validity of the proposed electron models.
Quantum theory of laser radiation scattering by electrons in magnetic fields
International Nuclear Information System (INIS)
Rochlin, H.; Davidovich, L.
1982-01-01
A system consisting of an electron in a static magnetic field, interacting with the quantized electromagnetic field, within the non-relativistic and electric dipole approximations (with a cutoff in momentum space) is considered. The Heisenberg equations of motion are solved exactly and the time evolution of the electric field is determined. The power spectrum of the scattered radiation is calculated, when the electromagnetic field is initially in a coherent state. The results for the line shape of the scattered radiation are shown to be valid for magnetic fields up to 10 12 G. The quantization of the electromagnetic field allows one to consider effects of the natural linewidth and its dependence on the magnetic field. The renormalization of the electron mass is included in these treatment, and the results remain finite when the cutoff goes to infinity. (Author) [pt
Introduction to the theory of low-energy electron diffraction
International Nuclear Information System (INIS)
Fingerland, A.; Tomasek, M.
1975-01-01
An elementary introduction to the basic principles of the theory of low-energy electron diffraction is presented. General scattering theory is used to classify the hitherto known approaches to the problem (optical potential and one-electron approximation; formal scattering theory: Born expansion and multiple scattering; translational symmetry: Ewald construction; classification of LEED theories by means of the T matrix; pseudokinematical theory for crystal with clean surface and with an adsorbed monomolecular layer; dynamical theory; inclusion of inelastic collisions; discussion of a simple example by means of the band-structure approach)
The Search for Beauty-fully Bound Tetraquarks Using Lattice Non-Relativistic QCD
Energy Technology Data Exchange (ETDEWEB)
Hughes, Ciaran [Fermilab; Eichten, Estia [Fermilab; Davies, Christine H. [Glasgow U.
2017-10-09
Motivated by multiple phenomenological considerations, we perform the first search for the existence of a $\\bar{b}\\bar{b}bb$ tetraquark bound state with a mass below the lowest non-interacting bottomonium-pair threshold using the first-principles lattice non-relativistic QCD methodology. We use a full $S$-wave colour/spin basis for the $\\bar{b}\\bar{b}bb$ operators in the three $0^{++}$, $1^{+-}$ and $2^{++}$ channels. We employ four gluon field ensembles at multiple lattice spacing values ranging from $a = 0.06 - 0.12$ fm, all of which include $u$, $d$, $s$ and $c$ quarks in the sea, and one ensemble which has physical light-quark masses. Additionally, we perform novel exploratory work with the objective of highlighting any signal of a near threshold tetraquark, if it existed, by adding an auxiliary potential into the QCD interactions. With our results we find no evidence of a QCD bound tetraquark below the lowest non-interacting thresholds in the channels studied.
Theory of electronic transport through molecular nanostructures
International Nuclear Information System (INIS)
Koentopp, M.B.
2005-05-01
The main issue of this work is to describe electronic transport through single molecule junctions. We implemented the ''standard'' approach to molecular conductance, namely transport calculations in a Landauer-Buettiker framework based on Kohn-Sham orbitals extracted from density functional theory (DFT). Our particular implementation ensures, that apart from approximations inherent in the exchange-correlation functional in DFT no further approximations are made. Comparison of our numerical calculations with available experimental data shows, that, while in some cases qualitative information on transport can be gained, the experimental conductance is two to three orders of magnitude below the theoretical estimate. Changes in bond geometry can not account for this discrepancy. We are led to the conclusion that approximations in the exchange-correlation functional may be the major underlying reason for the discrepancy. To this end, we formulated the condition under which the ''standard'' approach would be exact. Furthermore, we investigated three situations where despite these shortcomings quantitative results can be obtained. Thereby we, for first time, calculated the step positions in the I-V characteristics of a ''diode-type'' molecule quantitatively. (orig.)
Modified Sternglass theory for the emission of secondary electrons by fast-electron impact
International Nuclear Information System (INIS)
Suszcynsky, D.M.; Borovsky, J.E.
1992-01-01
The Sternglass theory [Sternglass, Phys. Rev. 108, 1 (1957)] for fast-ion-induced secondary-electron emission from metals has been modified to predict the secondary-electron yield from metals impacted by energetic (several keV to about 200 keV) electrons. The primary modification of the theory accounts for the contribution of the backscattered electrons to the production of secondary electrons based on a knowledge of the backscattered-electron energy distribution. The modified theory is in reasonable agreement with recent experimental data from gold targets in the 6--30-keV electron energy range
Teaching Valence Shell Electron Pair Repulsion (VSEPR) Theory
Talbot, Christopher; Neo, Choo Tong
2013-01-01
This "Science Note" looks at the way that the shapes of simple molecules can be explained in terms of the number of electron pairs in the valence shell of the central atom. This theory is formally known as valence shell electron pair repulsion (VSEPR) theory. The article explains the preferred shape of chlorine trifluoride (ClF3),…
An introduction to the electron theory of solids
Stringer, John; Hopkins, D W; Finniston, H M
2013-01-01
An Introduction to the Electron Theory of Solids introduces the reader to the electron theory of solids. Topics covered range from the breakdown of classical theory to atomic spectra and the old quantum theory, as well as the uncertainty principle of Heisenberg and the foundations of quantum mechanics. Some problems in wave mechanics and a wave-mechanical treatment of the simple harmonic oscillator and the hydrogen atom are also presented.Comprised of 12 chapters, this book begins with an introduction to Isaac Newton's theory of classical mechanics and how the scientists after him discounted h
The anomalous magnetic moment of the electron
International Nuclear Information System (INIS)
Awobode, A.M.
2002-05-01
The gyromagnetic ratio g of an electron is calculated by taking the non-relativistic limit of a newly proposed extension of the Dirac Hamiltonian coupled to a magnetic field. It is observed that the calculated g is greater than 2; the Dirac theory had predicted that g=2 in sharp contradiction with accurate experimental observations. The additional quantity (g-2)/2≡δ∼(1.6x10 -3 ) is shown here to be due to an extra term which appears in the reduced Hamiltonian, as a consequence of the modification of the rest energy. No divergences are encountered in the calculations described. (author)
Sapir, Nir; Katz, Boaz; Waxman, Eli
2013-09-01
The spectrum of radiation emitted following shock breakout from a star's surface with a power-law density profile ρvpropxn is investigated. Assuming planar geometry, local Compton equilibrium, and bremsstrahlung emission as the dominant photon production mechanism, numerical solutions are obtained for the photon number density and temperature profiles as a function of time for hydrogen-helium envelopes. The temperature solutions are determined by the breakout shock velocity v 0 and the pre-shock breakout density ρ0 and depend weakly on the value of n. Fitting formulae for the peak surface temperature at breakout as a function of v 0 and ρ0 are provided, with {T}_peak\\approx 9.44\\exp {[12.63(v_0/c)^{1/2}]} \\,eV, and the time dependence of the surface temperature is tabulated. The time integrated emitted spectrum is a robust prediction of the model, determined by {T}_peak and v 0 alone and insensitive to details of light travel time or slight deviations from spherical symmetry. Adopting commonly assumed progenitor parameters, breakout luminosities of ≈1045 erg s-1 and ≈1044 erg s-1 in the 0.3-10 keV band are expected for blue supergiant (BSG) and red supergiant (RSG)/He-WR progenitors, respectively ( {T}_peak is well below the band for RSGs, unless their radius is ~1013 cm). >30 detections of SN 1987A-like (BSG) breakouts are expected over the lifetime of ROSAT and XMM-Newton. An absence of such detections would imply either that the typical parameters assumed for BSG progenitors are grossly incorrect or that their envelopes are not hydrostatic. The observed spectrum and duration of XRF 080109/SN 2008D are in tension with a non-relativistic breakout from a stellar surface interpretation.
Theory of coherent transition radiation generated by ellipsoidal electron bunches
Directory of Open Access Journals (Sweden)
W. P. E. M. Op ’t Root
2007-01-01
Full Text Available We present the theory of coherent transition radiation (CTR generated by ellipsoidal electron bunches. We calculate analytical expressions for the electric field spectrum, the power spectrum, and the temporal electric field of CTR, generated by cylindrically symmetric ellipsoidal electron bunches with hard and soft edges. This theory is relevant for diagnostics of ellipsoidal electron bunches. Realization of such bunches would solve the problem of space-charge induced emittance degradation.
Two component theory and electron magnetic moment
Veltman, M.J.G.
1998-01-01
The two-component formulation of quantum electrodynamics is studied. The relation with the usual Dirac formulation is exhibited, and the Feynman rules for the two-component form of the theory are presented in terms of familiar objects. The transformation from the Dirac theory to the two-component
Theory of electron transfer and ionization
International Nuclear Information System (INIS)
Becker, R.L.
1979-01-01
The main effort reported is directed toward charge transfer and ionization in high energy atomic collisions. The research may be divided into classical trajectory calculations, quantum - mechanical collision theory, and phenomenological treatments of quantal interference effects in heavy ion collisions
Electronic-structure theory of plutonium chalcogenides
Czech Academy of Sciences Publication Activity Database
Shick, Alexander; Havela, L.; Gouder, T.; Rebizant, J.
2009-01-01
Roč. 385, č. 1 (2009), 21-24 ISSN 0022-3115 R&D Projects: GA ČR GA202/07/0644; GA MŠk OC 144 Institutional research plan: CEZ:AV0Z10100520 Keywords : electronic structure * electron correlations * photoemission Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.933, year: 2009
Energy Technology Data Exchange (ETDEWEB)
Sapir, Nir; Waxman, Eli [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel); Katz, Boaz [Institute for Advanced Study, Princeton, NJ 08540 (United States)
2013-09-01
The spectrum of radiation emitted following shock breakout from a star's surface with a power-law density profile {rho}{proportional_to}x{sup n} is investigated. Assuming planar geometry, local Compton equilibrium, and bremsstrahlung emission as the dominant photon production mechanism, numerical solutions are obtained for the photon number density and temperature profiles as a function of time for hydrogen-helium envelopes. The temperature solutions are determined by the breakout shock velocity v{sub 0} and the pre-shock breakout density {rho}{sub 0} and depend weakly on the value of n. Fitting formulae for the peak surface temperature at breakout as a function of v{sub 0} and {rho}{sub 0} are provided, with T{sub peak} approx. 9.44 exp [12.63(v{sub 0}/c){sup 1/2}] eV, and the time dependence of the surface temperature is tabulated. The time integrated emitted spectrum is a robust prediction of the model, determined by T{sub peak} and v{sub 0} alone and insensitive to details of light travel time or slight deviations from spherical symmetry. Adopting commonly assumed progenitor parameters, breakout luminosities of Almost-Equal-To 10{sup 45} erg s{sup -1} and Almost-Equal-To 10{sup 44} erg s{sup -1} in the 0.3-10 keV band are expected for blue supergiant (BSG) and red supergiant (RSG)/He-WR progenitors, respectively (T{sub peak} is well below the band for RSGs, unless their radius is {approx}10{sup 13} cm). >30 detections of SN 1987A-like (BSG) breakouts are expected over the lifetime of ROSAT and XMM-Newton. An absence of such detections would imply either that the typical parameters assumed for BSG progenitors are grossly incorrect or that their envelopes are not hydrostatic. The observed spectrum and duration of XRF 080109/SN 2008D are in tension with a non-relativistic breakout from a stellar surface interpretation.
Transport Theory for Kinetic Emission of Secondary Electrons from Solids
DEFF Research Database (Denmark)
Schou, Jørgen
1980-01-01
Kinetic secondary electron emission from a solid target resulting from incidence of keV electrons or keV and MeV ions is treated theoretically on the basis of ionization cascade theory. The energy and angular distribution and the yield of secondary electrons are calculated for a random target...... a spectrum which shows good agreement with experimental data. The electron- and proton-induced yields from aluminum are evaluated on the basis of existing low-energy-electron stopping-power data. The agreement with existing experimental data is good. Also, experimental yields from electrons, protons...
Lessons From Managerial Theories for Improving Virtualness in Electronic Business
Wassenaar, Arjen; Govindaraju, Rajesri; Govindaraju, R.; Moreno Bragado, Elisa; Moreno Bragado, Elisa; von Raesfeld Meijer, Ariane M.; Ribbers, Pieter; Swagerman, D.M.; Sieber, Pascal; Griese, Joachim
1998-01-01
Electronic business and virtual organisations are important research topics in the IS research community today. At the same time these research topics are very appropriate for interdisciplinary research. The panel aims: - presentation of lessons from managerial theories for improving organisational
Electron-positron scattering and gauge theories
International Nuclear Information System (INIS)
Davier, M.
1983-07-01
Recent results from high-energy e + e - colliding facilities are reviewed in the context of gauge theories. First QCD analyses are discussed and difficulties are seen to arise from the interplay between perturbative QCD and non-perturbative fragmentation processes. Many results have been recently obtained on weak electromagnetic interference, strengthening our faith in the standard SU(2) x U(1) theory: however some pieces are still missing and looked for. Finally, vigourous searches are pursued to find clues for physics beyond the SU(3) x SU(2) x U(1) framework: among those supersymmetric particles are being actively hunted in a large variety of situations
Revised theory of Pierce-type electron guns
International Nuclear Information System (INIS)
Sar-El, H.Z.
1982-01-01
Attempts to date to obtain the shape of the beam forming electrodes of various Pierce-type electron guns are briefly discussed with emphasis on the many discrepansis in the results of previous works. A revised theory of Pierce-type electron guns is proposed. The shapes of the beam-forming electrodes for all known configurations of Pierce guns were computed on the basis of the proposed theory. (orig.)
Theory of interrelated electron and proton transfer processes
DEFF Research Database (Denmark)
Kuznetsov, A.M.; Ulstrup, Jens
2003-01-01
A simple theory of elementary act of interrelated reactions of electron and proton transfer is developed. Mechanisms of synchronous and multistage transfer and coherent transitions via a dynamically populated intermediate state are discussed. Formulas for rate constants of adiabatic and nonadiaba......A simple theory of elementary act of interrelated reactions of electron and proton transfer is developed. Mechanisms of synchronous and multistage transfer and coherent transitions via a dynamically populated intermediate state are discussed. Formulas for rate constants of adiabatic...
Quantum theory of the electron liquid
National Research Council Canada - National Science Library
Giuliani, Gabriele; Vignale, Giovanni
2005-01-01
... to the Wigner crystal, from the Luttinger liquid to the quantum Hall liquid, are extensively discussed. Both static and time-dependent density functional theory are presented in detail. Although the emphasis is on the development of the basic physical ideas and on a critical discussion of the most useful approximations, the formal derivation of the r...
Crystal structure from one-electron theory
DEFF Research Database (Denmark)
Skriver, H. L.
1985-01-01
by the theory, the predicted crystal structures are in accord with experiment in all cases except 79Au. In addition, they have investigated the effect of pressure upon the alkali metals (3Li, 11Na, 37Rb, 55Cs) and selected lanthanide metals (57La, 58Ce, 71Lu) and actinide metals (90Th, 91Pa). In these cases...
New mass for the electron, in theory
Quint, W
2003-01-01
There are about a dozen quantities in atomic and nuclear physics that are fundamental to our current understanding of science. One is the speed of light and another is the fine-structure constant, which governs the spectra of atoms. A third is the mass of the lightest atomic particle - the electron. The atomic energy scale is related to our everyday world through the equivalence of the electron's mass and energy, E = mc sup 2. However, while the speed of light, c, is a fixed constant by definition - it has a value of exactly 299 792 458 m s sup 1 - the mass of the electron is not. The mass standard in the atomic world is set by one atom of the element carbon, which is defined to be 12 atomic mass units (about 2x10 sup 2 sup 6 kg). All other masses in the micro-world are related to this mass standard by sophisticated experiments. (U.K.)
Orbital Models and Electronic Structure Theory
DEFF Research Database (Denmark)
Linderberg, Jan
2012-01-01
This tribute to the work by Carl Johan Ballhausen focuses on the emergence of quantitative means for the study of the electronic properties of complexes and molecules. Development, refinement and application of the orbital picture elucidated electric and magnetic features of ranges of molecules w...
Multifrequency Electron Paramagnetic Resonance Theory and Applications
Misra, Sushil K
2011-01-01
Filling the gap for a systematic, authoritative, and up-to-date review of this cutting-edge technique, this book covers both low and high frequency EPR, emphasizing the importance of adopting the multifrequency approach to study paramagnetic systems in full detail by using the EPR method. In so doing, it discusses not only the underlying theory and applications, but also all recent advances -- with a final section devoted to future perspectives.
Quantum tunneling and field electron emission theories
Liang, Shi-Dong
2013-01-01
Quantum tunneling is an essential issue in quantum physics. Especially, the rapid development of nanotechnology in recent years promises a lot of applications in condensed matter physics, surface science and nanodevices, which are growing interests in fundamental issues, computational techniques and potential applications of quantum tunneling. The book involves two relevant topics. One is quantum tunneling theory in condensed matter physics, including the basic concepts and methods, especially for recent developments in mesoscopic physics and computational formulation. The second part is the f
THEORY OF ELECTRON-DEUTERON SCATTERING
Energy Technology Data Exchange (ETDEWEB)
Durand, L. III
1963-06-15
Information on the electromagnetic form factors of the neutron is obtained from the theory of inelastic electrondeuteron scattering. Problems in the analysis of these experiments that are related to the detailed structure of the deuteron and to the strong final state interactions between the emergent nucleons are considered. Problems arising from an ambiguity in the sign of the Dirac or charge form factor are also discussed. (C.E.S.)
International Nuclear Information System (INIS)
Bassi, A.; Donadi, S.
2014-01-01
We study the photon emission rate of a non-relativistic charged particle interacting with an external classical noise through its position. Both the particle and the electromagnetic field are quantized. Under only the dipole approximation, the equations of motion can be solved exactly for a free particle, or a particle bounded by an harmonic potential. The physical quantity we will be interested in is the spectrum of the radiation emitted by the particle, due to the interaction with the noise. We will highlight several properties of the spectrum and clarify some issues appearing in the literature, regarding the exact mathematical formula of a spectrum for a free particle.
Elastic electron-deuteron scattering in vectorlike theories
International Nuclear Information System (INIS)
Gakh, G.I.
1979-01-01
The P odd effects caused by neutral weak currents in the elastic electron-deuteron scattering have been investigated in the vectorlike theories. Cross sections for scattering of both nonpolarized and longitudinally polarized electrons by the deuterons which have both vector and tensor polarizations have been calculated. The general case of the P invariance violation in the elastic electron-deuteron scattering amplitude is considered. The P invariance is violated both in the lepton and the hadron vertices. The vectorlike theory is a particular case when the P invariance is violated only in the hadron vertex
One-Electron Theory of Metals. Cohesive and Structural Properties
DEFF Research Database (Denmark)
Skriver, Hans Lomholt
The work described in the report r.nd the 16 accompanying publications is based upon a one-electron theory obtained within the local approximation to density-functional theory, and deals with the ground state of metals as obtained from selfconsistent electronic-structure calculations performed...... by means of the Linear Muffin-Tin Orbital (LMTO) method. It has been the goal of the work to establish how well this one-electron approach describes physical properties such as the crystal structures of the transition metals, the structural phase transitions in the alkali, alkaline earth, and rare earth...
Theory of Electron-Ion Collisions
Energy Technology Data Exchange (ETDEWEB)
Griffin, Donald C
2009-10-02
Collisions of electrons with atoms and ions play a crucial role in the modeling and diagnostics of fusion plasmas. In the edge and divertor regions of magnetically confined plasmas, data for the collisions of electrons with neutral atoms and low charge-state ions are of particular importance, while in the inner region, data on highly ionized species are needed. Since experimental measurements for these collisional processes remain very limited, data for such processes depend primarily on the results of theoretical calculations. Over the period of the present grant (January 2006 - August 2009), we have made additional improvements in our parallel scattering programs, generated data of direct fusion interest and made these data available on The Controlled Fusion Atomic Data Center Web site at Oak Ridge National Laboratory. In addition, we have employed these data to do collsional-radiative modeling studies in support of a variety of experiments with magnetically confined fusion plasmas.
Electric circuit theory applied electricity and electronics
Yorke, R
1981-01-01
Electric Circuit Theory provides a concise coverage of the framework of electrical engineering. Comprised of six chapters, this book emphasizes the physical process of electrical engineering rather than abstract mathematics. Chapter 1 deals with files, circuits, and parameters, while Chapter 2 covers the natural and forced response of simple circuit. Chapter 3 talks about the sinusoidal steady state, and Chapter 4 discusses the circuit analysis. The fifth chapter tackles frequency response of networks, and the last chapter covers polyphase systems. This book will be of great help to electrical
ORGANIZATIONAL CAPITAL THEORY EXPRESSION OF ELECTRONIC HEALTH
Directory of Open Access Journals (Sweden)
Tomas Vedlūga
2017-03-01
Full Text Available Implementation of e-health is a very difficult and complex process in terms of health policy that requires both organizational ability to meet market requirements and well-managed internal communication, which is carried out through organizational capital and high organizational culture and philosophy. This process requires a change in the organizational processes of health care institutions, ensuring the management and use of health information in order to improve the functioning of health care institutions. Scientists emphasize that health care institutions, with a high organizational capital can effectively promote the development of e-health, by consistently improving the quality of health care services and increasing the confidence and sense of security by enhancing the individual‘s ability to become more involved in the health care system. Nevertheless, in Lithuania, the progress of health care institutions in the field of e-health varies significantly, therefore, different tendencies of e-health care indicators tend to be related to organizational capital. Organizational capital covering the various dimensions of social context analysis, and organizational capital theory is a paradigm that attempts to explain the e-health inequalities at the level of organizations. This paper has evaluated the organizational capital theory expression of the e-health level, to identify and analyze organizational capital assessment indices in the field of e-health and modeled organizational capital assessment scheme.
Linnett Double Quartet Theory, Challenging the Pairing Electrons
Directory of Open Access Journals (Sweden)
Yeganeh Khaniani
2009-01-01
Full Text Available Linnett proposed his theory 45 years after Lewis's supposition. During these years Pauling, Mulliken and Hund made different molecular structure models based on valance bond and molecular orbital theory. Their theories were seemed to fit many experiences but had some inabilities. Linnett's double quartet theory could solved some important problems about stability of radicals, paramagnetism / diamagnetism in molecular systems, electronic structure in transition states and finally challenge of resonance and aromaticity. In this article we review some basic ideas and concepts concerning different models and then we give a detailed discussion of the LDQ and use it in diverse branches of chemistry.
Electronic structure of EuN: Growth, spectroscopy, and theory
DEFF Research Database (Denmark)
Richter, J. H.; Ruck, B.J.; Simpson, M.
2011-01-01
We present a detailed study of the electronic structure of europium nitride (EuN), comparing spectroscopic data to the results of advanced electronic structure calculations. We demonstrate the epitaxial growth of EuN films, and show that in contrast to other rare-earth nitrides successful growth...... and XES) at the nitrogen K edge are compared to several different theoretical models, namely, local spin density functional theory with Hubbard U corrections (LSDA+U), dynamic mean field theory (DMFT) in the Hubbard-I approximation, and quasiparticle self-consistent GW (QSGW) calculations. The DMFT...
Kinetic Theory of Electronic Transport in Random Magnetic Fields
Lucas, Andrew
2018-03-01
We present the theory of quasiparticle transport in perturbatively small inhomogeneous magnetic fields across the ballistic-to-hydrodynamic crossover. In the hydrodynamic limit, the resistivity ρ generically grows proportionally to the rate of momentum-conserving electron-electron collisions at large enough temperatures T . In particular, the resulting flow of electrons provides a simple scenario where viscous effects suppress conductance below the ballistic value. This new mechanism for ρ ∝T2 resistivity in a Fermi liquid may describe low T transport in single-band SrTiO3 .
Lin, M. C.; Chang, P. C.; Lu, P. S.; Verboncoeur, J. P.
2011-10-01
Influence of ion effects on a space charge limited field emission flow has been studied systematically, by employing both analytical and numerical approaches. In our model, the field emission of electrons is described by the Fowler-Nordheim equation. The cathode plasma and surface properties are considered within the framework of an effective work function approximation. Ionization effects at the anode as well as electron space-charge effects are described by Poisson's equation coupled with the energy conservation equation including the relativistic effects. The calculations are carried out self-consistently to yield the steady states of the bipolar flow. The electric field on the cathode surface is found to be saturated due to space charge effects and is determined by the effective work function approximately. In addition, the upstream ion current bas been treated as a tuning parameter. It is found that the field emission currents in the presence of saturated ion currents can be enhanced to be nearly 1.8, 1.5, and 1.4 times of the cases with no upstream ion current in non-relativistic, intermediate, and ultra-relativistic regimes, respectively. The solutions have also been verified using 1D PIC simulations, as implemented in the OOPD1 code developed by PTSG of UC Berkeley. Work supported by the National Science Council, Taiwan, R.O.C. under Grant No. NSC 96-2112-M-030-004-MY3, National Center for Theoretical Sciences, and National Center for High-Performance Computing, Taiwan, ROC which provides the computing resources.
Current functional theory for multi-electron configuration
DEFF Research Database (Denmark)
Bang, Jens N.; Bohr, Henrik
2010-01-01
The density functional theory (DFT) formalism is reformulated into a framework of currents so as to give the energy a parameter dependent behaviour, e.g., time. This “current” method is aimed at describing the transition of electrons from one orbital to another and especially from the ground stat...
Field theory of the spinning electron: I - Internal motions
International Nuclear Information System (INIS)
Salesi, Giovanni; Recami, Erasmo; Universidade Estadual de Campinas, SP
1994-05-01
One of the most satisfactory picture of spinning particles is the Barut-Zanghi (BZ) classical theory for the relativistic electron, that relates the electron spin with the so-called Zitterbewegung (zbw). The BZ theory has been recently studied in the Lagrangian and Hamiltonian symplectic formulations, both in flat and in curved space-time. The BZ motion equations constituted the starting point for two recent works about spin and electron structure, co-authored by us, which adopted the Clifford algebra formalism. In this letter, by employing on the contrary the ordinary tensorial language, we first write down a meaningful (real) equation of motion, describing particle classical paths, quite different from the corresponding (complex) equation of the standard Dirac theory. As a consequence, we succeed in regarding the electron as an extended-type object with a classically intelligible structure (thus overcoming some long-standing, well-known problems). Second, we make explicit the kinematical properties of the 4-velocity field v μ , which also result to be quite different from the ordinary ones, valid for scalar particles. At last, we analyze the inner zbw motions, both time-like and light-like, as functions of the initial conditions (in particular, for the case of classical uniform motions, the z component of spin s is shown to be quantized). In so doing, we make explicit the strict correlation existing between electron polarization and zbw kinematics. (author). 9 refs
Field theory of the spinning electron: I - Internal motions
Energy Technology Data Exchange (ETDEWEB)
Salesi, Giovanni [Universita Statale di Catania (Italy). Dipt. di Fisica; Recami, Erasmo [Universita Statale di Bergamo, Dalmine, BG (Italy). Facolta di Ingegneria]|[Universidade Estadual de Campinas, SP (Brazil). Dept. de Matematica Aplicada
1994-05-01
One of the most satisfactory picture of spinning particles is the Barut-Zanghi (BZ) classical theory for the relativistic electron, that relates the electron spin with the so-called Zitterbewegung (zbw). The BZ theory has been recently studied in the Lagrangian and Hamiltonian symplectic formulations, both in flat and in curved space-time. The BZ motion equations constituted the starting point for two recent works about spin and electron structure, co-authored by us, which adopted the Clifford algebra formalism. In this letter, by employing on the contrary the ordinary tensorial language, we first write down a meaningful (real) equation of motion, describing particle classical paths, quite different from the corresponding (complex) equation of the standard Dirac theory. As a consequence, we succeed in regarding the electron as an extended-type object with a classically intelligible structure (thus overcoming some long-standing, well-known problems). Second, we make explicit the kinematical properties of the 4-velocity field v{sup {mu}}, which also result to be quite different from the ordinary ones, valid for scalar particles. At last, we analyze the inner zbw motions, both time-like and light-like, as functions of the initial conditions (in particular, for the case of classical uniform motions, the z component of spin s is shown to be quantized). In so doing, we make explicit the strict correlation existing between electron polarization and zbw kinematics. (author). 9 refs.
Variational methods in electron-atom scattering theory
Nesbet, Robert K
1980-01-01
The investigation of scattering phenomena is a major theme of modern physics. A scattered particle provides a dynamical probe of the target system. The practical problem of interest here is the scattering of a low energy electron by an N-electron atom. It has been difficult in this area of study to achieve theoretical results that are even qualitatively correct, yet quantitative accuracy is often needed as an adjunct to experiment. The present book describes a quantitative theoretical method, or class of methods, that has been applied effectively to this problem. Quantum mechanical theory relevant to the scattering of an electron by an N-electron atom, which may gain or lose energy in the process, is summarized in Chapter 1. The variational theory itself is presented in Chapter 2, both as currently used and in forms that may facilitate future applications. The theory of multichannel resonance and threshold effects, which provide a rich structure to observed electron-atom scattering data, is presented in Cha...
Two-dimensional theory and simulation of free electron lasers
International Nuclear Information System (INIS)
Kwan, T.J.T.; Cary, J.R.
1981-01-01
Two-dimensional homogeneous theory of free-electron lasers with a wiggler magnetic field of constant wavelength is formulated. It has been found from the theory that waves propagating obliquely with respect to the electron beam are always unstable with appreciable growth rates; therefore, mode competition among the on-axis and off-axis modes is an important consideration in the design of the free-electron laser. Furthermore, electromagnetic waves with group velocities opposite to the direction of electron beam propagation are absolutely unstable if k/sub o/v/sub o/ > ω/sub pe/(1/γ/sup 3/2/ + 1/γ/sup 1/2/). Due to strong nonlinear saturation levels of the low-frequency absolute instability, the dynamics of the electron beam and the generation of the high-frequency electromagnetic radiation can be severely affected. Two-dimensional particle simulations show that the efficiency of generation of the on-axis high-frequency electromagnetic wave decreases significantly due to instability of the off-axis modes. In addition, complete disruption of the electron beam and laser oscillation due to the onset of the absolute instability have been observed in simulations
DC conductivities from non-relativistic scaling geometries with momentum dissipation
Energy Technology Data Exchange (ETDEWEB)
Cremonini, S. [Department of Physics, Lehigh University,16 Memorial Drive East, Bethlehem, PA 18018 (United States); Liu, Hai-Shan [Institute for Advanced Physics & Mathematics, Zhejiang University of Technology,Hangzhou 310023 (China); George P. & Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy,Texas A& M University, College Station, TX 77843 (United States); Lü, H. [Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University,Beijing 100875 (China); Pope, C.N. [George P. & Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy,Texas A& M University, College Station, TX 77843 (United States); Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University,Beijing 100875 (China); DAMTP, Centre for Mathematical Sciences, Cambridge University,Wilberforce Road, Cambridge CB3 OWA (United Kingdom)
2017-04-04
We consider a gravitational theory with two Maxwell fields, a dilatonic scalar and spatially dependent axions. Black brane solutions to this theory are Lifshitz-like and violate hyperscaling. Working with electrically charged solutions, we calculate analytically the holographic DC conductivities when both gauge fields are allowed to fluctuate. We discuss some of the subtleties associated with relating the horizon to the boundary data, focusing on the role of Lifshitz asymptotics and the presence of multiple gauge fields. The axionic scalars lead to momentum dissipation in the dual holographic theory. Finally, we examine the behavior of the DC conductivities as a function of temperature, and comment on the cases in which one can obtain a linear resistivity.
Realistic theory of electronic correlations in nanoscopic systems
Schüler, Malte; Barthel, Stefan; Wehling, Tim; Karolak, Michael; Valli, Angelo; Sangiovanni, Giorgio
2017-07-01
Nanostructures with open shell transition metal or molecular constituents host often strong electronic correlations and are highly sensitive to atomistic material details. This tutorial review discusses method developments and applications of theoretical approaches for the realistic description of the electronic and magnetic properties of nanostructures with correlated electrons. First, the implementation of a flexible interface between density functional theory and a variant of dynamical mean field theory (DMFT) highly suitable for the simulation of complex correlated structures is explained and illustrated. On the DMFT side, this interface is largely based on recent developments of quantum Monte Carlo and exact diagonalization techniques allowing for efficient descriptions of general four fermion Coulomb interactions, reduced symmetries and spin-orbit coupling, which are explained here. With the examples of the Cr (001) surfaces, magnetic adatoms, and molecular systems it is shown how the interplay of Hubbard U and Hund's J determines charge and spin fluctuations and how these interactions drive different sorts of correlation effects in nanosystems. Non-local interactions and correlations present a particular challenge for the theory of low dimensional systems. We present our method developments addressing these two challenges, i.e., advancements of the dynamical vertex approximation and a combination of the constrained random phase approximation with continuum medium theories. We demonstrate how non-local interaction and correlation phenomena are controlled not only by dimensionality but also by coupling to the environment which is typically important for determining the physics of nanosystems.
Search for non-relativistic Magnetic Monopoles with IceCube
DEFF Research Database (Denmark)
Aartsen, M.G.; Abbasi, R.; Ackermann, M.
2014-01-01
Theory (GUT) era shortly after the Big Bang. Depending on the underlying gauge group these monopoles may catalyze the decay of nucleons via the Rubakov–Callan effect with a cross section suggested to be in the range of 10^−27 to 10^−21cm2 . In IceCube, the Cherenkov light from nucleon decays along...
Theory of parametrically amplified electron-phonon superconductivity
Babadi, Mehrtash; Knap, Michael; Martin, Ivar; Refael, Gil; Demler, Eugene
2017-07-01
Ultrafast optical manipulation of ordered phases in strongly correlated materials is a topic of significant theoretical, experimental, and technological interest. Inspired by a recent experiment on light-induced superconductivity in fullerenes [M. Mitrano et al., Nature (London) 530, 461 (2016), 10.1038/nature16522], we develop a comprehensive theory of light-induced superconductivity in driven electron-phonon systems with lattice nonlinearities. In analogy with the operation of parametric amplifiers, we show how the interplay between the external drive and lattice nonlinearities lead to significantly enhanced effective electron-phonon couplings. We provide a detailed and unbiased study of the nonequilibrium dynamics of the driven system using the real-time Green's function technique. To this end, we develop a Floquet generalization of the Migdal-Eliashberg theory and derive a numerically tractable set of quantum Floquet-Boltzmann kinetic equations for the coupled electron-phonon system. We study the role of parametric phonon generation and electronic heating in destroying the transient superconducting state. Finally, we predict the transient formation of electronic Floquet bands in time- and angle-resolved photoemission spectroscopy experiments as a consequence of the proposed mechanism.
Momentum and charge transport in non-relativistic holographic fluids from Hořava gravity
Energy Technology Data Exchange (ETDEWEB)
Davison, Richard A. [Department of Physics, Harvard University, Cambridge, MA 02138 (United States); Grozdanov, Sašo [Instituut-Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, Leiden 2333 CA (Netherlands); Janiszewski, Stefan [Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8W 3P6 (Canada); Kaminski, Matthias [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States)
2016-11-28
We study the linearized transport of transverse momentum and charge in a conjectured field theory dual to a black brane solution of Hořava gravity with Lifshitz exponent z=1. As expected from general hydrodynamic reasoning, we find that both of these quantities are diffusive over distance and time scales larger than the inverse temperature. We compute the diffusion constants and conductivities of transverse momentum and charge, as well the ratio of shear viscosity to entropy density, and find that they differ from their relativistic counterparts. To derive these results, we propose how the holographic dictionary should be modified to deal with the multiple horizons and differing propagation speeds of bulk excitations in Hořava gravity. When possible, as a check on our methods and results, we use the covariant Einstein-Aether formulation of Hořava gravity, along with field redefinitions, to re-derive our results from a relativistic bulk theory.
Transmembrane electron transport and the neutral theory of evolution.
Scherer, S
1984-01-01
Based on the concept of "pairs of basic functional states" the evolution of the first chemiosmotic mechanism of energy conversion is discussed in terms of point mutations, gene duplications and of the neutral theory of evolution. A model for estimating the overall probability of the evolutionary step in question is presented, both for the "selectionist" and "neutralist" position. It is concluded that, concerning the present stage of knowledge, the evolution of transmembrane electron transport is an unsolved problem in evolutionary biology.
Kinetic theory of transport for inhomogeneous electron fluids
Lucas, Andrew; Hartnoll, Sean A.
2018-01-01
The interplay between electronic interactions and disorder is neglected in the conventional Boltzmann theory of transport, yet can play an essential role in determining the resistivity of unconventional metals. When quasiparticles are long lived, one can account for these intertwined effects by solving spatially inhomogeneous Boltzmann equations. Assuming smooth disorder and neglecting umklapp scattering, we solve these inhomogeneous kinetic equations and compute the electrical resistivity across the ballistic-to-hydrodynamic transition. An important consequence of electron-electron interactions is the modification of the momentum-relaxation time; this effect is ignored in the homogeneous theory. We characterize precisely when interactions enhance the momentum scattering rate, and when they decrease it. Our approach unifies existing semiclassical theories of transport, and explains how the resistivity can be proportional to the rate of momentum-conserving collisions without Baber scattering. We compare this result with existing transport mysteries, including the disorder-independent T2 resistivity of many Fermi liquids, and the linear-in-T "Planckian-limited" resistivity of many strange metals.
Theory and Simulation of an Inverse Free Electron Laser Experiment
Guo, S. K.; Bhattacharjee, A.; Fang, J. M.; Marshall, T. C.
1996-11-01
An experimental demonstration of the acceleration of electrons using a high power CO2 laser in an inverse free electron laser (IFEL) is underway at the Brookhaven National Laboratory. This experiment has generated data, which we are attempting to simulate. Included in our studies are such effects as: a low-loss metallic waveguide with a dielectric coating on the walls; multi-mode coupling due to self-consistent interaction between the electrons and the optical wave; space charge (which is significant at lower laser power); energy-spread of the electrons; arbitrary wiggler field profile; and slippage. Two types of wiggler profile have been considered: a linear taper of the period, and a step-taper of the period (the period is ~ 3cm, the field is ~ 1T, and the wiggler length is 47cm). The energy increment of the electrons ( ~ 1-2%) is analyzed in detail as a function of laser power, wiggler parameters, and the initial beam energy (40MeV). For laser power ~ 0.5GW, the predictions of the simulations are in good accord with experimental results. A matter currently under study is the discrepancy between theory and observations for the electron energy distribution observed at the end of the IFEL. This work is supported by the Department of Energy.
Random walk theory applied to electron avalanche formation
Englert, G. W.
1974-01-01
Use of microscopic detail in random walk theory describing the initial formations of a large number of avalanches shows that concomitant electron transport coefficients quickly relax to equilibrium values. This enables the use of random walks having step sizes and probabilities based only on local electric field strengths and densities. A self-consistent avalanche solution which accounts for collective long range Coulomb interactions as well as short range elastic and inelastic collisions between electrons and background atoms is demonstrated for helium. Avalanche growth retardation followed by an abrupt growth augmentation as time proceeds is shown to be associated with the formation of regions of charge density extrema near the avalanche axis and within the axial distance covered by the electron swarm.
Electron transfer dynamics: Zusman equation versus exact theory
International Nuclear Information System (INIS)
Shi Qiang; Chen Liping; Nan Guangjun; Xu Ruixue; Yan Yijing
2009-01-01
The Zusman equation has been widely used to study the effect of solvent dynamics on electron transfer reactions. However, application of this equation is limited by the classical treatment of the nuclear degrees of freedom. In this paper, we revisit the Zusman equation in the framework of the exact hierarchical equations of motion formalism, and show that a high temperature approximation of the hierarchical theory is equivalent to the Zusman equation in describing electron transfer dynamics. Thus the exact hierarchical formalism naturally extends the Zusman equation to include quantum nuclear dynamics at low temperatures. This new finding has also inspired us to rescale the original hierarchical equations and incorporate a filtering algorithm to efficiently propagate the hierarchical equations. Numerical exact results are also presented for the electron transfer reaction dynamics and rate constant calculations.
A multipole acceptability criterion for electronic structure theory
International Nuclear Information System (INIS)
Schwegler, E.; Challacombe, M.; Head-Gordon, M.
1998-01-01
Accurate and computationally inexpensive estimates of multipole expansion errors are crucial to the success of several fast electronic structure methods. In this paper, a new nonempirical multipole acceptability criterion is described that is directly applicable to expansions of high order moments. Several model calculations typical of electronic structure theory are presented to demonstrate its performance. For cases involving small translation distances, accuracies are increased by up to five orders of magnitude over an empirical criterion. The new multipole acceptance criterion is on average within an order of magnitude of the exact expansion error. Use of the multipole acceptance criterion in hierarchical multipole based methods as well as in traditional electronic structure methods is discussed. copyright 1998 American Institute of Physics
Theory of electron attachment to van der Waals clusters
International Nuclear Information System (INIS)
Fabrikant, Ilya I
2005-01-01
A theory of electron collisions with van der Waals clusters is developed which is capable of describing the vibrational Feshbach resonances (VFRs) recently observed in electron attachment to CO 2 clusters. VFRs appear below vibrational excitation thresholds of one molecular unit and their energy decreases with the increase of the cluster size. The selectivity observed in vibrational excitation of individual components of a Fermi dyad is substantially reduced in the attachment spectra. We also calculate elastic electron scattering and vibrational excitation (VE) of one molecular unit in a cluster environment and demonstrate a strong influence of the VFRs on the VE cross sections. Theoretically predicted VFRs are much narrower than observed. We explain the VFR broadening by contribution of several neutral precursors, contribution of different cluster conformations and the dependence of the resonance energy on the position of the molecular unit in the cluster. A model is developed to describe the latter effect quantitatively
The bottom-quark mass from non-relativistic sum rules at NNNLO
Directory of Open Access Journals (Sweden)
M. Beneke
2015-02-01
Full Text Available We determine the mass of the bottom quark from high moments of the bb¯ production cross section in e+e− annihilation, which are dominated by the threshold region. On the theory side next-to-next-to-next-to-leading order (NNNLO calculations both for the resonances and the continuum cross section are used for the first time. We find mbPS(2 GeV=4.532−0.039+0.013 GeV for the potential-subtracted mass and mbMS¯(mbMS¯=4.193−0.035+0.022 GeV for the MS¯ bottom-quark mass.
Abuzaid, N. (Nuha)
2016-01-01
Abstract Hartree-Fock theory, a computational method to solve electronic structure of molecules, is reviewed in this thesis. The emphasis is on spotlighting the physical reasoning behind the assumptions of the Hartree-Fock theory. Also, three post-Hartree-Fock electron correlation methods are introduced, configuration interaction, coupled cluster, and Møller-Plesset theory.
A quantum field theory of the extended electron
Energy Technology Data Exchange (ETDEWEB)
Salesi, Giovanni [Universita Statale di Catania (Italy). Dipt. di Fisica; Recami, Erasmo [Universita Statale di Bergamo, Dalmine, BG (Italy). Facolta di Ingegneria]|[Universidade Estadual de Campinas, SP (Brazil). Dept. de Matematica Aplicada
1993-12-01
In a recent paper, the classical model of Barut and Zanghi (BZ) for the electron spin which interpreted the Zitterbewegung (zbw) motion along helical paths and its quantum version have been investigated by using the language of Clifford algebras. In also doing, a new non-linear Dirac-like equation (NDE) was derived. We want to readdress the whole subject, and complete it, by adopting - for the sake of physical clarity - the ordinary tensorial language. In particular, we re-derive here the NDE for the electron quantum field, show it to be associated with a new conserved probability current, and stress its importance for a quantum field theory of spin 1/2 fermions. Actually, we propose this equation in substitution for the Dirac equation, which comes from the former by averaging over a zbw cycle. We then derive a new equation of motion for the quantum field velocity, which will allow us to regard the electron as an extended object, with a classically intelligible internal structure (thus overcoming some known, long-standing problems). We carefully the solutions of the NDE; with special attention to those implying (at the classical limit) light-like helical motions, since these appear to be the most adequate equations for the electron description, from the kinematical and physical points of view, and do cope with the electron electromagnetic properties (such as Coulomb field and intrinsic magnetic moment). (author). 18 refs.
A quantum field theory of the extended electron
International Nuclear Information System (INIS)
Salesi, Giovanni; Recami, Erasmo; Universidade Estadual de Campinas, SP
1993-12-01
In a recent paper, the classical model of Barut and Zanghi (BZ) for the electron spin which interpreted the Zitterbewegung (zbw) motion along helical paths and its quantum version have been investigated by using the language of Clifford algebras. In also doing, a new non-linear Dirac-like equation (NDE) was derived. We want to readdress the whole subject, and complete it, by adopting - for the sake of physical clarity - the ordinary tensorial language. In particular, we re-derive here the NDE for the electron quantum field, show it to be associated with a new conserved probability current, and stress its importance for a quantum field theory of spin 1/2 fermions. Actually, we propose this equation in substitution for the Dirac equation, which comes from the former by averaging over a zbw cycle. We then derive a new equation of motion for the quantum field velocity, which will allow us to regard the electron as an extended object, with a classically intelligible internal structure (thus overcoming some known, long-standing problems). We carefully the solutions of the NDE; with special attention to those implying (at the classical limit) light-like helical motions, since these appear to be the most adequate equations for the electron description, from the kinematical and physical points of view, and do cope with the electron electromagnetic properties (such as Coulomb field and intrinsic magnetic moment). (author). 18 refs
On the field theory of the extended-type electron
International Nuclear Information System (INIS)
Salesi, G.; Recami, E.
1994-07-01
In a recent paper, the classical theory of Barut and Zhanghi (BZ) for the electron spin [which interpreted the Zitterbewegung (zbw) motion as an internal motion along helical paths] and its ''quantum'' version have been investigated by using the language of Clifford algebras. In so doing, a new non-linear Dirac-like equation (NDE) was derived. We want to readdress the whole subject, and ''complete'' it, by adopting - for the sake of physical clarity - the ordinary tensorial language, within the frame of a first quantization formalism. In particular, we re-derive here the NDE for the electron field, show it to be associated with a new conserved probability current which allows us to work out a quantum probability interpretation of NDE. Actually, we propose this equation in substitution for the Dirac equation, which is obtained from the former by averaging over a zbw cycle. We then derive a new equation of motion for the 4-velocity field which will allow us to regard the electron as an extended object with a classically intelligible internal structure (thus overcoming some known, long-standing problems). We carefully study the solutions of the NDE; with special attention to those implying (at the classical limit) light-like helical motions, since they appear to be the most adequate solutions for the electron description from a kinematical and physical point of view, and to cope with the electromagnetic properties of the electron. (author). 18 refs
Conformal symmetry and non-relativistic second-order fluid dynamics
International Nuclear Information System (INIS)
Chao Jingyi; Schäfer, Thomas
2012-01-01
We study the constraints imposed by conformal symmetry on the equations of fluid dynamics at second order in the gradients of the hydrodynamic variables. At zeroth order, conformal symmetry implies a constraint on the equation of state, E 0 =2/3 P, where E 0 is the energy density and P is the pressure. At first order, conformal symmetry implies that the bulk viscosity must vanish. We show that at second order, conformal invariance requires that two-derivative terms in the stress tensor must be traceless, and that it determines the relaxation of dissipative stresses to the Navier–Stokes form. We verify these results by solving the Boltzmann equation at second order in the gradient expansion. We find that only a subset of the terms allowed by conformal symmetry appear. - Highlights: ► We derive conformal constraints for the stress tensor of a scale invariant fluid. ► We determine the relaxation time in kinetic theory. ► We compute the rate of entropy production in second-order fluid dynamics.
Exact solutions of the dirac equation for an electron in magnetic field with shape invariant method
International Nuclear Information System (INIS)
Setare, M.R.; Hatami, O.
2008-01-01
Based on the shape invariance property we obtain exact solutions of the Virac equation for an electron moving in the presence of a certain varying magnetic Geld, then we also show its non-relativistic limit. (authors)
Transformers and inductors for power electronics theory, design and applications
Hurley, WG
2013-01-01
Based on the fundamentals of electromagnetics, this clear and concise text explains basic and applied principles of transformer and inductor design for power electronic applications. It details both the theory and practice of inductors and transformers employed to filter currents, store electromagnetic energy, provide physical isolation between circuits, and perform stepping up and down of DC and AC voltages. The authors present a broad range of applications from modern power conversion systems. They provide rigorous design guidelines based on a robust methodology for inductor and transform
Quantum theory of the optical and electronic properties of semiconductors
Haug, Hartmut
1990-01-01
The current technological revolution in the development of computing devices has created a demand for a textbook on the quantum theory of the electronic and optical properties of semiconductors and semiconductor devices. This book successfully fulfills this need. Based on lectures given by the authors, it is a comprehensive introduction for researchers or graduate-level students to the subject. Certain sections can also serve as a graduate-level textbook for use in solid state physics courses or for more specialized courses. The final chapters establish a direct link to current research in sem
Introduction to the theory of free electron lasers
International Nuclear Information System (INIS)
Krinsky, S.
1985-01-01
We present an introduction to some fundamental aspects of the theory of free electron lasers. Spontaneous radiation emitted by electrons traversing a wiggler magnet is briefly reviewed, and stimulated emission in the low-gain regime is discussed using Colson's pendulum equations and Madey's theorems. The high-gain regime is treated by an extention of the work of Bonifacio, Pellegrini, and Narducci. We introduce dynamical variables to describe the radiation field, and a Hamiltonian formulation of Maxwell's equations is employed. A canonical transformation to the interaction representation factors out the fast time variation of the radiation field, and the slow time dependence is determined by linearized equations for the appropriate collective variables. As an application of this technique we consider self-amplified spontaneous radiation, and we comment upon the relationship between our approach and the use of coupled Vlasov-Maxwell equations
Electron-Cloud Build-Up: Theory and Data
International Nuclear Information System (INIS)
Furman, M.A.
2010-01-01
We present a broad-brush survey of the phenomenology, history and importance of the electron-cloud effect (ECE). We briefly discuss the simulation techniques used to quantify the electron-cloud (EC) dynamics. Finally, we present in more detail an effective theory to describe the EC density build-up in terms of a few effective parameters. For further details, the reader is encouraged to refer to the proceedings of many prior workshops, either dedicated to EC or with significant EC contents, including the entire 'ECLOUD' series. In addition, the proceedings of the various flavors of Particle Accelerator Conferences contain a large number of EC-related publications. The ICFA Beam Dynamics Newsletter series contains one dedicated issue, and several occasional articles, on EC. An extensive reference database is the LHC website on EC.
Electron-Cloud Build-Up: Theory and Data
Energy Technology Data Exchange (ETDEWEB)
Furman, M. A.
2010-10-08
We present a broad-brush survey of the phenomenology, history and importance of the electron-cloud effect (ECE). We briefly discuss the simulation techniques used to quantify the electron-cloud (EC) dynamics. Finally, we present in more detail an effective theory to describe the EC density build-up in terms of a few effective parameters. For further details, the reader is encouraged to refer to the proceedings of many prior workshops, either dedicated to EC or with significant EC contents, including the entire 'ECLOUD' series. In addition, the proceedings of the various flavors of Particle Accelerator Conferences contain a large number of EC-related publications. The ICFA Beam Dynamics Newsletter series contains one dedicated issue, and several occasional articles, on EC. An extensive reference database is the LHC website on EC.
Strongly correlated electron materials. I. Theory of the quasiparticle structure
Energy Technology Data Exchange (ETDEWEB)
Lopez-Aguilar, F.; Costa-Quintana, J.; Puig-Puig, L. (Departamento de Fisica, Grupo de Electromagnetismo, Universidad Autonoma de Barcelona, Bellaterra, E-08193 Barcelona (Spain))
1993-07-01
In this paper we give a method for analyzing the renormalized electronic structure of the Hubbard systems. The first step is the determination of effective interactions from the random-phase approximation (RPA) and from an extended RPA (ERPA) that introduces vertex effects within the bubble polarization. The second step is the determination of the density of states deduced from the spectral functions. Its analysis leads us to conclude that these systems can exhibit three types of resonances in their electronic structures: the lower-, middle-, and upper-energy resonances. Furthermore, we analyze the conditions for which there is only one type of resonance and the causes that lead to the disappearance of the heavy-fermion state. We finally introduce the RPA and ERPA effective interactions within the strong-coupling theory and we give the conditions for obtaining coupling and superconductivity.
General theory for environmental effects on (vertical) electronic excitation energies.
Schwabe, Tobias
2016-10-21
Almost 70 years ago, the first theoretical model for environmental effects on electronic excitation energies has been derived. Since then, several different interpretations and refined models have been proposed for the perichromic shift of a chromophore due to its surrounding medium. Some of these models are contradictory. Here, the contributing terms are derived within the framework of long-range perturbation theory with the least approximations so far. The derivation is based on a state-specific interpretation of the interaction energies and all terms can be identified with individual properties of either the chromophore or the surroundings, respectively. Further, the much debated contribution due to transition moments coupled to the environment can be verified in the form of a non-resonant excitonic coupling to the dynamic polarizabilities in the environment. These general insights should clarify discussions and interpretations of environmental effects on electronic excitations and should foster the development of new models for the computation of these effects.
Electron scattering from neon via effective range theory
Energy Technology Data Exchange (ETDEWEB)
Fedus, Kamil, E-mail: kamil@fizyka.umk.pl [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun (Poland)
2014-07-01
Elastic cross-sections for electron scattering on neon from 0 energy up to 16 eV are analyzed by an analytical approach to the modified effective range theory (MERT). It is shown that energy and angular variations of elastic differential, integral and momentum transfer cross sections can be accurately parameterized by six MERT coefficients up to the energy threshold for the first Feshbach resonance. MERT parameters are determined empirically by numerical comparison with large collection of available experimental data of elastic total (integral) cross-sections. The present analysis is validated against numerous electron beams and swarm experiments. The comparison of derived MERT parameters with those found for other noble gases, helium, argon and krypton, is done. The derived scattering length (for the s-partial wave) in neon, 0.227a0, agrees well with recent theories; it is small but, differently from Ar and Kr, still positive. Analogue parameters for the p-wave and the d-wave are negative and positive respectively for all the four gases compared. (author)
Semiclassical methods in field theories
International Nuclear Information System (INIS)
Ventura, I.
1978-10-01
A new scheme is proposed for semi-classical quantization in field theory - the expansion about the charge (EAC) - which is developed within the canonical formalism. This method is suitable for quantizing theories that are invariant under global gauge transformations. It is used in the treatment of the non relativistic logarithmic theory that was proposed by Bialynicki-Birula and Mycielski - a theory we can formulate in any number of spatial dimensions. The non linear Schroedinger equation is also quantized by means of the EAC. The classical logarithmic theories - both, the non relativistic and the relativistic one - are studied in detail. It is shown that the Bohr-Sommerfeld quantization rule(BSQR) in field theory is, in many cases, equivalent to charge quantization. This rule is then applied to the massive Thirring Model and the logarithmic theories. The BSQR can be see as a simplified and non local version of the EAC [pt
Gauge theories in particle physics
International Nuclear Information System (INIS)
Aitchison, I.J.R.; Hey, A.J.G.
1982-01-01
The first theory, quantum electrodynamics (QED) is known to give a successful account of electromagnetic interactions. Weak and strong interactions are described by gauge theories which are generalisations of QED. The electro-weak gauge theory of Glashow Salam and Weinberg unites electromagnetic and weak interactions. Quantum chromodynamics (QCD) is the gauge theory of strong interactions. This approach to these theories, designed for the non-specialist, is based on a straightforward generalisation of non-relativistic quantum-mechanical perturbation theory to the relativistic case, leading to an intuitive introduction to Feynman graphs. Spontaneously broken-or 'hidden'-symmetries are given particular attention, with the physics of hidden gauge invariance and the role of the vacuum (essential to the unified theories) being illustrated by an extended but elementary discussion of the non-relativistic example of superconductivity. Throughout, emphasis is placed both on realistic calculations and on physical understanding. (author)
International Nuclear Information System (INIS)
Sitenko, A.
1991-01-01
This book emerged out of graduate lectures given by the author at the University of Kiev and is intended as a graduate text. The fundamentals of non-relativistic quantum scattering theory are covered, including some topics, such as the phase-function formalism, separable potentials, and inverse scattering, which are not always coverded in textbooks on scattering theory. Criticisms of the text are minor, but the reviewer feels an inadequate index is provided and the citing of references in the Russian language is a hindrance in a graduate text
Suzuki, Hiroshi
1967-01-01
Electronic Absorption Spectra and Geometry of Organic Molecules: An Application of Molecular Orbital Theory focuses on electronic absorption spectra of organic compounds and molecules. The book begins with the discussions on molecular spectra, electronic absorption spectra of organic compounds, and practical measures of absorption intensity. The text also focuses on molecular orbital theory and group theory. Molecular state functions; fundamental postulates of quantum theory; representation of symmetry groups; and symmetry operations and symmetry groups are described. The book also dis
Electron avalanche structure determined by random walk theory
Englert, G. W.
1973-01-01
A self-consistent avalanche solution which accounts for collective long range Coulomb interactions as well as short range elastic and inelastic collisions between electrons and background atoms is made possible by a random walk technique. Results show that the electric field patterns in the early formation stages of avalanches in helium are close to those obtained from theory based on constant transport coefficients. Regions of maximum and minimum induced electrostatic potential phi are located on the axis of symmetry and within the volume covered by the electron swarm. As formation time continues, however, the region of minimum phi moves to slightly higher radii and the electric field between the extrema becomes somewhat erratic. In the intermediate formation periods the avalanche growth is slightly retarded by the high concentration of ions in the tail which oppose the external electric field. Eventually the formation of ions and electrons in the localized regions of high field strength more than offset this effect causing a very abrupt increase in avalanche growth.
Kinetic Theory and Fast Wind Observations of the Electron Strahl
Horaites, Konstantinos; Boldyrev, Stanislav; Wilson, Lynn B., III; Viñas, Adolfo F.; Merka, Jan
2018-02-01
We develop a model for the strahl population in the solar wind - a narrow, low-density and high-energy electron beam centred on the magnetic field direction. Our model is based on the solution of the electron drift-kinetic equation at heliospheric distances where the plasma density, temperature and the magnetic field strength decline as power laws of the distance along a magnetic flux tube. Our solution for the strahl depends on a number of parameters that, in the absence of the analytic solution for the full electron velocity distribution function (eVDF), cannot be derived from the theory. We however demonstrate that these parameters can be efficiently found from matching our solution with observations of the eVDF made by the Wind satellite's SWE strahl detector. The model is successful at predicting the angular width (FWHM) of the strahl for the Wind data at 1 au, in particular by predicting how this width scales with particle energy and background density. We find that the strahl distribution is largely determined by the local temperature Knudsen number γ ∼ |T dT/dx|/n, which parametrizes solar wind collisionality. We compute averaged strahl distributions for typical Knudsen numbers observed in the solar wind, and fit our model to these data. The model can be matched quite closely to the eVDFs at 1 au; however, it then overestimates the strahl amplitude at larger heliocentric distances. This indicates that our model may be improved through the inclusion of additional physics, possibly through the introduction of 'anomalous diffusion' of the strahl electrons.
A General Sparse Tensor Framework for Electronic Structure Theory.
Manzer, Samuel; Epifanovsky, Evgeny; Krylov, Anna I; Head-Gordon, Martin
2017-03-14
Linear-scaling algorithms must be developed in order to extend the domain of applicability of electronic structure theory to molecules of any desired size. However, the increasing complexity of modern linear-scaling methods makes code development and maintenance a significant challenge. A major contributor to this difficulty is the lack of robust software abstractions for handling block-sparse tensor operations. We therefore report the development of a highly efficient symbolic block-sparse tensor library in order to provide access to high-level software constructs to treat such problems. Our implementation supports arbitrary multi-dimensional sparsity in all input and output tensors. We avoid cumbersome machine-generated code by implementing all functionality as a high-level symbolic C++ language library and demonstrate that our implementation attains very high performance for linear-scaling sparse tensor contractions.
Structure and Electronic Properties of Cerium Orthophosphate: Theory and Experiment
Energy Technology Data Exchange (ETDEWEB)
Adelstein, Nicole; Mun, B. Simon; Ray, Hannah; Ross Jr, Phillip; Neaton, Jeffrey; De Jonghe, Lutgard
2010-07-27
Structural and electronic properties of cerium orthophosphate (CePO{sub 4}) are calculated using density functional theory (DFT) with the local spin-density approximation (LSDA+U), with and without gradient corrections (GGA-(PBE)+U), and compared to X-ray diffraction and photoemission spectroscopy measurements. The density of states is found to change significantly as the Hubbard parameter U, which is applied to the Ce 4f states, is varied from 0 to 5 eV. The calculated structural properties are in good agreement with experiment and do not change significantly with U. Choosing U = 3 eV for LDSA provides the best agreement between the calculated density of states and the experimental photoemission spectra.
Classical theory of high intensity collisional absorption in a constant magnetic field
Pieruccini, M.; Ferrante, G.; Nuzzo, S.; Zarcone, M.
The problem of gain and loss of kinetic energy by electrons colliding off ions, in the presence of a strong e.m. radiation and of a steady homogeneous magnetic field B, has been investigated within the framework of the classical non relativistic theory. The analysis is first restricted to the elementary process of the electron stimulated direct and inverse bremsstrahlung. The rate of change of the time averaged electron kinetic energy is numerically evaluated for the special cases when the radiation field is either linearly polarized along B, or circularly polarized in a plane perpendicular to B. For the former case, the appropriate Langevin equations are also derived, in order to describe the average motion of test electrons in velocity space.
Molecular Electron Density Theory: A Modern View of Reactivity in Organic Chemistry
Luis R. Domingo
2016-01-01
A new theory for the study of the reactivity in Organic Chemistry, named Molecular Electron Density Theory (MEDT), is proposed herein. MEDT is based on the idea that while the electron density distribution at the ground state is responsible for physical and chemical molecular properties, as proposed by the Density Functional Theory (DFT), the capability for changes in electron density is responsible for molecular reactivity. Within MEDT, the reactivity in Organic Chemistry is studied through ...
Relativistic fluid formulation and theory of intense relativistic electron beams
International Nuclear Information System (INIS)
Siambis, J.G.
1984-01-01
A new general relativistic fluid formulation has been obtained for intense relativistic electron beams (IREB) with arbitrarily high relativistic mass factor γ. This theory is valid for confined IREB equilibria such as those found inside high energy accelerators as well as in the pinched and ion-focused regimes of beam propagation in plasma channels. The new relativistic fluid formulation is based on the covariant relativistic fluid formulation of Newcomb with the parameter lambda identical to 1, in order to allow for realistic confined equilibria. The resulting equilibrium constraints require that the beam has a slow rotational velocity around its direction of propagation and that the off-diagonal thermal stress element, associated with these two directions of motion, be nonzero. The effective betatron oscillation frequency of the fluid elements of the beam is modified by the radial gradient and anisotropies in the thermal stress elements of the beam fluid. The wave equation, for sausage, hose and filamentation excitations on the relativistic fluid beam, is found to be formally identical to that obtained from the Vlasov equation approach, hence phase-mixing damping is a generic and self-consistent correlate of the new relativistic fluid formulation
Theory of longitudinal instability for bunched electron and proton beams
International Nuclear Information System (INIS)
Ruggiero, A.G.
1977-01-01
A discussion is given of an original approach for the treatment of the longitudinal stability of high-intensity proton and electron bunches. The general analysis is divided in three steps. First, a search is made for a stationary bunch distribution which is matched to the external rf forces as well as to the current dependent induced fields. The existence of such distribution is questioned. Second, the stability of the stationary solution is checked by applying a small perturbation and observing whether this is initially damped or not. At this point a stability condition is derived in terms of current, surrounding impedance and bunch size. In the last step one should question what happens to the beam in case the stability condition is not satisfied. The problem here is the determination of the final bunch configuration. The originality of the approach stays in the combination of the three steps. All previous theories either consider only the first step or combine the second and third ones but disregard the first
Theory of thermal conductivity in the disordered electron liquid
International Nuclear Information System (INIS)
Schwiete, G.; Finkel’stein, A. M.
2016-01-01
We study thermal conductivity in the disordered two-dimensional electron liquid in the presence of long-range Coulomb interactions. We describe a microscopic analysis of the problem using the partition function defined on the Keldysh contour as a starting point. We extend the renormalization group (RG) analysis developed for thermal transport in the disordered Fermi liquid and include scattering processes induced by the long-range Coulomb interaction in the sub-temperature energy range. For the thermal conductivity, unlike for the electrical conductivity, these scattering processes yield a logarithmic correction that may compete with the RG corrections. The interest in this correction arises from the fact that it violates the Wiedemann–Franz law. We checked that the sub-temperature correction to the thermal conductivity is not modified either by the inclusion of Fermi liquid interaction amplitudes or as a result of the RG flow. We therefore expect that the answer obtained for this correction is final. We use the theory to describe thermal transport on the metallic side of the metal–insulator transition in Si MOSFETs.
Zheng, Xiao; Yam, ChiYung; Wang, Fan; Chen, GuanHua
2011-08-28
We present the time-dependent holographic electron density theorem (TD-HEDT), which lays the foundation of time-dependent density-functional theory (TDDFT) for open electronic systems. For any finite electronic system, the TD-HEDT formally establishes a one-to-one correspondence between the electron density inside any finite subsystem and the time-dependent external potential. As a result, any electronic property of an open system in principle can be determined uniquely by the electron density function inside the open region. Implications of the TD-HEDT on the practicality of TDDFT are also discussed.
Is quantum theory compatible with special relativity?
Indian Academy of Sciences (India)
2013-03-07
Mar 7, 2013 ... Abstract. How a proposed quantum nonlocal phenomenon could be incompatible with the requirements of special relativity is studied. To show this, the least set of assumptions about the for- malism and the interpretation of non-relativistic quantum theory is considered. Then, without any reference to the ...
Is quantum theory compatible with special relativity?
Indian Academy of Sciences (India)
How a proposed quantum nonlocal phenomenon could be incompatible with the requirements of special relativity is studied. To show this, the least set of assumptions about the formalism and the interpretation of non-relativistic quantum theory is considered. Then, without any reference to the collapse assumption or any ...
Directory of Open Access Journals (Sweden)
S. W. H. Cowley
2006-03-01
Full Text Available Recent spectroscopic observations of Jupiter's "main oval" auroras indicate that the primary auroral electron beam is routinely accelerated to energies of ~100 keV, and sometimes to several hundred keV, thus approaching the relativistic regime. This suggests the need to re-examine the classic non-relativistic theory of auroral electron acceleration by field-aligned electric fields first derived by Knight (1973, and to extend it to cover relativistic situations. In this paper we examine this problem for the case in which the source population is an isotropic Maxwellian, as also assumed by Knight, and derive exact analytic expressions for the field-aligned current density (number flux and kinetic energy flux of the accelerated population, for arbitrary initial electron temperature, acceleration potential, and field strength beneath the acceleration region. We examine the limiting behaviours of these expressions, their regimes of validity, and their implications for auroral acceleration in planetary magnetospheres (and like astrophysical systems. In particular, we show that for relativistic accelerating potentials, the current density increases as the square of the minimum potential, rather than linearly as in the non-relativistic regime, while the kinetic energy flux then increases as the cube of the potential, rather than as the square.
International Nuclear Information System (INIS)
Multiple scale methods are used to treat several ingredients of the theory of atoms in strong electromagnetic fields. First, a focused electromagnetic field is expanded. Second, a classical electron is described giving the ponderomotive potential. Third, the quantum electron is treated in the WKB approximation. Fourth, the one dimensional quantum harmonic oscillator is solved; and last the one dimensional square well, showing the low intensity limit of the theory
Quantitative tests of a steady state theory of solar wind electrons
Feldman, W. C.; Asbridge, J. R.; Bame, S. J.; Gosling, J. T.
1982-01-01
A comparison is made of IMP 6, 7 and 8 electron data with the predictions of a solar wind electron steady state theory in which the control of transport by the macroscopic interplanetary electric and magnetic fields, as well as elastic Coulomb collisions with solar wind protons and thermal electrons, is assumed. While a ratio of forward to backward phase density for field-aligned extrathermal electrons of 6:1 is predicted, electron distribution measurements within the high speed solar wind show this ratio to be typically about an order of magnitude larger. A set of solar wind bulk speed anticorrelations predicted by the theory on the basis of a larger set of assumptions cannot be found in the IMP electron data set, so that improved agreement may require such modifications of the theory's assumptions as the inclusion of inelastic Coulomb and/or wave electron collisions.
International Nuclear Information System (INIS)
Mallet, J.
2012-01-01
This research thesis stands at the crossroad of plasma physics, numerical analysis and applied mathematics. After an introduction presenting the problematic and previous works, the author recalls some basis of classical kinetic models for plasma physics (collisionless kinetic theory and Vlasov equation, collisional kinetic theory with the non-relativistic Maxwell-Fokker-Plansk system) and describes the fundamental properties of the collision operators such as conservation laws, entropy dissipation, and so on. He reports the improvement of a deterministic numerical method to solve the non-relativistic Vlasov-Maxwell system coupled with Fokker-Planck-Landau type operators. The efficiency of each high order scheme is compared. The evolution of the hot spot is studied in the case of thermonuclear reactions in the centre of the pellet in a weakly collisional regime. The author focuses on the simulation of the kinetic electron collisional transport in inertial confinement fusion (ICF) between the laser absorption zone and the ablation front. A new approach is then introduced to reduce the huge computation time obtained with kinetic models. In a last chapter, the kinetic continuous equation in spherical domain is described and a new model is chosen for collisions in order to preserve collision properties
Theory of semiconductor junction devices a textbook for electrical and electronic engineers
Leck, J H
1967-01-01
Theory of Semiconductor Junction Devices: A Textbook for Electrical and Electronic Engineers presents the simplified numerical computation of the fundamental electrical equations, specifically Poisson's and the Hall effect equations. This book provides the fundamental theory relevant for the understanding of semiconductor device theory. Comprised of 10 chapters, this book starts with an overview of the application of band theory to the special case of semiconductors, both intrinsic and extrinsic. This text then describes the electrical properties of conductivity, semiconductors, and Hall effe
Lehtovaara, Lauri; Havu, Ville; Puska, Martti
2009-01-01
We present for static density functional theory and time-dependent density functional theory calculations an all-electron method which employs high-order hierarchical finite-element bases. Our mesh generation scheme, in which structured atomic meshes are merged to an unstructured molecular mesh, allows a highly nonuniform discretization of the space. Thus it is possible to represent the core and valence states using the same discretization scheme, i.e., no pseudopotentials or similar treatmen...
Adiabatic theory of nonlinear electron cyclotron resonance heating
International Nuclear Information System (INIS)
Kotel'nikov, I.A.; Stupakov, G.V.
1989-01-01
Plasma heating at electron frequency by an ordinary wave propagating at right angle to unidirectional magnetic field is treated. Injected microwave power is assumed to be so large that relativistic change of electron gyrofrequency during one flight thorugh the wave beam is much greater than inverse time of flight. The electron motion in the wave field is described using Hamiltonian formalism in adiabatic approximation. It is shown that energy coupling from the wave to electrons is due to a bifurcation of electron trajectory which results in a jumpm of the adiabatic invariant. The probability of bifurcational transition from one trajectory to another is calculated analytically and is used for the estimation of the beam power absorbed in plasma. 6 refs.; 2 figs
Electronic Health Services: An Introduction to Theory and Application
African Journals Online (AJOL)
Information and communication technologies have made dramatic changes in our lives. Healthcare communities also made use of these technologies. Using computerized medical knowledge, electronic patients' information and telecommunications a lot of applications are now established throughout the world.
Nonequilibrium statistical operator in hot-electron transport theory
International Nuclear Information System (INIS)
Xing, D.Y.; Liu, M.
1991-09-01
The Nonequilibrium Statistical Operator method developed by Zubarev is generalized and applied to the study of hot-electron transport in semiconductors. The steady-state balance equations for momentum and energy are derived to the lowest order in the electron-lattice coupling. We show that the derived balance equations are exactly the same as those obtained by Lei and Ting. This equivalence stems from the fact that to the linear order in the electron-lattice coupling, two statistical density matrices have identical effect when they are used to calculate the average value of a dynamical operator. The application to the steady-state and transient hot-electron transport in multivalley semiconductors is also discussed. (author). 28 refs, 1 fig
The Theory of Coherent Radiation by Intense Electron Beams
Buts, Vyacheslav A; Kurilko, V.I
2006-01-01
Spurred by the development of high-current, high-energy relativistic electron beams this books delves into the foundations of a device and geometry independent theoretical treatment of a large collection of interacting and radiating electron bunches. Part I deals with the basics of the radiation emission of a single charged particle, paying particular attention to the effect of radiation reaction and dwelling on the corresponding well-known paradoxes. Part II investigates the collective behaviour of a high-density electron bunch where both discrete and continous beam modelling is explored. Part III treats the application to modern systems while still keeping the treatment as general as possible. This book will be mandatory reading for anyone working on the foundations of modern devices such as free electron lasers, plasma accelerators, synchroton sources and other modern sources of bright, coherent radiation with high spectral density.
Theory of suppression of loss cone instabilities by electron beams
International Nuclear Information System (INIS)
Sinha, A.; Sinha, M.
1981-01-01
A new mechanism for the suppression of Drift Cyclotron Loss Cone instabilities by electron beams injected along the field lines is given. The mechanism explains some of the recent observations. (author)
Nobel Prize 1992: Rudolph A. Marcus: theory of electron transfer reactions in chemical systems
International Nuclear Information System (INIS)
Ulate Segura, Diego Guillermo
2011-01-01
A review of the theory developed by Rudolph A. Marcus is presented, who for his rating to the theory of electron transfer in chemical systems was awarded the Nobel Prize in Chemistry in 1992. Marcus theory has constituted not only a good extension of the use of a spectroscopic principle, but also has provided an energy balance and the application of energy conservation for electron transfer reactions. A better understanding of the reaction coordinate is exposed in terms energetic and establishing the principles that govern the transfer of electrons, protons and some labile small molecular groups as studied at present. Also, the postulates and equations described have established predictive models of reaction time, very useful for industrial environments, biological, metabolic, and others that involve redox processes. Marcus theory itself has also constituted a large contribution to the theory of complex transition [es
The Ghost of Electricity: A History of Electron Theory from 1897 to 1987.
Adams, S. F.
1988-01-01
Discusses the history of electron theory from 1897 to 1987. Includes the works of some physicists, such as Thomson, Lorentz, De Broglie, Bohr, Pauli, Dirac, Feynman, Wheeler, Weinberg, and Salam. (YP)
Introduction of the chronon in the theory of electron and the wave-particle duality
International Nuclear Information System (INIS)
Caldirola, P.
1984-01-01
The author summarizes the more important results obtained in the electron theory based on the chronon and stresses some peculiarities of the wave-particle duality directly connected with the introduction of the chronon. (Auth.)
Electronic structure of disordered transition metals within scattering theory
International Nuclear Information System (INIS)
Yakyibchuk, P.M.; Volkov, O.V.; Vakarchuk, S.O.
2005-01-01
Here we present a new approach to the calculation of density of states of disordered transition metals based on the T-matrix framework presented by Lloyd within generalized Ziman's theory of transport properties and energy structure of disordered metals. This approach makes it possible to avoid such difficulties of familiar calculations as renormalized perturbation theory. We have achieved double hill energy resonance for transition metals at Fe and Co groups caused by hybridization potential. So the results are in good correlation with model presentation of energy structure of these metals conduction band for explaining magnetic and transport properties
Introduction to the theory of X-ray and electronic spectra of free atoms
Karazija, Romas
1996-01-01
Covering both theory and applications, this important work provides a comprehensive introduction to the modern theory of X-ray and electronic spectra of free atoms Romas Karazija discusses methods of angular momenta, irreducible tensorial operators, and coefficients of fractional parentage and their use in determining cross sections and probabilities of elementary processes In addition, Karazija addresses the structure of electronic shells with inner vacancies and many-body effects
International Nuclear Information System (INIS)
Pozdneev, S.A.; Shcheglov, V.A.
1987-01-01
Theory of multiple scattering in the three-body system, which mathematical base is L.D. Fadeev's equations, is applied for calculating the simplest chemical reactions proceeding in electron collision with two-atom molecules. Calculations of cross sections of elastic scattering, excitation, dissociation and dissociative electron attachment to two-atom molecules being in different excited rotational-vibrational states have been performed on the basis of the developed theory
The Theory and Implementation of Electronic Voting Systems
DEFF Research Database (Denmark)
Damgård, Ivan Bjerre; Groth, Jens; Salomonsen, Gorm
2002-01-01
We describe the theory behind a practical voting scheme based on homomorphic encryption. We give an example of an ElGamal-style encryption scheme, which can be used as the underlying cryptosystem. Then, we present efficient honest verifier zero-knowledge proofs that make the messages in the voting...
Theory and measurement of the electron cloud effect
International Nuclear Information System (INIS)
Harkey, K. C.
1999-01-01
Photoelectrons produced through the interaction of synchrotrons radiation and the vacuum chamber walls can be accelerated by a charged particle beam, acquiring sufficient energy to produce secondary electrons (SES) in collisions with the walls. If the secondary-electron yield (SEY) coefficient of the wall material is greater than one, a run-away condition can develop. In addition to the SEY, the degree of amplification depends on the beam intensity and temporal distribution. As the electron cloud builds up along a train of stored bunches, a transverse perturbation of the head bunch can be communicated to trailing bunches in a wakefield-like interaction with the cloud. The electron cloud effect is especially of concern for the high-intensity PEP-II (SLAC) and KEK B-factories and at the Large Hadron Collider (LHC) at CERN. An initiative was undertaken at the Advanced Photon Source (APS) storage ring to characterize the electron cloud in order to provide realistic limits on critical input parameters in the models and improve their predictive capabilities. An intensive research program was undertaken at CERN to address key issues relating to the LHC. After giving an overview, the recent theoretical and experimental results from the APS and the other laboratories will be discussed
Theory of the ionization yield in gases under electron irradiation
International Nuclear Information System (INIS)
Inokuti, M.
1974-01-01
The total number N/sub i/(T) of ionizations that an incident electron of kinetic energy T causes in a pure gas obeys an integral equation known as the Fowler equation. Its solution is shown to closely approximate N/sub i/(T) = (T -- U)/W/sub a/ for T exceeding several multiples of the first ionization energy I, where U and W/sub a/ are constants having the energy dimension. Simple formulas express U and W/sub a/ in terms of various cross sections for electron inelastic collisions with a gas molecule. In particular, U - I represents the average kinetic energy of a subionization electron. (35 refs) (U.S.)
Ab initio electron propagator theory of molecular wires. I. Formalism.
Dahnovsky, Yu; Zakrzewski, V G; Kletsov, A; Ortiz, J V
2005-11-08
Ab initio electron propagator methodology may be applied to the calculation of electrical current through a molecular wire. A new theoretical approach is developed for the calculation of the retarded and advanced Green functions in terms of the electron propagator matrix for the bridge molecule. The calculation of the current requires integration in a complex half plane for a trace that involves terminal and Green's-function matrices. Because the Green's-function matrices have complex poles represented by matrices, a special scheme is developed to express these "matrix poles" in terms of ordinary poles. An expression for the current is derived for a terminal matrix of arbitrary rank. For a single terminal orbital, the analytical expression for the current is given in terms of pole strengths, poles, and terminal matrix elements of the electron propagator. It is shown that Dyson orbitals with high pole strengths and overlaps with terminal orbitals are most responsible for the conduction of electrical current.
Relativistic Many-Body Theory A New Field-Theoretical Approach
Lindgren, Ingvar
2011-01-01
Relativistic Many-Body Theory treats — for the first time — the combination of relativistic atomic many-body theory with quantum-electrodynamics (QED) in a unified manner. This book can be regarded as a continuation of the book by Lindgren and Morrison, Atomic Many-Body Theory (Springer 1986), which deals with the non-relativistic theory of many-electron systems, describing several means of treating the electron correlation to essentially all orders of perturbation theory. The treatment of the present book is based upon quantum-field theory, and demonstrates that when the procedure is carried to all orders of perturbation theory, two-particle systems are fully compatible with the relativistically covariant Bethe-Salpeter equation. This procedure can be applied to arbitrary open-shell systems, in analogy with the standard many-body theory, and it is also applicable to systems with more than two particles. Presently existing theoretical procedures for treating atomic systems are, in several cases, insuffici...
Absorption distances in the dynamical theory of electron diffraction
International Nuclear Information System (INIS)
Kamiya, Yoshihiko; Goto, Toshiaki.
1982-01-01
The contrast effect of the electron microscopic image at crystal defects is characterized by two parameters; extincion distance and absorption distance. Both quantities are orginally defined for the elastic scattering. Since the inelastic scattering contributes to the electron microscopic image, parameters used for the interpretation of the images are not the same as those for the elastic scattering. It is shown that the difference of absorption distance beteen the theoretical estimation and that used for interpretation is due to the contrst effect of the small angle inelastic scattering. (author)
Theory of drift and trapped-electron instabilities
International Nuclear Information System (INIS)
Chen, L.; Cheng, C.Z.; Frieman, E.A.
1978-08-01
This paper deals with the theoretical investigation of low-frequency drift and trapped-particle instabilities in systems with magnetic shear, by analytic and numerical procedures and by computer simulations. In particular, results are presented for calculations which demonstrate: (1) the stability of both collisionless and dissipative drift eigenmodes at long radial wavelengths (k/sub r/rho/sub i/ less than 1) in a sheared slab (one-dimensional) geometry; (2) the presence and structure of drift and trapped-electron eigenmodes in an axisymmetric toroidal (two-dimensional) geometry; and (3) the nonlinear evolution and resultant anomalous transport from trapped-electron instabilities
Hybrid Theory of Electron-Hydrogenic Systems Elastic Scattering
Bhatia, A. K.
2007-01-01
Accurate electron-hydrogen and electron-hydrogenic cross sections are required to interpret fusion experiments, laboratory plasma physics and properties of the solar and astrophysical plasmas. We have developed a method in which the short-range and long-range correlations can be included at the same time in the scattering equations. The phase shifts have rigorous lower bounds and the scattering lengths have rigorous upper bounds. The phase shifts in the resonance region can be used to calculate very accurately the resonance parameters.
Theory of coherent molecule to surface electron injection: An ...
Indian Academy of Sciences (India)
Administrator
erogeneous electron transfer from a molecule to a semiconductor occurs before full vibrational relaxa- tion of the excited molecule is achieved. 5,6. Accor- dingly, theoretical description of the decay of the initial state has been formulated to include vibra- tional coherence in the transfer process. 4. 2. Analytical model.
Density functional theory study of structure, electronic and magnetic ...
Indian Academy of Sciences (India)
Keywords. Rhodium; boron; aluminium; gallium; methanol activation. Abstract. Rhodium clusters are very important finite size materials because of their unique electronic, magneticand catalytic properties. Tuning the physical and chemical properties of rhodium clusters by incorporatingdifferent metal and non-metal atoms ...
Theory of Carbon Nanotube (CNT)-Based Electron Field Emitters
Bocharov, Grigory S.; Eletskii, Alexander V.
2013-01-01
Theoretical problems arising in connection with development and operation of electron field emitters on the basis of carbon nanotubes are reviewed. The physical aspects of electron field emission that underlie the unique emission properties of carbon nanotubes (CNTs) are considered. Physical effects and phenomena affecting the emission characteristics of CNT cathodes are analyzed. Effects given particular attention include: the electric field amplification near a CNT tip with taking into account the shape of the tip, the deviation from the vertical orientation of nanotubes and electrical field-induced alignment of those; electric field screening by neighboring nanotubes; statistical spread of the parameters of the individual CNTs comprising the cathode; the thermal effects resulting in degradation of nanotubes during emission. Simultaneous consideration of the above-listed effects permitted the development of the optimization procedure for CNT array in terms of the maximum reachable emission current density. In accordance with this procedure, the optimum inter-tube distance in the array depends on the region of the external voltage applied. The phenomenon of self-misalignment of nanotubes in an array has been predicted and analyzed in terms of the recent experiments performed. A mechanism of degradation of CNT-based electron field emitters has been analyzed consisting of the bombardment of the emitters by ions formed as a result of electron impact ionization of the residual gas molecules. PMID:28348342
Density functional theory study of structure, electronic and magnetic ...
Indian Academy of Sciences (India)
ABHIJIT DUTTA
2018-01-30
Jan 30, 2018 ... Abstract. Rhodium clusters are very important finite size materials because of their unique electronic, magnetic and catalytic properties. Tuning the physical and chemical properties of rhodium clusters by incorporating different metal and non-metal atoms have found a great research interest in recent years.
Theory of Carbon Nanotube (CNT-Based Electron Field Emitters
Directory of Open Access Journals (Sweden)
Alexander V. Eletskii
2013-07-01
Full Text Available Theoretical problems arising in connection with development and operation of electron field emitters on the basis of carbon nanotubes are reviewed. The physical aspects of electron field emission that underlie the unique emission properties of carbon nanotubes (CNTs are considered. Physical effects and phenomena affecting the emission characteristics of CNT cathodes are analyzed. Effects given particular attention include: the electric field amplification near a CNT tip with taking into account the shape of the tip, the deviation from the vertical orientation of nanotubes and electrical field-induced alignment of those; electric field screening by neighboring nanotubes; statistical spread of the parameters of the individual CNTs comprising the cathode; the thermal effects resulting in degradation of nanotubes during emission. Simultaneous consideration of the above-listed effects permitted the development of the optimization procedure for CNT array in terms of the maximum reachable emission current density. In accordance with this procedure, the optimum inter-tube distance in the array depends on the region of the external voltage applied. The phenomenon of self-misalignment of nanotubes in an array has been predicted and analyzed in terms of the recent experiments performed. A mechanism of degradation of CNT-based electron field emitters has been analyzed consisting of the bombardment of the emitters by ions formed as a result of electron impact ionization of the residual gas molecules.
Kinetic theory analysis of electron attachment cooling in oxygen
International Nuclear Information System (INIS)
Skullerud, H.R.
1983-01-01
The attachment cooling effect observed by Hegerberg and Crompton (1983) has been analysed theoretically and numerically in a Boltzmann equation eigenvalue approach. The effect is highly sensitive to the shape and magnitude of the rotational excitation cross sections. When due account is taken of the rotational excitations associated with the (O 2 - ) negative ion resonances, good agreement between theory and experiment can be obtained with reasonable input cross-section data
Employability Competencies for Entry Level Occupations in Electronics. Part One: Basic Theory.
Werner, Claire
This syllabus, which is the first of a two-volume set describing the basic competencies needed by entry-level workers in the field of electronics, deals with the basic theories of electricity and electronics. Competencies are organized according to the following skills areas: the meaning of electricity, how electricity works, resistors, Ohm's law,…
Noether's theorems applications in mechanics and field theory
Sardanashvily, Gennadi
2016-01-01
The book provides a detailed exposition of the calculus of variations on fibre bundles and graded manifolds. It presents applications in such area's as non-relativistic mechanics, gauge theory, gravitation theory and topological field theory with emphasis on energy and energy-momentum conservation laws. Within this general context the first and second Noether theorems are treated in the very general setting of reducible degenerate graded Lagrangian theory.
Theory of electronic and optical properties of nanostructures
Hewageegana, Prabath S.
"There is plenty of room at the bottom." This bold and prophetic statement from Nobel laureate Richard Feynman back in 1950s at Cal Tech launched the Nano Age and predicted, quite accurately, the explosion in nanoscience and nanotechnology. Now this is a fast developing area in both science and technology. Many think this would bring the greatest technological revolution in the history of mankind. To understand electronic and optical properties of nanostructures, the following problems have been studied. In particular, intensity of mid-infrared light transmitted through a metallic diffraction grating has been theoretically studied. It has been shown that for s-polarized light the enhancement of the transmitted light is much stronger than for p-polarized light. By tuning the parameters of the diffraction grating enhancement can be increased by a few orders of magnitude. The spatial distribution of the transmitted light is highly nonuniform with very sharp peaks, which have the spatial widths about 10 nm. Furthermore, under the ultra fast response in nanostructures, the following two related goals have been proved: (a) the two-photon coherent control allows one to dynamically control electron emission from randomly rough surfaces, which is localized within a few nanometers. (b) the photoelectron emission from metal nanostructures in the strong-field (quasistationary) regime allows coherent control with extremely high contrast, suitable for nanoelectronics applications. To investigate the electron transport properties of two dimensional carbon called graphene, a localization of an electron in a graphene quantum dot with a sharp boundary has been considered. It has been found that if the parameters of the confinement potential satisfy a special condition then the electron can be strongly localized in such quantum dot. Also the energy spectra of an electron in a graphene quantum ring has been analyzed. Furthermore, it has been shown that in a double dot system some
International Nuclear Information System (INIS)
Inokuti, M.; Dillon, M.A.; Kimura, M.
1987-01-01
Ionizing radiations generate in matter a large number of energetic electrons, which in turn collide with molecules in matter, produce ions and excited states, and thereby degrade in energy. The description of the consequences of many collision processes to the electrons and to matter is the goal of the electron degradation theory. They summarize the current understanding of this topic, which is important as a basis of radiation chemistry and biology. In addition, they present an initial report of their new work, namely, a generalization of the Spencer-Fano theory to time-dependent cases
Consistent hydrodynamic theory of chiral electrons in Weyl semimetals
Gorbar, E. V.; Miransky, V. A.; Shovkovy, I. A.; Sukhachov, P. O.
2018-03-01
The complete set of Maxwell's and hydrodynamic equations for the chiral electrons in Weyl semimetals is presented. The formulation of the Euler equation takes into account the explicit breaking of the Galilean invariance by the ion lattice. It is shown that the Chern-Simons (or Bardeen-Zumino) contributions should be added to the electric current and charge densities in Maxwell's equations that provide the information on the separation of Weyl nodes in energy and momentum. On the other hand, these topological contributions do not directly affect the Euler equation and the energy conservation relation for the electron fluid. By making use of the proposed consistent hydrodynamic framework, we show that the Chern-Simons contributions strongly modify the dispersion relations of collective modes in Weyl semimetals. This is reflected, in particular, in the existence of distinctive anomalous Hall waves, which are sustained by the local anomalous Hall currents.
Can Social Cognitive Theories Help Us Understand Nurses' Use of Electronic Health Records?
Strudwick, Gillian; Booth, Richard; Mistry, Kartini
2016-04-01
Electronic health record implementations have accelerated in clinical settings around the world in an effort to improve patient safety and enhance efficiencies related to care delivery. As the largest group of healthcare professionals globally, nurses play an important role in the use of these records and ensuring their benefits are realized. Social cognitive theories such as the Theory of Reasoned Action, Theory of Planned Behaviour, and the Technology Acceptance Model have been developed to explain behavior. Given that variation in nurses' electronic health record utilization may influence the degree to which benefits are realized, the aim of this article is to explore how the use of these social cognitive theories may assist organizations implementing electronic health records to facilitate deeper-level adoption of this type of clinical technology.
Resonances of the confined hydrogen atom and the Lamb-Dicke effect in non-relativistic qed
DEFF Research Database (Denmark)
Faupin, Jeremy
2008-01-01
We study a model describing a system of one dynamical nucleus and one electron confined by their center of mass and interacting with the quantized electromagnetic field. We impose an ultraviolet cutoff and assume that the fine-structure constant is sufficiently small. Using a renormalization group...
Theory of nuclear excitation by electron capture for heavy ions
Energy Technology Data Exchange (ETDEWEB)
Gagyi-Palffy, A.
2006-07-01
The resonant process of nuclear excitation by electron capture (NEEC) in collisions involving highly-charged ions has been investigated theoretically. NEEC is a rare recombination process in which a free electron is captured into a bound shell of an ion with the simultaneous excitation of the nucleus. Total cross sections for NEEC followed by the radiative decay of the excited nucleus are presented for various collision systems. The possibility to observe the NEEC in scattering experiments with trapped or stored ions was discussed focusing on the cases with the largest calculated resonance strength. As the photons emitted in different channels of the electron recombination process are indistinguishable in the total cross section, the interference between NEEC followed by the radiative decay of the nucleus and radiative recombination was investigated. The angular distribution of the emitted photons in the recombination process provides means to discern the two processes. Angular differential cross sections for the emitted photons in the case of E2 nuclear transitions were presented for several heavy elements. (orig.)
Modern electronic structure theory and applications in organic chemistry
Davidson, ER
1997-01-01
This volume focuses on the use of quantum theory to understand and explain experiments in organic chemistry. High level ab initio calculations, when properly performed, are useful in making quantitative distinctions between various possible interpretations of structures, reactions and spectra. Chemical reasoning based on simpler quantum models is, however, essential to enumerating the likely possibilities. The simpler models also often suggest the type of wave function likely to be involved in ground and excited states at various points along reaction paths. This preliminary understanding is n
Molecular Electron Density Theory: A Modern View of Reactivity in Organic Chemistry.
Domingo, Luis R
2016-09-30
A new theory for the study of the reactivity in Organic Chemistry, named Molecular Electron Density Theory (MEDT), is proposed herein. MEDT is based on the idea that while the electron density distribution at the ground state is responsible for physical and chemical molecular properties, as proposed by the Density Functional Theory (DFT), the capability for changes in electron density is responsible for molecular reactivity. Within MEDT, the reactivity in Organic Chemistry is studied through a rigorous quantum chemical analysis of the changes of the electron density as well as the energies associated with these changes along the reaction path in order to understand experimental outcomes. Studies performed using MEDT allow establishing a modern rationalisation and to gain insight into molecular mechanisms and reactivity in Organic Chemistry.
On the proton exchange contribution to electron-hydrogen atom elastic scattering
International Nuclear Information System (INIS)
Mignaco, J.A.; Tort, A.C.
1979-05-01
It is shown that the exchange contribution to the electron-proton potential Born term in elastic electron-hydrogen atom scattering arises as the non relativistic limit from the exchange of a proton between the two participant electrons - calculated from quantum electrodynamics including properly bound states (as solution of Bethe - Salpeter equation). (Author) [pt
A study of runaway electron confinement and theory of neoclassical MHD turbulence
International Nuclear Information System (INIS)
Kwon, Oh Jin
1989-07-01
This thesis consists of two major studies: a study of runaway electron confinement and a theory of neoclassical MHD turbulence. The aim of the former is to study the structure of internal magnetic turbulence in tokamaks, which is thought by many to be responsible for the heat transport. The aim of the latter is to extend existing theories of MHD turbulence in tokamaks into experimentally relevant low-collisionality regimes. This section contains a theory of neoclassical pressure-gradient-driven turbulence and a theory of neoclassical resistivity-gradient-driven turbulence
DEFF Research Database (Denmark)
Dohn, Asmus Ougaard; Møller, Klaus Braagaard; Sauer, Stephan P. A.
2013-01-01
The geometry of tetracyanoplatinate(II) (TCP) has been optimized with density functional theory (DFT) calculations in order to compare different computational strategies. Two approximate scalar relativistic methods, i.e. the scalar zeroth-order regular approximation (ZORA) and non...... is almost quantitatively reproduced in the ZORA and ECP calculations. In addition, the effect of the exchange-correlation functional and one-electron basis set was studied by employing the two generalized gradient approximation (GGA) functionals, BLYP and PBE, as well as their hybrid version B3LYP and PBE0...... in combination with both correlation consistent and Ahlrichs type basis sets. The platinum-carbon bond length (relativistic or non-relativistic) is approximately 1% shorter on using the PBE exchange-correlation functional compared to the BLYP functional but including exact exchange has no significant effect...
Modern quantum chemistry introduction to advanced electronic structure theory
Szabo, Attila
1996-01-01
The aim of this graduate-level textbook is to present and explain, at other than a superficial level, modem ab initio approaches to the calculation of the electronic structure and properties of molecules. The first three chapters contain introductory material culminating in a thorough discussion of the Hartree-Fock approximation.The remaining four chapters describe a variety of more sophisticated approaches, which improve upon this approximation.Among the highlights of the seven chapters are (1) a review of the mathematics (mostly matrix algebra) required for the rest of the book, (2) an intr
Electron spectroscopy of carbon materials: experiment and theory
International Nuclear Information System (INIS)
El-Barbary, A A; Trasobares, S; Ewels, C P; Stephan, O; Okotrub, A V; Bulusheva, L G; Fall, C J; Heggie, M I
2006-01-01
We present a comparative spectroscopic study of carbon as graphite, diamond and C 60 using C1s K-edge electron energy-loss spectroscopy (EELS), X-ray emission spectroscopy, and theoretical modelling. The first principles calculations of these spectra are obtained in the local density approximation using a self-consistent Gaussian basis pseudo-potential method. Calculated spectra show excellent agreement with experiment and are able to discriminate not only between various carbon hybridisations but also local variation in environment. Core-hole effects on the calculated spectra are also investigated. For the first time, the EEL spectrum of carbyne is calculated
Electron spectroscopy of carbon materials: experiment and theory
Energy Technology Data Exchange (ETDEWEB)
El-Barbary, A A [University of Sussex, School of Life Sciences, Falmer, Brighton, BN1 9QJ (United Kingdom); University of Ain-Shams, Faculty of Education, Department of Physics, Cairo (Egypt); Trasobares, S [Laboratoire de physique des Solides Batiment 510, Universite Paris Sud 91405, Orsay (France); Departamento de Ciencia de los Materiales Ingenieria Metalurgica Quimica Inorganica, Universidad de Cadiz, Apdo 40 Puerto Real, 11510-Cadiz (Spain); Ewels, C P [University of Sussex, School of Life Sciences, Falmer, Brighton, BN1 9QJ (United Kingdom); Stephan, O [Laboratoire de physique des Solides Batiment 510, Universite Paris Sud 91405, Orsay (France); Okotrub, A V [Nikolaev Institute of Inorganic Chemistry SB RAS, pr. Ak. Lavrentieva 3 (Russian Federation); Bulusheva, L G [Nikolaev Institute of Inorganic Chemistry SB RAS, pr. Ak. Lavrentieva 3 (Russian Federation); Fall, C J [ELCA Informatique SA, Avenue de la Harpe 22-24, CH-1000 Lausanne 13 (Switzerland); Heggie, M I [University of Sussex, School of Life Sciences, Falmer, Brighton, BN1 9QJ (United Kingdom)
2006-02-22
We present a comparative spectroscopic study of carbon as graphite, diamond and C{sub 60} using C1s K-edge electron energy-loss spectroscopy (EELS), X-ray emission spectroscopy, and theoretical modelling. The first principles calculations of these spectra are obtained in the local density approximation using a self-consistent Gaussian basis pseudo-potential method. Calculated spectra show excellent agreement with experiment and are able to discriminate not only between various carbon hybridisations but also local variation in environment. Core-hole effects on the calculated spectra are also investigated. For the first time, the EEL spectrum of carbyne is calculated.
Electron-electron attractive interaction in Maxwell-Chern-Simons QED3 at zero temperature
International Nuclear Information System (INIS)
Belich, H.; Ferreira Junior, M.M.; Helayel-Neto, J.A.; Ferreira Junior, M.M.
2001-04-01
One discusses the issue of low-energy electron-electron bound states in the Maxwell-Chern-Simons model coupled to QED 3 with spontaneous breaking of a local U(1)-symmetry. The scattering potential, in the non-relativistic limit, steaming from the electron-electron Moeller scattering, mediated by the Maxwell-Chern-Simons-Proca gauge field and the Higgs scalar, might be attractive by fine-tuning properly the physical parameters of the model. (author)
Quantum theory of the optical and electronic properties of semiconductors
Haug, Hartmut
2009-01-01
This invaluable textbook presents the basic elements needed to understand and research into semiconductor physics. It deals with elementary excitations in bulk and low-dimensional semiconductors, including quantum wells, quantum wires and quantum dots. The basic principles underlying optical nonlinearities are developed, including excitonic and many-body plasma effects. Fundamentals of optical bistability, semiconductor lasers, femtosecond excitation, the optical Stark effect, the semiconductor photon echo, magneto-optic effects, as well as bulk and quantum-confined Franz-Keldysh effects, are covered. The material is presented in sufficient detail for graduate students and researchers with a general background in quantum mechanics.This fifth edition includes an additional chapter on 'Quantum Optical Effects' where the theory of quantum optical effects in semiconductors is detailed. Besides deriving the 'semiconductor luminescence equations' and the expression for the stationary luminescence spectrum, the resu...
The impact of electronic media violence: scientific theory and research.
Huesmann, L Rowell
2007-12-01
Since the early 1960s, research evidence has been accumulating that suggests that exposure to violence in television, movies, video games, cell phones, and on the Internet increases the risk of violent behavior on the viewer's part, just as growing up in an environment filled with real violence increases the risk of them behaving violently. In the current review this research evidence is critically assessed and the psychological theory that explains why exposure to violence has detrimental effects for both the short and long-term is elaborated. Finally the size of the "media violence effect" is compared with some other well-known threats to society to estimate how important a threat it should be considered.
The Impact of Electronic Media Violence: Scientific Theory and Research
Huesmann, L. Rowell
2009-01-01
Since the early 1960s research evidence has been accumulating that suggests that exposure to violence in television, movies, video games, cell phones, and on the internet increases the risk of violent behavior on the viewer’s part just as growing up in an environment filled with real violence increases the risk of them behaving violently. In the current review this research evidence is critically assessed, and the psychological theory that explains why exposure to violence has detrimental effects for both the short run and long run is elaborated. Finally, the size of the “media violence effect” is compared with some other well known threats to society to estimate how important a threat it should be considered. PMID:18047947
Analytical theory of the Bunemann instability for electron runaway
International Nuclear Information System (INIS)
Kaeppeler, H.J.
1988-10-01
Generally, analytical expressions for the growth rate of the Bunemann instability are given for small ratios of beam density n b to plasma density n p and are derived for zero applied electric field. In the case of this instability caused by runaway electrons, e.g. in the dense plasma focus or z-pinch, there exists an appreciable induced electric field strength and the assumption of n b /n p << 1 can no longer be made. In this report, a simplified dispersion relation including an applied, time-variable electric field is derived and an approximate analytical expression for the temporal growth rate is given. The magnetic field is assumed to be zero. (orig.)
Electron-deuteron scattering in a relativistic theory of hadrons
International Nuclear Information System (INIS)
Phillips, D.
1998-11-01
The author reviews a three-dimensional formalism that provides a systematic way to include relativistic effects including relativistic kinematics, the effects of negative-energy states, and the boosts of the two-body system in calculations of two-body bound-states. He then explains how to construct a conserved current within this relativistic three-dimensional approach. This general theoretical framework is specifically applied to electron-deuteron scattering both in impulse approximation and when the ρπγ meson-exchange current is included. The experimentally-measured quantities A, B, and T 20 are calculated over the kinematic range that is probed in Jefferson Lab experiments. The role of both negative-energy states and meson retardation appears to be small in the region of interest
Quantum field theory treatment of magnetic effects on a system of free electrons
Verzegnassi, C.; Germano, R.; Kurian, P.
2018-03-01
The effects of a magnetic field on the energy and on the spin of free electrons are computed in the theoretical framework of quantum field theory. In the case of a static moderate field and with relatively slow electrons, the derived formulae are particularly simple. A comparison with the approaches of classical physics and of quantum mechanics shows essential differences and important analogies. The relevance to the magnetic effects of the initial polarization components of the electron states and the possible existence of special values of these quantities are discussed in the final conclusions, which might be useful to explain recent experiments on quasi-free electrons in chiral systems in biology.
Time-dependent density functional theory for many-electron systems interacting with cavity photons.
Tokatly, I V
2013-06-07
Time-dependent (current) density functional theory for many-electron systems strongly coupled to quantized electromagnetic modes of a microcavity is proposed. It is shown that the electron-photon wave function is a unique functional of the electronic (current) density and the expectation values of photonic coordinates. The Kohn-Sham system is constructed, which allows us to calculate the above basic variables by solving self-consistent equations for noninteracting particles. We suggest possible approximations for the exchange-correlation potentials and discuss implications of this approach for the theory of open quantum systems. In particular we show that it naturally leads to time-dependent density functional theory for systems coupled to the Caldeira-Leggett bath.
Renormalization theory of beam-beam interaction in electron-positron colliders
International Nuclear Information System (INIS)
Chin, Y.H.
1989-07-01
This note is devoted to explaining the essence of the renormalization theory of beam-beam interaction for carrying out analytical calculations of equilibrium particle distributions in electron-positron colliding beam storage rings. Some new numerical examples are presented such as for betatron tune dependence of the rms beam size. The theory shows reasonably good agreements with the results of computer simulations. 5 refs., 6 figs
ELECTRON CYCLOTRON CURRENT DRIVE IN DIII-D: EXPERIMENT AND THEORY
International Nuclear Information System (INIS)
PRATER, R; PETTY, CC; LUCE, TC; HARVEY, RW; CHOI, M; LAHAYE, RJ; LIN-LIU, Y-R; LOHR, J; MURAKAMI, M; WADE, MR; WONG, K-L
2003-01-01
A271 ELECTRON CYCLOTRON CURRENT DRIVE IN DIII-D: EXPERIMENT AND THEORY. Experiments on the DIII-D tokamak in which the measured off-axis electron cyclotron current drive has been compared systematically to theory over a broad range of parameters have shown that the Fokker-Planck code CQL3D provides an excellent model of the relevant current drive physics. This physics understanding has been critical in optimizing the application of ECCD to high performance discharges, supporting such applications as suppression of neoclassical tearing modes and control and sustainment of the current profile
Directory of Open Access Journals (Sweden)
Cleanthes Anthony Nicolaides
2018-03-01
Full Text Available A variety of processes originating from the interaction of atomic or molecular N-electron states with strong and/or hypershort radiation pulses can be understood quantitatively only by first determining with good accuracy the solutions of the many-electron time-dependent Schrödinger equation (METDSE that describe the corresponding physics. The METDSE is solvable nonperturbatively via the state-specific expansion approach (SSEA. SSEA solutions have been used, or can be used, for quantitative explanation and numerically reliable predictions of quantities that have been measured or are measurable in modern laser-driven experiments that can track, with hypershort (attosecond time resolution, the effects of electron rearrangements in atoms and molecules. The calculations take into account in a transparent way the interplay between the phenomena and the electronic structures of the physically significant states in discrete and multichannel continuous spectra, including multiply- and inner-hole–excited resonance states. The discussion focuses on novel topics of time-resolved many-electron physics and includes a comparison of our predictions to recent quantitative measurements of attosecond-resolved generation of the profile of the doubly excited resonance state of helium during photoionization and of the relative time delay in photoemission of the (2s,2p electrons of neon.
Relativistic light-shift theory of few-electron systems: Heliumlike highly charged ions
Postavaru, O.; Scafes, A. C.
2017-09-01
The light-shift theory of many-electron systems in a laser field is described using the projection operators technique. In heavy ions, the electrons are tightly bound by the Coulomb potential of the nucleus, which prohibits ionization even by strong lasers. However, interaction with the monofrequent laser field leads to dynamic shifts of the electronic energy levels, and the process is treated by second-order time-dependent perturbation theory. In order to treat heliumlike systems, one decomposes the corresponding matrix elements into hydrogenlike matrix elements using the independent particle model. We are applying a fully relativistic description of the electronic states by means of the Dirac equation. Our formalism goes beyond the Stark long-wavelength dipole approximation and takes into account nondipole effects of retardation and interaction with the magnetic field components of the laser beam.
Directory of Open Access Journals (Sweden)
Hwang Sungmin
2017-01-01
Full Text Available We present our calculation of the non-relativistic corrections to the heavy quark-antiquark potential up to leading and next-to-leading order (NLO via the effective string theory (EST. Full systematics of effective field theory (EFT are discussed in order for including the NLO contribution that arises in the EST. We also show how the number of dimensionful parameters arising from the EST are reduced by the constraints between the Wilson coeffcients from non-relativistic EFTs for QCD.
Perturbation theory of strongly correlated electrons with and without slave boson technique
International Nuclear Information System (INIS)
Nguyen Van Hieu; Ha Vinh Tan; Nguyen Toan Thang; Nguyen Ai Viet.
1988-10-01
The Green functions of the electrons in the two-band Hubbard model with the strong on-site Coulomb repulsion were calculated by means of the perturbation theory with respect to the hopping term of the Hamiltonian. It was shown that in the slave boson technique we obtain the expressions different from the results of the calculations involving directly electron operators without using slave bosons. The physical meaning of this discrepancy was discussed. (author)
Many-body theory of electron-positron interaction in metallic lithium
Energy Technology Data Exchange (ETDEWEB)
Stachowiak, H. [Polska Akademia Nauk, Wroclaw (Poland). Inst. Niskich Temperatur i Badan Strukturalnych
1997-10-01
Development of hypernetted-chain approach to the electronic structure of simple metals offers the possibility to perform many-body calculations of the electron-positron interaction in these materials. A theory of this interaction is proposed and applied to lithium. It leads to nonlinear three-dimensions integro-differential equation for the enhancement amplitude. This equation is solved for two cases in which it reduces to one dimension. (author). 4 refs, 3 figs.
Recent investigations on electronic capture in atomic collisions
International Nuclear Information System (INIS)
Rivarola, R.D.
1988-01-01
In this work, electron capture processes in ion-atom collisions at various impact energy ranges are dicussed: i) intermediate non-relativistic energy; ii) high energy; iii) high relativistic energy. Much attention is given to the development and use of distorted wave models. (A.C.A.S.) [pt
International Nuclear Information System (INIS)
Lemons, Don S.
2012-01-01
We develop a Markov process theory of charged particle scattering from stationary, transverse, magnetic waves. We examine approximations that lead to quasilinear theory, in particular the resonant diffusion approximation. We find that, when appropriate, the resonant diffusion approximation simplifies the result of the weak turbulence approximation without significant further restricting the regime of applicability. We also explore a theory generated by expanding drift and diffusion rates in terms of a presumed small correlation time. This small correlation time expansion leads to results valid for relatively small pitch angle and large wave energy density - a regime that may govern pitch angle scattering of high-energy electrons into the geomagnetic loss cone.
Fractional Electron Loss in Approximate DFT and Hartree-Fock Theory.
Peach, Michael J G; Teale, Andrew M; Helgaker, Trygve; Tozer, David J
2015-11-10
Plots of electronic energy vs electron number, determined using approximate density functional theory (DFT) and Hartree-Fock theory, are typically piecewise convex and piecewise concave, respectively. The curves also commonly exhibit a minimum and maximum, respectively, in the neutral → anion segment, which lead to positive DFT anion HOMO energies and positive Hartree-Fock neutral LUMO energies. These minima/maxima are a consequence of using basis sets that are local to the system, preventing fractional electron loss. Ground-state curves are presented that illustrate the idealized behavior that would occur if the basis set were to be modified to enable fractional electron loss without changing the description in the vicinity of the system. The key feature is that the energy cannot increase when the electron number increases, so the slope cannot be anywhere positive, meaning frontier orbital energies cannot be positive. For the convex (DFT) case, the idealized curve is flat beyond a critical electron number such that any additional fraction of an electron added to the system is unbound. The anion HOMO energy is zero. For the concave (Hartree-Fock) case, the idealized curve is flat up to some critical electron number, beyond which it curves down to the anion energy. A minimum fraction of an electron is required before any binding occurs, but beyond that, the full fraction abruptly binds. The neutral LUMO energy is zero. Approximate DFT and Hartree-Fock results are presented for the F → F(-) segment, and results approaching the idealized behavior are recovered for highly diffuse basis sets. It is noted that if a DFT calculation using a highly diffuse basis set yields a negative LUMO energy then a fraction of an electron must bind and the electron affinity must be positive, irrespective of whether an electron binds experimentally. This is illustrated by calculations on Ne → Ne(-).
Chern-Simons field theory of two-dimensional electrons in the lowest Landau level
International Nuclear Information System (INIS)
Zhang, L.
1996-01-01
We propose a fermion Chern-Simons field theory describing two-dimensional electrons in the lowest Landau level. This theory is constructed with a complete set of states, and the lowest-Landau-level constraint is enforced through a δ functional described by an auxiliary field λ. Unlike the field theory constructed directly with the states in the lowest Landau level, this theory allows one, utilizing the physical picture of open-quote open-quote composite fermion,close-quote close-quote to study the fractional quantum Hall states by mapping them onto certain integer quantum Hall states; but, unlike its application in the unconstrained theory, such a mapping is sensible only when interactions between electrons are present. An open-quote open-quote effective mass,close-quote close-quote which characterizes the scale of low energy excitations in the fractional quantum Hall systems, emerges naturally from our theory. We study a Gaussian effective theory and interpret physically the dressed stationary point equation for λ as an equation for the open-quote open-quote mass renormalization close-quote close-quote of composite fermions. copyright 1996 The American Physical Society
Energy Technology Data Exchange (ETDEWEB)
Peng, Bo; Kowalski, Karol
2017-03-01
In this letter, we introduce the reverse Cuthill-McKee (RCM) algorithm, which is often used for the bandwidth reduction of sparse tensors, to transform the two-electron integral tensors to their block diagonal forms. By further applying the pivoted Cholesky decomposition (CD) on each of the diagonal blocks, we are able to represent the high-dimensional two-electron integral tensors in terms of permutation matrices and low-rank Cholesky vectors. This representation facilitates the low-rank factorization of the high-dimensional tensor contractions that are usually encountered in post-Hartree-Fock calculations. In this letter, we discuss the second-order Møller-Plesset (MP2) method and linear coupled- cluster model with doubles (L-CCD) as two simple examples to demonstrate the efficiency of the RCM-CD technique in representing two-electron integrals in a compact form.
Trapped Electron Instability of Electron Plasma Waves: Vlasov simulations and theory
Berger, Richard; Chapman, Thomas; Brunner, Stephan
2013-10-01
The growth of sidebands of a large-amplitude electron plasma wave is studied with Vlasov simulations for a range of amplitudes (. 001 vph = +/-ωbe , where vph =ω0 /k0 and ωbe is the bounce frequency of a deeply trapped electron. In 2D simulations, we find that the instability persists and co-exists with the filamentation instability. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the Laboratory Research and Development Program at LLNL under project tracking code 12-ERD.
Directory of Open Access Journals (Sweden)
Mahdi Afshar
2013-11-01
Full Text Available We have demonstrated electronic structure and magnetic properties of Cu3, Ag3 and Au3 trimers using a full potential local orbital method in the framework of relativistic density functional theory. We have also shown that the non-relativistic generalized gradient approximation for the exchange-correlation energy functional gives reliable magnetic properties in coinage metal trimers compared to experiment. In addition we have indicated that the spin-orbit coupling changes the structure and magnetic properties of gold trimer while the structure and magnetic properties of copper and silver trimers are marginally affected. A significant orbital moment of 0.21μB was found for most stable geometry of the gold trimer whereas orbital magnetism is almost quenched in the copper and silver trimers.
DEFF Research Database (Denmark)
Gavnholt, Jeppe; Rubio, Angel; Olsen, Thomas
2009-01-01
Using time-evolution time-dependent density functional theory (TDDFT) within the adiabatic local-density approximation, we study the interactions between single electrons and molecular resonances at surfaces. Our system is a nitrogen molecule adsorbed on a ruthenium surface. The surface is modeled...... at two levels of approximation, first as a simple external potential and later as a 20-atom cluster. We perform a number of calculations on an electron hitting the adsorbed molecule from inside the surface and establish a picture, where the resonance is being probed by the hot electron. This enables us...
Tian, Justin; Wang, Xu; Eberly, J. H.
2017-05-01
The lack of analytical solutions for the exit momentum in the laser-driven tunneling theory is a well-recognized problem in strong field physics. Theoretical studies of electron momentum distributions in the neighborhood of the tunneling exit depend heavily on ad hoc assumptions. In this Letter, we apply a new numerical method to study the exiting electron's longitudinal momentum distribution under intense short-pulse laser excitation. We present the first realizations of the dynamic behavior of an electron near the so-called tunneling exit region without adopting a tunneling approximation.
Electron impact excitation of the D states of Mg, Ca and Sr atoms ...
Indian Academy of Sciences (India)
electron impact energies of 20 and 40 eV. We compare our results obtained from both the non-relativistic and relativistic methods with each other. Good agreement is found on comparison and the importance of relativistic effects is also explored. Keywords. Electron; excitation; atoms; complete experiment. PACS Nos 34.80.
Khazanov, George V.; Sibeck, David G.
2013-01-01
The interaction of electrons with coherent chorus waves in the random phase approximation can be described as quasi-linear diffusion for waves with amplitudes below some limit. The limit is calculated for relativistic and non-relativistic electrons. For stronger waves, the friction force should be taken into account.
Density functional theory for strongly-interacting electrons: Perspectives for Physics and Chemistry
Gori Giorgi, P.; Seidl, M.
2010-01-01
Improving the accuracy and thus broadening the applicability of electronic density functional theory (DFT) is crucial to many research areas, from material science, to theoretical chemistry, biophysics and biochemistry. In the last three years, the mathematical structure of the strong-interaction
Linear-response theory of Coulomb drag in coupled electron systems
DEFF Research Database (Denmark)
Flensberg, Karsten; Hu, Ben Yu-Kuang; Jauho, Antti-Pekka
1995-01-01
We report a fully microscopic theory for the transconductivity, or, equivalently, the momentum transfer rate, of Coulomb coupled electron systems. We use the Kubo linear-response formalism and our main formal result expresses the transconductivity in terms of two fluctuation diagrams, which...
DEFF Research Database (Denmark)
Silva-Junior, Mario R.; Schreiber, Marko; Sauer, Stephan P. A.
2008-01-01
Time-dependent density functional theory (TD-DFT) and DFT-based multireference configuration interaction (DFT/MRCI) calculations are reported for a recently proposed benchmark set of 28 medium-sized organic molecules. Vertical excitation energies, oscillator strengths, and excited-state dipole...... moments are computed using the same geometries (MP2/6-31G*) and basis set (TZVP) as in our previous ab initio benchmark study on electronically excited states. The results from TD-DFT (with the functionals BP86, B3LYP, and BHLYP) and from DFT/MRCI are compared against the previous high-level ab initio...
International Workshop on Electronic Density Functional Theory : Recent Progress and New Directions
Vignale, Giovanni; Das, Mukunda
1998-01-01
This book is an outcome of the International Workshop on Electronic Density Functional Theory, held at Griffith University in Brisbane, Australia, in July 1996. Density functional theory, standing as it does at the boundary between the disciplines of physics, chemistry, and materials science, is a great mixer. Invited experts from North America, Europe, and Australia mingled with students from several disciplines, rapidly taking up the informal style for which Australia is famous. A list of participants is given at the end of the book. Density functional theory (DFT) is a subtle approach to the very difficult problem of predicting the behavior of many interacting particles. A major application is the study of many-electron systems. This was the workshop theme, embracing inter alia computational chemistry and condensed matter physics. DFT circumvents the more conceptually straightforward (but more computationally intensive) approach in which one solves the many-body Schrodinger equation. It relies instead on r...
International Nuclear Information System (INIS)
Astapenko, V.A.; Bureeva, L.A.; Lisitsa, V.S.
2000-01-01
Classical and quantum theories of polarization bremsstrahlung in a statistical (Thomas-Fermi) potential of complex atoms and ions are developed. The basic assumptions of the theories correspond to the approximations employed earlier in classical and quantum calculations of ordinary bremsstrahlung in a static potential. This makes it possible to study on a unified basis the contribution of both channels in the radiation taking account of their interference. The classical model makes it possible to obtain simple universal formulas for the spectral characteristics of the radiation. The theory is applied to electrons with moderate energies, which are characteristic for plasma applications, specifically, radiation from electrons on the argon-like ion KII at frequencies close to its ionization potential. The computational results show the importance of taking account of the polarization channel of the radiation for plasma with heavy ions
International Nuclear Information System (INIS)
Perez, R.; Sheinin, S.S.
1984-01-01
The electron microscope is one of the most important tools used in the study of the structure of materials. In order to interpret the experimental micrographs obtained from this instrument a theoretical model which relates image contrast to specimen structure must be constructed. In order to obtain useful information experimental micrographs must normally be compared to the results of theoretical calculations based on this model. The theory involved in these calculations is normally the dynamical theory of electron diffraction. In employing this theory many approximations must be made. The study of the validity of these approximations has become increasingly important in recent years because of the growing interest in obtaining higher resolution information from experimental micrographs. These studies involve in the first instance the development of more general forms of the theory in which the approximation being studied is not made. Assessments of diffraction conditions under which conventional forms of the theory might be expected to break down can then be made and experiomental verification of these results carried out. The work presented in this paper analyses the ranges of validity of four different approximations: the symmetrical Laue diffraction conditions, the column approximation, a many-beam form of the dynamical theory for crystals containing twin boundaries and an assessment of many-beam effects in HCP perfect crystals. (author)
Rayka, Milad; Goli, Mohammad; Shahbazian, Shant
2018-02-07
An effective set of Hartree-Fock (HF) equations are derived for electrons of muonic systems, i.e., molecules containing a positively charged muon, conceiving the muon as a quantum oscillator, which are completely equivalent to the usual two-component HF equations used to derive stationary states of the muonic molecules. In these effective equations, a non-Coulombic potential is added to the orthodox coulomb and exchange potential energy terms, which describes the interaction of the muon and the electrons effectively and is optimized during the self-consistent field cycles. While in the two-component HF equations a muon is treated as a quantum particle, in the effective HF equations it is absorbed into the effective potential and practically transformed into an effective potential field experienced by electrons. The explicit form of the effective potential depends on the nature of muon's vibrations and is derivable from the basis set used to expand the muonic spatial orbital. The resulting effective Hartree-Fock equations are implemented computationally and used successfully, as a proof of concept, in a series of muonic molecules containing all atoms from the second and third rows of the Periodic Table. To solve the algebraic version of the equations muon-specific Gaussian basis sets are designed for both muon and surrounding electrons and it is demonstrated that the optimized exponents are quite distinct from those derived for the hydrogen isotopes. The developed effective HF theory is quite general and in principle can be used for any muonic system while it is the starting point for a general effective electronic structure theory that incorporates various types of quantum correlations into the muonic systems beyond the HF equations.
Multi-scale modelling and numerical simulation of electronic kinetic transport
International Nuclear Information System (INIS)
Duclous, R.
2009-11-01
This research thesis which is at the interface between numerical analysis, plasma physics and applied mathematics, deals with the kinetic modelling and numerical simulations of the electron energy transport and deposition in laser-produced plasmas, having in view the processes of fuel assembly to temperature and density conditions necessary to ignite fusion reactions. After a brief review of the processes at play in the collisional kinetic theory of plasmas, with a focus on basic models and methods to implement, couple and validate them, the author focuses on the collective aspect related to the free-streaming electron transport equation in the non-relativistic limit as well as in the relativistic regime. He discusses the numerical development and analysis of the scheme for the Vlasov-Maxwell system, and the selection of a validation procedure and numerical tests. Then, he investigates more specific aspects of the collective transport: the multi-specie transport, submitted to phase-space discontinuities. Dealing with the multi-scale physics of electron transport with collision source terms, he validates the accuracy of a fast Monte Carlo multi-grid solver for the Fokker-Planck-Landau electron-electron collision operator. He reports realistic simulations for the kinetic electron transport in the frame of the shock ignition scheme, the development and validation of a reduced electron transport angular model. He finally explores the relative importance of the processes involving electron-electron collisions at high energy by means a multi-scale reduced model with relativistic Boltzmann terms
Density functional theory description of electronic properties of wurtzite zinc oxide
Franklin, L.; Ekuma, C. E.; Zhao, G. L.; Bagayoko, D.
2013-05-01
We report calculated, electronic properties of wurtzite zinc oxide (w-ZnO). We solved self-consistently the two inherently coupled equations of density functional theory (DFT), following the Bagayoko, Zhao, and Williams (BZW) method as enhanced by the work of Ekuma and Franklin (BZW-EF). We employed a local density approximation (LDA) potential and the linear combination of atomic orbitals (LCAO). Most of the calculated, electronic properties of w-ZnO are in excellent agreement with experiment, including our zero temperature band gap of 3.39 eV and the electron effective mass. The doubly self-consistent approach utilized in this work points to the ability of theory to predict accurately key properties of semiconductors and hence to inform and to guide the design and fabrication of semiconductor-based devices.
Electron-electron attractive interaction in Maxwell-Chern-Simons QED{sub 3} at zero temperature
Energy Technology Data Exchange (ETDEWEB)
Belich, H.; Ferreira Junior, M.M.; Helayel-Neto, J.A. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). E-mail: belich@cbpf.br; manojr@cbpf.br; helayel@gft.ucp.br; Ferreira Junior, M.M. [Universidade Catolica de Petropolis, RJ (Brazil). Grupo de Fisica Teorica. E-mail: delcima@gft.ucp.br
2001-04-01
One discusses the issue of low-energy electron-electron bound states in the Maxwell-Chern-Simons model coupled to QED{sub 3} with spontaneous breaking of a local U(1)-symmetry. The scattering potential, in the non-relativistic limit, steaming from the electron-electron Moeller scattering, mediated by the Maxwell-Chern-Simons-Proca gauge field and the Higgs scalar, might be attractive by fine-tuning properly the physical parameters of the model. (author)
Understanding valence-shell electron-pair repulsion (VSEPR) theory using origami molecular models
Endah Saraswati, Teguh; Saputro, Sulistyo; Ramli, Murni; Praseptiangga, Danar; Khasanah, Nurul; Marwati, Sri
2017-01-01
Valence-shell electron-pair repulsion (VSEPR) theory is conventionally used to predict molecular geometry. However, it is difficult to explore the full implications of this theory by simply drawing chemical structures. Here, we introduce origami modelling as a more accessible approach for exploration of the VSEPR theory. Our technique is simple, readily accessible and inexpensive compared with other sophisticated methods such as computer simulation or commercial three-dimensional modelling kits. This method can be implemented in chemistry education at both the high school and university levels. We discuss the example of a simple molecular structure prediction for ammonia (NH3). Using the origami model, both molecular shape and the scientific justification can be visualized easily. This ‘hands-on’ approach to building molecules will help promote understanding of VSEPR theory.
Cho, Yeongsu; Berkelbach, Timothy C.
2018-01-01
We present an electrostatic theory of band-gap renormalization in atomically thin semiconductors that captures the strong sensitivity to the surrounding dielectric environment. In particular, our theory aims to correct known band gaps, such as that of the three-dimensional bulk crystal. Combining our quasiparticle band gaps with an effective-mass theory of excitons yields environmentally sensitive optical gaps as would be observed in absorption or photoluminescence. For an isolated monolayer of MoS2, the presented theory is in good agreement with ab initio results based on the G W approximation and the Bethe-Salpeter equation. We find that changes in the electronic band gap are almost exactly offset by changes in the exciton binding energy such that the energy of the first optical transition is nearly independent of the electrostatic environment, rationalizing experimental observations.
Understanding valence-shell electron-pair repulsion (VSEPR) theory using origami molecular models
International Nuclear Information System (INIS)
Saraswati, Teguh Endah; Saputro, Sulistyo; Ramli, Murni; Praseptiangga, Danar; Khasanah, Nurul; Marwati, Sri
2017-01-01
Valence-shell electron-pair repulsion (VSEPR) theory is conventionally used to predict molecular geometry. However, it is difficult to explore the full implications of this theory by simply drawing chemical structures. Here, we introduce origami modelling as a more accessible approach for exploration of the VSEPR theory. Our technique is simple, readily accessible and inexpensive compared with other sophisticated methods such as computer simulation or commercial three-dimensional modelling kits. This method can be implemented in chemistry education at both the high school and university levels. We discuss the example of a simple molecular structure prediction for ammonia (NH_3). Using the origami model, both molecular shape and the scientific justification can be visualized easily. This ‘hands-on’ approach to building molecules will help promote understanding of VSEPR theory. (paper)
Delange, Pascal; Backes, Steffen; van Roekeghem, Ambroise; Pourovskii, Leonid; Jiang, Hong; Biermann, Silke
2018-04-01
The most intriguing properties of emergent materials are typically consequences of highly correlated quantum states of their electronic degrees of freedom. Describing those materials from first principles remains a challenge for modern condensed matter theory. Here, we review, apply and discuss novel approaches to spectral properties of correlated electron materials, assessing current day predictive capabilities of electronic structure calculations. In particular, we focus on the recent Screened Exchange Dynamical Mean-Field Theory scheme and its relation to generalized Kohn-Sham Theory. These concepts are illustrated on the transition metal pnictide BaCo2As2 and elemental zinc and cadmium.
Tiwari, Vivek; Peters, William K; Jonas, David M
2017-10-21
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.
DEFF Research Database (Denmark)
Hofener, S.; Ahlrichs, R.; Knecht, S.
2012-01-01
errors larger than 0.1 eV for Ga2, Ge2, and Sb2. Only relativistic treatments are presented for the 6p-block cases Tl2 to At2. Sufficient agreement with experimental data is found only for Pb2 and Bi2, the deviation of the computed and experimental D0 values for Po2 is again larger than 0.1 e...
Non-relativistic quantum mechanics
Puri, Ravinder R
2017-01-01
This book develops and simplifies the concept of quantum mechanics based on the postulates of quantum mechanics. The text discusses the technique of disentangling the exponential of a sum of operators, closed under the operation of commutation, as the product of exponentials to simplify calculations of harmonic oscillator and angular momentum. Based on its singularity structure, the Schrödinger equation for various continuous potentials is solved in terms of the hypergeometric or the confluent hypergeometric functions. The forms of the potentials for which the one-dimensional Schrödinger equation is exactly solvable are derived in detail. The problem of identifying the states of two-level systems which have no classical analogy is addressed by going beyond Bell-like inequalities and separability. The measures of quantumness of mutual information in two two-level systems is also covered in detail. Offers a new approach to learning quantum mechanics based on the history of quantum mechanics and its postu...
Super-Galilei invariant field theories in 2+1 dimensions
International Nuclear Information System (INIS)
Bergman, O.; Thorn, C.B.
1995-01-01
The authors extend the Galilei group of space-time transformations by gradation, construct interacting field-theoretic representations of this algebra, and show that non-relativistic Super-Chern-Simons theory is a special case. They also study the generalization to matrix valued fields, which are relevant to the formulation of superstring theory as a 1/N c expansion of a field theory. The authors find that in the matrix case, the field theory is much more restricted by the supersymmetry
International Nuclear Information System (INIS)
Solontsov, A.
2015-01-01
The paper critically overviews the recent developments of the theory of spatially dispersive spin fluctuations (SF) in itinerant electron magnetism with particular emphasis on spin-fluctuation coupling or spin anharmonicity. It is argued that the conventional self-consistent renormalized (SCR) theory of spin fluctuations is usually used aside of the range of its applicability actually defined by the constraint of weak spin anharmonicity based on the random phase approximation (RPA) arguments. An essential step in understanding SF in itinerant magnets beyond RPA-like arguments was made recently within the soft-mode theory of SF accounting for strong spin anharmonicity caused by zero-point SF. In the present paper we generalize it to apply for a wider range of temperatures and regimes of SF and show it to lead to qualitatively new results caused by zero-point effects. - Highlights: • We review the spin-fluctuation theory of itinerant electron magnets with account of zero-point effects. • We generalize the existing theory to account for different regimes of spin fluctuations. • We show that zero-point spin fluctuations play a crucial role in both low- and high-temperature properties of metallic magnets. • We argue that a new scheme of calculation of ground state properties of magnets is needed including zero-point effects
Gulans, Andris; Kontur, Stefan; Meisenbichler, Christian; Nabok, Dmitrii; Pavone, Pasquale; Rigamonti, Santiago; Sagmeister, Stephan; Werner, Ute; Draxl, Claudia
2014-09-10
Linearized augmented planewave methods are known as the most precise numerical schemes for solving the Kohn-Sham equations of density-functional theory (DFT). In this review, we describe how this method is realized in the all-electron full-potential computer package, exciting. We emphasize the variety of different related basis sets, subsumed as (linearized) augmented planewave plus local orbital methods, discussing their pros and cons and we show that extremely high accuracy (microhartrees) can be achieved if the basis is chosen carefully. As the name of the code suggests, exciting is not restricted to ground-state calculations, but has a major focus on excited-state properties. It includes time-dependent DFT in the linear-response regime with various static and dynamical exchange-correlation kernels. These are preferably used to compute optical and electron-loss spectra for metals, molecules and semiconductors with weak electron-hole interactions. exciting makes use of many-body perturbation theory for charged and neutral excitations. To obtain the quasi-particle band structure, the GW approach is implemented in the single-shot approximation, known as G(0)W(0). Optical absorption spectra for valence and core excitations are handled by the solution of the Bethe-Salpeter equation, which allows for the description of strongly bound excitons. Besides these aspects concerning methodology, we demonstrate the broad range of possible applications by prototypical examples, comprising elastic properties, phonons, thermal-expansion coefficients, dielectric tensors and loss functions, magneto-optical Kerr effect, core-level spectra and more.
Quantum Theory of Conducting Matter Newtonian Equations of Motion for a Bloch Electron
Fujita, Shigeji
2007-01-01
Quantum Theory of Conducting Matter: Newtonian Equations of Motion for a Bloch Electron targets scientists, researchers and graduate-level students focused on experimentation in the fields of physics, chemistry, electrical engineering, and material sciences. It is important that the reader have an understanding of dynamics, quantum mechanics, thermodynamics, statistical mechanics, electromagnetism and solid-state physics. Many worked-out problems are included in the book to aid the reader's comprehension of the subject. The Bloch electron (wave packet) moves by following the Newtonian equation of motion. Under an applied magnetic field B the electron circulates around the field B counterclockwise or clockwise depending on the curvature of the Fermi surface. The signs of the Hall coefficient and the Seebeck coefficient are known to give the sign of the major carrier charge. For alkali metals, both are negative, indicating that the carriers are "electrons." These features arise from the Fermi surface difference...
An application of random field theory to analysis of electron trapping sites in disordered media
International Nuclear Information System (INIS)
Hilczer, M.; Bartczak, W.M.
1993-01-01
The potential energy surface in a disordered medium is considered a random field and described using the concepts of the mathematical theory of random fields. The preexisting traps for excess electrons are identified with certain regions of excursion (extreme regions) of the potential field. The theory provides an analytical method of statistical analysis of these regions. Parameters of the cavity-averaged potential field, which are provided by computer simulation of a given medium, serve as input data for the analysis. The statistics of preexisting traps are obtained for liquid methanol as a numerical example of the random field method. 26 refs., 6 figs
Fluctuations in an electron-positron plasma: linear theory and implications for turbulence
Energy Technology Data Exchange (ETDEWEB)
Gary, S Peter [Los Alamos National Laboratory; Karimabadi, Homa [UCSD
2009-01-01
Linear kinetic theory of electromagnetic fluctuations in a homogeneous, magnetized, collisionless electron-positron plasma predicts two lightly damped modes propagate at relatively long wavelengths: an Alfven-like mode with dispersion {omega}{sub r} = k{sub {parallel}}{bar {nu}}{sub A} and a magnetosonic-like mode with dispersion {omega}{sub r} {approx_equal} k{bar {nu}}{sub A} if {beta}{sub e} << 1. Here {bar {nu}}{sub A} is the Alfven speed in an electron-positron plasma and {parallel} refers to the direction relative to the background magnetic field B{sub 0}. Alfven-like fluctuations are incompressible, but the magnetosoniclike fluctuations become compressible at propagation oblique to B{sub 0}. The onset of cyclotron damping of both modes moves to smaller k{sub {parallel}}c/{omega}{sub e} as {beta}{sub {parallel}e} increases. Using the linear dispersion properties of these modes, scaling relations are derived which predict that turbulence of both modes should be relatively anisotropic, with fluctuating magnetic energy preferentially cascading in directions relatively perpendicular to B{sub 0}. But two-regime turbulence with a distinct breakpoint in wavenumber space observed in the solar wind should not be present in electron-positron plasmas because of the absence of whistler-like dispersion. Linear theory properties of the cyclotron and mirror instabilities driven by either electron or positron temperature anisotropies are generally analogous to the corresponding instabilities in electron-proton plasmas.
Fluctuations in electron-positron plasmas: Linear theory and implications for turbulence
International Nuclear Information System (INIS)
Gary, S. Peter; Karimabadi, Homa
2009-01-01
Linear kinetic theory of electromagnetic fluctuations in a homogeneous, magnetized, collisionless electron-positron plasma predicts two lightly damped modes propagate at relatively long wavelengths: an Alfven-like mode with dispersion ω r =k || v-tilde A and a magnetosonic-like mode with dispersion ω r ≅kv-tilde A if β e A is the Alfven speed in an electron-positron plasma and || refers to the direction relative to the background magnetic field B o . Both modes have phase speeds ω r /k which monotonically decrease with increasing wavenumber. The Alfven-like fluctuations are almost incompressible, but the magnetosonic-like fluctuations become strongly compressible at short wavelengths and propagation sufficiently oblique to B o . Using the linear dispersion properties of these modes, scaling relations are derived which predict that turbulence of both modes should be relatively anisotropic, with fluctuating magnetic energy preferentially cascading in directions perpendicular to B o . Turbulent spectra in the solar wind show two distinct power-law regimes separated by a distinct breakpoint in observed frequency; this characteristic should not be present in electron-positron turbulence because of the absence of whistler-like dispersion. Linear theory properties of the cyclotron and mirror instabilities driven by either electron or positron temperature anisotropies are generally analogous to those of the corresponding instabilities in electron-proton plasmas.
Hydrated electron yields in liquid and supercritical water—a theory
International Nuclear Information System (INIS)
Schiller, Robert; Horváth, Ákos
2012-01-01
Our theory, outlined earlier [Schiller, R., 1990. Ion-electron pairs in condensed polar media treated as H-like atoms. J. Chem. Phys. 92, 5527–5532.], is based on the idea that the electron and its geminate positive ion form a hydrogen-like atom, which can be ionized at the expense of the energy fluctuations in the medium. Temperature, T, static relative permittivity, ε s , and constant-volume molar specific heat, C v m , play here the decisive role; the combination Tε s 2 √(C v m ), is the variable by which the yield can be predicted. The calculations agree with the recent experimental results on the temperature dependent yields of hydrated electrons by Kratz et al. [Kratz, S., Torres-Alcan, J., Urbanek, J., Lindner, J., Vöhringer, P., 2010. Geminate recombination of hydrated electrons in liquid-to-supercritical water studied by ultrafast time-resolved spectroscopy. Phys. Chem. Chem. Phys. 12, 12169–12176.] reasonably well. - Highlights: ► A theory of hydrated electron yield as a function of temperature is presented. ► Geminate recombination is regarded to be the decisive process. ► Its probability is described in terms of quantum mechanics and statistical mechanics. ► Probability depends on temperature, dielectric constant and specific heat. ► Calculations reproduce the yields observed in liquid and supercritical water.
Quantum chemistry the development of ab initio methods in molecular electronic structure theory
Schaefer III, Henry F
2004-01-01
This guide is guaranteed to prove of keen interest to the broad spectrum of experimental chemists who use electronic structure theory to assist in the interpretation of their laboratory findings. A list of 150 landmark papers in ab initio molecular electronic structure methods, it features the first page of each paper (which usually encompasses the abstract and introduction). Its primary focus is methodology, rather than the examination of particular chemical problems, and the selected papers either present new and important methods or illustrate the effectiveness of existing methods in predi
Non-Markovian theory for the waiting time distributions of single electron transfers.
Welack, Sven; Yan, YiJing
2009-09-21
We derive a non-Markovian theory for waiting time distributions of consecutive single electron transfer events. The presented microscopic Pauli rate equation formalism couples the open electrodes to the many-body system, allowing to take finite bias and temperature into consideration. Numerical results reveal transient oscillations of distinct system frequencies due to memory in the waiting time distributions. Memory effects can be approximated by an expansion in non-Markovian corrections. This method is employed to calculate memory landscapes displaying preservation of memory over multiple consecutive electron transfers.
Spiegelberg, Jakob; Rusz, Ján
2015-12-01
In the framework of the slice transition operator technique, a general multislice theory for electron scattering in crystals is developed. To achieve this generalization, we combine the approaches for inelastic scattering derived by Yoshioka [J. Phys. Soc. Jpn. 12, 6 (1957)] and backscattering based on the formalism of Chen and Van Dyck [Ultramicroscopy 70, 29-44 (1997)]. A computational realization of the obtained equations is suggested. The proposed computational scheme is tested on elastic backscattering of electrons, where we consider single backscattering in analogy to the computational scheme proposed by Chen and Van Dyck. Copyright © 2015 Elsevier B.V. All rights reserved.
Resonant R-matrix theory of inelastic processes in collisions of electrons with HF molecules
International Nuclear Information System (INIS)
Fabrikant, I.I.; Kalin, S.A.; Kazansky, A.K.
1992-01-01
The resonant R-matrix theory is applied to the calculation of vibrational excitation and dissociative attachment cross sections in collisions of electrons with HF molecules. The parameters of our model were chosen by fitting our eigenphase sums for e-HF scattering to the results of ab initio R-matrix calculations by previous authors. Another set of parameters was chosen to get a better agreement with experimental results on vibrational excitation. Dissociative attachment cross sections calculated with these parameters are in good agreement with experimental results. We also calculated cross sections for vibrational excitation from excited states and angular distribution of the scattered electrons. (author)
Asymptotic theory of dissipative trapped electron mode overlapping many rational surfaces
International Nuclear Information System (INIS)
Rogister, A.; Hasselberg, G.
1978-01-01
The two dimensional eigenvalue equation describing the dissipative trapped electron mode is solved exactly in the limit of the mode overlapping many rational surfaces using the Pogutse model for the magnetic field and the pitch angle collision operator. The trapped electron contribution to the growth rate decreases, with respect to the standard theory, by a factor of order Δ/chi sub(T) << 1 where chi sub(T) is the position of the turning point and Δ the distance between rational surfaces
Bohr's Electron was Problematic for Einstein: String Theory Solved the Problem
Webb, William
2013-04-01
Neils Bohr's 1913 model of the hydrogen electron was problematic for Albert Einstein. Bohr's electron rotates with positive kinetic energies +K but has addition negative potential energies - 2K. The total net energy is thus always negative with value - K. Einstein's special relativity requires energies to be positive. There's a Bohr negative energy conflict with Einstein's positive energy requirement. The two men debated the problem. Both would have preferred a different electron model having only positive energies. Bohr and Einstein couldn't find such a model. But Murray Gell-Mann did! In the 1960's, Gell-Mann introduced his loop-shaped string-like electron. Now, analysis with string theory shows that the hydrogen electron is a loop of string-like material with a length equal to the circumference of the circular orbit it occupies. It rotates like a lariat around its centered proton. This loop-shape has no negative potential energies: only positive +K relativistic kinetic energies. Waves induced on loop-shaped electrons propagate their energy at a speed matching the tangential speed of rotation. With matching wave speed and only positive kinetic energies, this loop-shaped electron model is uniquely suited to be governed by the Einstein relativistic equation for total mass-energy. Its calculated photon emissions are all in excellent agreement with experimental data and, of course, in agreement with those -K calculations by Neils Bohr 100 years ago. Problem solved!
Zhou, Xia-Yu; Rong, Chunying; Lu, Tian; Zhou, Panpan; Liu, Shubin
2016-05-26
How to accurately predict electronic properties of a Columbic system with the electron density obtained from experiments such as X-ray crystallography is still an unresolved problem. The information-theoretic approach recently developed in the framework of density functional reactivity theory is one of the efforts to address the issue. In this work, using 27 atoms and 41 molecules as illustrative examples, we present a study to demonstrate that one is able to satisfactorily describe such electronic properties as the total energy and its components with information-theoretic quantities like Shannon entropy, Fisher information, Ghosh-Berkowitz-Parr entropy, and Onicescu information energy. Closely related to the earlier attempt of expanding density functionals using simple homogeneous functionals, this work not only confirms Nagy's proof that Shannon entropy alone should contain all the information needed to adequately describe an electronic system but also provides a feasible pathway to map the relationship between the experimentally available electron density and various electronic properties for Columbic systems such as atoms and molecules. Extensions to other electronic properties are straightforward.
Ultrafast demagnetization in Ni: theory of magneto-optics for non-equilibrium electron distributions
Energy Technology Data Exchange (ETDEWEB)
Oppeneer, P M [Leibniz-Institute of Solid State and Materials Research, PO Box 27006, D-01171 Dresden (Germany); Liebsch, A [Institut fuer Festkoerperforschung, Forschungszentrum Juelich, D-52425 Juelich (Germany)
2004-08-04
The sensitivity of the magneto-optical Kerr response to electronic thermalization processes in ultrafast pump-probe experiments is studied by evaluating the complex conductivity tensor of Ni for non-equilibrium electron distributions. The electronic structure and optical matrix elements are calculated within density functional theory. To account for the electronic redistributions generated by the intense pump-laser pulse during the initial stages of electronic thermalization, two kinds of model electron distributions are considered which mimic the so-called dichroic bleaching or state-blocking effect. Thus, certain optical transitions which are allowed under equilibrium conditions are not accessible to the probe laser. It is shown that the conductivity tensor and the complex Kerr angle can be modified substantially by the non-equilibrium electron distributions. Moreover, in striking contrast to the case for ordinary equilibrium conditions, the Kerr rotation and ellipticity are no longer proportional to the magnetization of the sample. The Kerr response at ultrashort times can therefore not be taken as a measure of demagnetization.
One-Body Potential Theory of Molecules and Solids Modified Semiempirically for Electron Correlation
International Nuclear Information System (INIS)
March, N.H.
2010-08-01
The study of Cordero, March and Alonso (CMA) for four spherical atoms, Be,Ne,Mg and Ar, semiempirically fine-tunes the Hartree-Fock (HF) ground-state electron density by inserting the experimentally determined ionization potentials. The present Letter, first of all, relates this approach to the very recent work of Bartlett 'towards an exact correlated orbital theory for electrons'. Both methods relax the requirement of standard DFT that a one-body potential shall generate the exact ground-state density, though both work with high quality approximations. Unlike DFT, the CMA theory uses a modified HF non-local potential. It is finally stressed that this potential generates also an idempotent Dirac density matrix. The CMA approach is thereby demonstrated to relate, albeit approximately, to the DFT exchange-correlation potential. (author)
Weatherford, Charles A.
1993-01-01
One version of the multichannel theory for electron-target scattering based on the Schwinger variational principle, the SMC method, requires the introduction of a projection parameter. The role of the projection parameter a is investigated and it is shown that the principal-value operator in the SMC equation is Hermitian regardless of the value of a as long as it is real and nonzero. In a basis that is properly orthonormalizable, the matrix representation of this operator is also Hermitian. The use of such basis is consistent with the Schwinger variational principle because the Lippmann-Schwinger equation automatically builds in the correct boundary conditions. Otherwise, an auxiliary condition needs to be introduced, and Takatsuka and McKoy's original value of a is one of the three possible ways to achieve Hermiticity. In all cases but one, a can be uncoupled from the Hermiticity condition and becomes a free parameter. An equation for a based on the variational stability of the scattering amplitude is derived; its solution has an interesting property that the scattering amplitude from a converged SMC calculation is independent of the choice of a even though the SMC operator itself is a-dependent. This property provides a sensitive test of the convergence of the calculation. For a static-exchange calculation, the convergence requirement only depends on the completeness of the one-electron basis, but for a general multichannel case, the a-invariance in the scattering amplitude requires both the one-electron basis and the N plus 1-electron basis to be complete. The role of a in the SMC equation and the convergence property are illustrated using two examples: e-CO elastic scattering in the static-exchange approximation, and a two-state treatment of the e-H2 Chi(sup 1)Sigma(sub g)(+) yields b(sup 3)Sigma(sub u)(+) excitation.
Quantum theory of the electronic and optical properties of low-dimensional semiconductor systems
Lau, Wayne Heung
This thesis examines the electronic and optical properties of low-dimensional semiconductor systems. A theory is developed to study the electron-hole generation-recombination process of type-II semimetallic semiconductor heterojunctions based on a 3 x 3 k·p matrix Hamiltonian (three-band model) and an 8 x 8 k·p matrix Hamiltonian (eight-band model). A novel electron-hole generation and recombination process, which is called activationless generation-recombination process, is predicted. It is demonstrated that the current through the type-II semimetallic semiconductor heterojunctions is governed by the activationless electron-hole generation-recombination process at the heterointerfaces, and that the current-voltage characteristics are essentially linear. A qualitative agreement between theory and experiments is observed. The numerical results of the eight-band model are compared with those of the threeband model. Based on a lattice gas model, a theory is developed to study the influence of a random potential on the ionization equilibrium conditions for bound electron-hole pairs (excitons) in III--V semiconductor heterostructures. It is demonstrated that ionization equilibrium conditions for bound electron-hole pairs change drastically in the presence of strong disorder. It is predicted that strong disorder promotes dissociation of excitons in III--V semiconductor heterostructures. A theory of polariton (photon dressed by phonon) spontaneous emission in a III--V semiconductor doped with semiconductor quantum dots (QDs) or quantum wells (QWs) is developed. For the first time, superradiant and subradiant polariton spontaneous emission phenomena in a polariton-QD (QW) coupled system are predicted when the resonance energies of the two identical QDs (QWs) lie outside the polaritonic energy gap. It is also predicted that when the resonance energies of the two identical QDs (QWs) lie inside the polaritonic energy gap, spontaneous emission of polariton in the polariton
Weak coupling theory of the ripplon limited mobility of a 2-D electron lattice
International Nuclear Information System (INIS)
Dahm, A.J.; Mehrotra, R.
1981-01-01
The one ripplon-n phonon scattering contribution to the mobility of a 2D electron lattice supported by a liquid helium substrate is calculated in first order perturbation theory to all orders of n in the weak coupling limit. The Debye Waller factor is shown to limit the momentum transfer at large ripplon wave-vectors and high temperatures causing a minimum in the mobility as a function of temperature. (orig.)
Integrating clinical theory and practice in an epilepsy-specific electronic patient record.
LENUS (Irish Health Repository)
Breen, Patricia
2009-01-01
This study\\'s objective was to assess the usability of the epilepsy history module of the electronic patient record, developed at Beaumont Hospital, and to identify opportunities for improvement. Observation, interview and document analysis methods were used. Results indicated that the module was useable but the design did not work as well in practice as anticipated by theory. The next iteration of the module included identified enhancements; this iteration is currently in use.
Theory and computation of the rate of multiphoton two-electron ionization via the direct mechanism
Energy Technology Data Exchange (ETDEWEB)
Mercouris, Theodoros; Haritos, Costas [Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Athens (Greece)]. E-mails: thmerc@eie.gr; kharit@eie.gr; Nicolaides, Cleanthes A. [Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Athens (GR) and Physics Department, National Technical University, Athens (Greece)]. E-mail: can@eie.gr
2001-10-14
This paper discusses aspects of the physics and the computation of rates of multiphoton two-electron ionization of polyelectronic atoms within a non-perturbative, time-independent framework. A fundamental characteristic of the theory is that the physically significant features of the spectrum, of electronic structure and of free-electron channels enter systematically in an N-electron field-dressed resonance trial wavefunction. This many-electron, many-photon theory produces the rate of a particular field-induced process as the imaginary part of a frequency- and intensity-dependent complex eigenvalue obtained from the solution of a suitably constructed non-Hermitian Hamiltonian matrix. The notion of direct two-electron ionization is expressed in terms of a specific form of the trial wavefunction, which consists of configurations with real and complex square-integrable functions, subject to orthogonality constraints so as to exclude the participation of single-ionization channels, assumed to contribute mainly to the sequential path. The applications were done to the two-electron ejection from He by the direct absorption of two linearly polarized photons (photon energy in the range 35.0-55.0 eV) and to H{sup -} from the direct and the sequential absorption of four, three, two and one photons (photon energy in the range 4.08-15.00 eV). The comparison between the rates of the two paths in H{sup -}, for photon energies 7.18-10.5 eV, shows that the direct rate dominates. We also show that in the orbital Hartree-Fock approximation to the initial state, the frequency-dependent rates at the intensity of 1x10{sup 13} W cm{sup -2} differ from those obtained with a correlated wavefunction by about two orders of magnitude. (author)
Phase changes in f-electron metals: discrepancies between experiment and theory
International Nuclear Information System (INIS)
Akella, Jagannadham; Weir, Samuel T.; Ruddle, Chantel
1997-01-01
Using a diamond-anvil cell (DAC) phase transformation and equation of state (EOS) at room temperature for some lanthanides and actinides were studied to multimegabar (megabar = 100 GPa) pressures. Experimental data are compared with the theoretically predicted crystal structural changes and the pressure-volume relationships. A generalized trend for the phase transformations in the lanthanides can be seen, which has broad agreement with theory. There is a general agreement between theory and experiment for the structural changes in the lighter actinides, however in detail there are some discrepancies still. We conclude that an accurate and robust theoretical base for predicting the phase transformations in the f-electron metals can be developed by incorporating the DAC data as markers for fine tuning the theory. (author)
Hoyer, Chad E; Ghosh, Soumen; Truhlar, Donald G; Gagliardi, Laura
2016-02-04
A correct description of electronically excited states is critical to the interpretation of visible-ultraviolet spectra, photochemical reactions, and excited-state charge-transfer processes in chemical systems. We have recently proposed a theory called multiconfiguration pair-density functional theory (MC-PDFT), which is based on a combination of multiconfiguration wave function theory and a new kind of density functional called an on-top density functional. Here, we show that MC-PDFT with a first-generation on-top density functional performs as well as CASPT2 for an organic chemistry database including valence, Rydberg, and charge-transfer excitations. The results are very encouraging for practical applications.
A self-consistent nonlinear theory of resistive-wall instability in a relativistic electron beam
International Nuclear Information System (INIS)
Uhm, H.S.
1994-01-01
A self-consistent nonlinear theory of resistive-wall instability is developed for a relativistic electron beam propagating through a grounded cylindrical resistive tube. The theory is based on the assumption that the frequency of the resistive-wall instability is lower than the cutoff frequency of the waveguide. The theory is concentrated on study of the beam current modulation directly related to the resistive-wall klystron, in which a relativistic electron beam is modulated at the first cavity and propagates downstream through the resistive wall. Because of the self-excitation of the space charge waves by the resistive-wall instability, a highly nonlinear current modulation of the electron beam is accomplished as the beam propagates downstream. A partial integrodifferential equation is obtained in terms of the initial energy modulation (ε), the self-field effects (h), and the resistive-wall effects (κ). Analytically investigating the partial integrodifferential equation, a scaling law of the propagation distance z m at which the maximum current modulation occurs is obtained. It is found in general that the self-field effects dominate over the resistive-wall effects at the beginning of the propagation. As the beam propagates farther downstream, the resistive-wall effects dominate. Because of a relatively large growth rate of the instability, the required tube length of the klystron is short for most applications
International Nuclear Information System (INIS)
Sundararaman, Ravishankar; Goddard, William A. III; Arias, Tomas A.
2017-01-01
First-principles calculations combining density-functional theory and continuum solvation models enable realistic theoretical modeling and design of electrochemical systems. When a reaction proceeds in such systems, the number of electrons in the portion of the system treated quantum mechanically changes continuously, with a balancing charge appearing in the continuum electrolyte. A grand-canonical ensemble of electrons at a chemical potential set by the electrode potential is therefore the ideal description of such systems that directly mimics the experimental condition. We present two distinct algorithms: a self-consistent field method and a direct variational free energy minimization method using auxiliary Hamiltonians (GC-AuxH), to solve the Kohn-Sham equations of electronic density-functional theory directly in the grand canonical ensemble at fixed potential. Both methods substantially improve performance compared to a sequence of conventional fixed-number calculations targeting the desired potential, with the GC-AuxH method additionally exhibiting reliable and smooth exponential convergence of the grand free energy. Lastly, we apply grand-canonical density-functional theory to the under-potential deposition of copper on platinum from chloride-containing electrolytes and show that chloride desorption, not partial copper monolayer formation, is responsible for the second voltammetric peak.
Sundararaman, Ravishankar; Goddard, William A.; Arias, Tomas A.
2017-03-01
First-principles calculations combining density-functional theory and continuum solvation models enable realistic theoretical modeling and design of electrochemical systems. When a reaction proceeds in such systems, the number of electrons in the portion of the system treated quantum mechanically changes continuously, with a balancing charge appearing in the continuum electrolyte. A grand-canonical ensemble of electrons at a chemical potential set by the electrode potential is therefore the ideal description of such systems that directly mimics the experimental condition. We present two distinct algorithms: a self-consistent field method and a direct variational free energy minimization method using auxiliary Hamiltonians (GC-AuxH), to solve the Kohn-Sham equations of electronic density-functional theory directly in the grand canonical ensemble at fixed potential. Both methods substantially improve performance compared to a sequence of conventional fixed-number calculations targeting the desired potential, with the GC-AuxH method additionally exhibiting reliable and smooth exponential convergence of the grand free energy. Finally, we apply grand-canonical density-functional theory to the under-potential deposition of copper on platinum from chloride-containing electrolytes and show that chloride desorption, not partial copper monolayer formation, is responsible for the second voltammetric peak.
Sundararaman, Ravishankar; Goddard, William A; Arias, Tomas A
2017-03-21
First-principles calculations combining density-functional theory and continuum solvation models enable realistic theoretical modeling and design of electrochemical systems. When a reaction proceeds in such systems, the number of electrons in the portion of the system treated quantum mechanically changes continuously, with a balancing charge appearing in the continuum electrolyte. A grand-canonical ensemble of electrons at a chemical potential set by the electrode potential is therefore the ideal description of such systems that directly mimics the experimental condition. We present two distinct algorithms: a self-consistent field method and a direct variational free energy minimization method using auxiliary Hamiltonians (GC-AuxH), to solve the Kohn-Sham equations of electronic density-functional theory directly in the grand canonical ensemble at fixed potential. Both methods substantially improve performance compared to a sequence of conventional fixed-number calculations targeting the desired potential, with the GC-AuxH method additionally exhibiting reliable and smooth exponential convergence of the grand free energy. Finally, we apply grand-canonical density-functional theory to the under-potential deposition of copper on platinum from chloride-containing electrolytes and show that chloride desorption, not partial copper monolayer formation, is responsible for the second voltammetric peak.
Two-electron Rabi oscillations in real-time time-dependent density-functional theory.
Habenicht, Bradley F; Tani, Noriyuki P; Provorse, Makenzie R; Isborn, Christine M
2014-11-14
We investigate the Rabi oscillations of electrons excited by an applied electric field in several simple molecular systems using time-dependent configuration interaction (TDCI) and real-time time-dependent density-functional theory (RT-TDDFT) dynamics. While the TDCI simulations exhibit the expected single-electron Rabi oscillations at a single resonant electric field frequency, Rabi oscillations in the RT-TDDFT simulations are a two-electron process. The existence of two-electron Rabi oscillations is determined both by full population inversion between field-free molecular orbitals and the behavior of the instantaneous dipole moment during the simulations. Furthermore, the Rabi oscillations in RT-TDDFT are subject to an intensity threshold of the electric field, below which Rabi oscillations do not occur and above which the two-electron Rabi oscillations occur at a broad range of frequencies. It is also shown that at field intensities near the threshold intensity, the field frequency predicted to induce Rabi oscillations by linear response TDDFT only produces detuned Rabi oscillations. Instead, the field frequency that yields the full two-electron population inversion and Rabi oscillation behavior is shown to be the average of single-electron transition frequencies from the ground S0 state and the doubly-excited S2 state. The behavior of the two-electron Rabi oscillations is rationalized via two possible models. The first model is a multi-photon process that results from the electric field interacting with the three level system such that three level Rabi oscillations may occur. The second model suggests that the mean-field nature of RT-TDDFT induces paired electron propagation.
Two-electron Rabi oscillations in real-time time-dependent density-functional theory
International Nuclear Information System (INIS)
Habenicht, Bradley F.; Tani, Noriyuki P.; Provorse, Makenzie R.; Isborn, Christine M.
2014-01-01
We investigate the Rabi oscillations of electrons excited by an applied electric field in several simple molecular systems using time-dependent configuration interaction (TDCI) and real-time time-dependent density-functional theory (RT-TDDFT) dynamics. While the TDCI simulations exhibit the expected single-electron Rabi oscillations at a single resonant electric field frequency, Rabi oscillations in the RT-TDDFT simulations are a two-electron process. The existence of two-electron Rabi oscillations is determined both by full population inversion between field-free molecular orbitals and the behavior of the instantaneous dipole moment during the simulations. Furthermore, the Rabi oscillations in RT-TDDFT are subject to an intensity threshold of the electric field, below which Rabi oscillations do not occur and above which the two-electron Rabi oscillations occur at a broad range of frequencies. It is also shown that at field intensities near the threshold intensity, the field frequency predicted to induce Rabi oscillations by linear response TDDFT only produces detuned Rabi oscillations. Instead, the field frequency that yields the full two-electron population inversion and Rabi oscillation behavior is shown to be the average of single-electron transition frequencies from the ground S 0 state and the doubly-excited S 2 state. The behavior of the two-electron Rabi oscillations is rationalized via two possible models. The first model is a multi-photon process that results from the electric field interacting with the three level system such that three level Rabi oscillations may occur. The second model suggests that the mean-field nature of RT-TDDFT induces paired electron propagation
Theory of Coherent Radiation from a Grating-Waveguide Free-Electron Laser
Huang, Y C
2005-01-01
A Smith-Purcell radiator produces transversely asymmetric radiation modes due to the arrangement of a grating on one side of the electron beam. This asymmetric output could limit the usefulness of such a device in the THz spectrum where diffraction of waves is severe. It is possible to produce symmetric radiation from a double-grating waveguide driven by an electron beam traversing the waveguide gap. We derive a theory that describes the modes and small signal gain of this novel grating-waveguide free-electron laser. Our theory shows that extremely high laser gain is obtained when the electron beam is phase matched to the middle or edge of the radiation bands where the radiation modes have zero group velocity. In our calculation we obtained 66dB/mm gain at 298 µm for a 5 mA, 30keV driving beam in a grating waveguide with a 50-micron, 40% duty-cycle grating period, a 60-micron groove depth, and a 150 micron waveguide gap. This extremely high gain indicates that this novel device establishes resonance...
Density functional theory and an experimentally-designed energy functional of electron density.
Miranda, David A; Bueno, Paulo R
2016-09-21
We herein demonstrate that capacitance spectroscopy (CS) experimentally allows access to the energy associated with the quantum mechanical ground state of many-electron systems. Priorly, electrochemical capacitance, C [small mu, Greek, macron] [ρ], was previously understood from conceptual and computational density functional theory (DFT) calculations. Thus, we herein propose a quantum mechanical experiment-based variational method for electron charging processes based on an experimentally-designed functional of the ground state electron density. In this methodology, the electron state density, ρ, and an energy functional of the electron density, E [small mu, Greek, macron] [ρ], can be obtained from CS data. CS allows the derivative of the electrochemical potential with respect to the electron density, (δ[small mu, Greek, macron][ρ]/δρ), to be obtained as a unique functional of the energetically minimised system, i.e., β/C [small mu, Greek, macron] [ρ], where β is a constant (associated with the size of the system) and C [small mu, Greek, macron] [ρ] is an experimentally observable quantity. Thus the ground state energy (at a given fixed external potential) can be obtained simply as E [small mu, Greek, macron] [ρ], from the experimental measurement of C [small mu, Greek, macron] [ρ]. An experimental data-set was interpreted to demonstrate the potential of this quantum mechanical experiment-based variational principle.
International Nuclear Information System (INIS)
Dale, Stephen G.; Johnson, Erin R.
2015-01-01
Exploration of the solvated electron phenomena using density-functional theory (DFT) generally results in prediction of a localised electron within an induced solvent cavity. However, it is well known that DFT favours highly delocalised charges, rendering the localisation of a solvated electron unexpected. We explore the origins of this counterintuitive behaviour using a model Kevan-structure system. When a polarisable-continuum solvent model is included, it forces electron localisation by introducing a strong energetic bias that favours integer charges. This results in the formation of a large energetic barrier for charge-hopping and can cause the self-consistent field to become trapped in local minima thus converging to stable solutions that are higher in energy than the ground electronic state. Finally, since the bias towards integer charges is caused by the polarisable continuum, these findings will also apply to other classical polarisation corrections, as in combined quantum mechanics and molecular mechanics (QM/MM) methods. The implications for systems beyond the solvated electron, including cationic DNA bases, are discussed
Relations of secondary electron emission to microdosimetry and applications to two-target theory
International Nuclear Information System (INIS)
Forsberg, B.J.; Burlin, T.E.
1978-01-01
Secondary electron emission has been suggested as a phenomenon that offers considerable potential for microdosimetric studies (Burlin, 1973). This potential is examined further through a theoretical study. Previous work on the stochastic nature of secondary electron emission is reviewed and in particular a Monte Carlo programme of McDonald, Lamki and Delaney (1971, 1973) is developed. Lineal energy distributions are presented for tissue equivalent volumes of about 5nm in three materials for different electron energies. The dose mean of lineal energy and the frequency mean of lineal energy are calculated and these results for volumes with linear dimension of a few nanometers are compared with results of Bengtsson and Lindborg (1974), Braby and Ellett (1971) and Dvorak (1975). Several authors have suggested that some radiobiological effects may result from energy deposition in two different targets. An experimental investigation using proportional counter measurements to simulate two-target theory has been reported. In this paper an alternative technique to twin-proportional counter measurements, based on the secondary electron emission from the two sides of a thin foil is discussed. The extended version of the programme calculates the coincident P(nsub(i),nsub(e)) distribution, that is the number of secondary electrons pair (nsub(i), nsub(e)) is recorded, where nsub(i) is the number of secondary electrons leaving the incident side and nsub(e) is leaving the exit side of the foil simultaneously
Energy Technology Data Exchange (ETDEWEB)
Dale, Stephen G., E-mail: sdale@ucmerced.edu [Chemistry and Chemical Biology, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California 95343 (United States); Johnson, Erin R., E-mail: erin.johnson@dal.ca [Department of Chemistry, Dalhousie University, 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2 (Canada)
2015-11-14
Exploration of the solvated electron phenomena using density-functional theory (DFT) generally results in prediction of a localised electron within an induced solvent cavity. However, it is well known that DFT favours highly delocalised charges, rendering the localisation of a solvated electron unexpected. We explore the origins of this counterintuitive behaviour using a model Kevan-structure system. When a polarisable-continuum solvent model is included, it forces electron localisation by introducing a strong energetic bias that favours integer charges. This results in the formation of a large energetic barrier for charge-hopping and can cause the self-consistent field to become trapped in local minima thus converging to stable solutions that are higher in energy than the ground electronic state. Finally, since the bias towards integer charges is caused by the polarisable continuum, these findings will also apply to other classical polarisation corrections, as in combined quantum mechanics and molecular mechanics (QM/MM) methods. The implications for systems beyond the solvated electron, including cationic DNA bases, are discussed.
Polo, Victor; Andres, Juan; Berski, Slawomir; Domingo, Luis R; Silvi, Bernard
2008-08-07
Thom's catastrophe theory applied to the evolution of the topology of the electron localization function (ELF) gradient field constitutes a way to rationalize the reorganization of electron pairing and a powerful tool for the unambiguous determination of the molecular mechanisms of a given chemical reaction. The identification of the turning points connecting the ELF structural stability domains along the reaction pathway allows a rigorous characterization of the sequence of electron pair rearrangements taking place during a chemical transformation, such as multiple bond forming/breaking processes, ring closure processes, creation/annihilation of lone pairs, transformations of C-C multiple bonds into single ones. The reaction mechanism of some relevant organic reactions: Diels-Alder, 1,3-dipolar cycloaddition and Cope rearrangement are reviewed to illustrate the potential of the present approach.
Many-body theory of electron-positron interaction in metallic lithium
Energy Technology Data Exchange (ETDEWEB)
Stachowiak, H.; Boronski, E.; Banach, G. [Polska Akademia Nauk, Wroclaw (Poland). Inst. Niskich Temperatur i Badan Strukturalnych
1997-12-31
The development of the partial density amplitude approach to the electronic structure of simple metals offers the possibility to perform direct many-body calculations of the electron-positron interaction in these materials. A theory of this interaction based on the hypernetted-chain formalism is proposed and applied to lithium. It leads to a nonlinear three-dimensional integro-differential equation for the enhancement amplitude. This equation is solved for two cases in which it reduces to one dimension. The relation between the results obtained in this way for the annihilation rate and the predictions of the local density approximation and other approaches is studied. The role of core electrons in the interaction is explained. (orig.) 8 refs.
International Nuclear Information System (INIS)
Sun, Shih-Jye; Lin, Ken-Huang; Li, Jia-Yun; Ju, Shin-Pon
2014-01-01
The simulated annealing basin-hopping method incorporating the penalty function was used to predict the lowest-energy structures for ultrathin tungsten nanowires and nanotubes of different sizes. These predicted structures indicate that tungsten one-dimensional structures at this small scale do not possess B.C.C. configuration as in bulk tungsten material. In order to analyze the relationship between multi-shell geometries and electronic transfer, the electronic and structural properties of tungsten wires and tubes including partial density of state and band structures which were determined and analyzed by quantum chemistry calculations. In addition, in order to understand the application feasibility of these nanowires and tubes on nano-devices such as field emitters or chemical catalysts, the electronic stability of these ultrathin tungsten nanowires was also investigated by density functional theory calculations.
Huang, Yan R; Ning, Chuan G; Deng, Jing K; Deleuze, Michael S
2008-05-07
A complete study of the valence electronic structure and related electronic excitation properties of cyclopentene in its C(s) ground state geometry is presented. Ionization spectra obtained from this compound by means of photoelectron spectroscopy (He I and He II) and electron momentum spectroscopy have been analyzed in details up to electron binding energies of 30 eV using one-particle Green's function (1p-GF) theory along with the outer-valence (OVGF) and the third-order algebraic diagrammatic construction [ADC(3)] schemes. The employed geometries derive from DFT/B3LYP calculations in conjunction with the aug-cc-pVTZ basis set, and closely approach the structures inferred from experiments employing microwave spectroscopy or electron diffraction in the gas phase. The 1p-GF/ADC(3) calculations indicate that the orbital picture of ionization breaks down at electron binding energies larger than approximately 17 eV in the inner-valence region, and that the outer-valence 7a' orbital is also subject to a significant dispersion of the ionization intensity over shake-up states. This study confirms further the rule that OVGF pole strengths smaller than 0.85 foretell a breakdown of the orbital picture of ionization at the ADC(3) level. Spherically averaged (e, 2e) electron momentum distributions at an electron impact energy of 1200 eV that were experimentally inferred from an angular analysis of EMS intensities have been interpreted by comparison with accurate simulations employing ADC(3) Dyson orbitals. Very significant discrepancies were observed with momentum distributions obtained from several outer-valence ionization bands using standard Kohn-Sham orbitals.
Theory and simulation of an inverse free-electron laser experiment
Gou, S. K.; Bhattacharjee, A.; Fang, J.-M.; Marshall, T. C.
1997-03-01
An experimental demonstration of the acceleration of electrons using a high-power CO2 laser interacting with a relativistic electron beam moving along a wiggler has been carried out at the Accelerator Test Facility of the Brookhaven National Laboratory [Phys. Rev. Lett. 77, 2690 (1996)]. The data generated by this inverse free-electron-laser (IFEL) experiment are studied by means of theory and simulation. Included in the simulations are such effects as: a low-loss metallic waveguide with a dielectric coating on the walls; multi-mode coupling due to self-consistent interaction between the electrons and the optical wave; space charge; energy spread of the electrons; and arbitrary wiggler-field profile. Two types of wiggler profile are considered: a linear taper of the period, and a step-taper of the period. (The period of the wiggler is ˜3 cm, its magnetic field is ˜1 T, and the wiggler length is 0.47 m.) The energy increment of the electrons (˜1-2%) is analyzed in detail as a function of laser power, wiggler parameters, and the initial beam energy (˜40 MeV). At a laser power level ˜0.5 Gw, the simulation results on energy gain are in reasonable agreement with the experimental results. Preliminary results on the electron energy distribution at the end of the IFEL are presented. Whereas the experiment produces a near-monotone distribution of electron energies with the peak shifted to higher energy, the simulation shows a more structured and non-monotonic distribution at the end of the wiggler. Effects that may help reconcile these differences are considered.
A universal equation for the electronic stopping of ions in solids
International Nuclear Information System (INIS)
Montenegro, E.C.; Cruz, S.A.; Vargas-Aburto, C.
1982-09-01
An analytical equation for the electronic stopping of ions in solids for non-relativistic velocities, that has no adjustable parameters, is obtained in a semi-phenomenological manner. The very good agreement with experiment gives support to the physical arguments used in its derivation. (Author) [pt
Theory of bright-field scanning transmission electron microscopy for tomography
International Nuclear Information System (INIS)
Levine, Zachary H.
2005-01-01
Radiation transport theory is applied to electron microscopy of samples composed of one or more materials. The theory, originally due to Goudsmit and Saunderson, assumes only elastic scattering and an amorphous medium dominated by atomic interactions. For samples composed of a single material, the theory yields reasonable parameter-free agreement with experimental data taken from the literature for the multiple scattering of 300-keV electrons through aluminum foils up to 25 μm thick. For thin films, the theory gives a validity condition for Beer's law. For thick films, a variant of Moliere's theory [V. G. Moliere, Z. Naturforschg. 3a, 78 (1948)] of multiple scattering leads to a form for the bright-field signal for foils in the multiple-scattering regime. The signal varies as [t ln(e 1-2γ t/τ)] -1 where t is the path length of the beam, τ is the mean free path for elastic scattering, and γ is Euler's constant. The Goudsmit-Saunderson solution interpolates numerically between these two limits. For samples with multiple materials, elemental sensitivity is developed through the angular dependence of the scattering. From the elastic scattering cross sections of the first 92 elements, a singular-value decomposition of a vector space spanned by the elastic scattering cross sections minus a delta function shows that there is a dominant common mode, with composition-dependent corrections of about 2%. A mathematically correct reconstruction procedure beyond 2% accuracy requires the acquisition of the bright-field signal as a function of the scattering angle. Tomographic reconstructions are carried out for three singular vectors of a sample problem with four elements Cr, Cu, Zr, and Te. The three reconstructions are presented jointly as a color image; all four elements are clearly identifiable throughout the image
Vázquez Molina, Joan
2017-01-01
This PhD thesis is submitted as a \\emph{compendium} of the articles \\cite{NS, holographic, topological}. The following has been adapted from their abstracts. Quantum mechanics has been argued to be a coarse--graining of some underlying deterministic theory. Here we support this view by establishing mappings between non-relativistic quantum mechanics and thermodynamic theories, since the latter are the paradigm of an emergent theory. First, we map certain solutions of the Schroedinger ...
Huhn, William Paul; Lange, Björn; Yu, Victor; Blum, Volker; Lee, Seyong; Yoon, Mina
Density-functional theory has been well established as the dominant quantum-mechanical computational method in the materials community. Large accurate simulations become very challenging on small to mid-scale computers and require high-performance compute platforms to succeed. GPU acceleration is one promising approach. In this talk, we present a first implementation of all-electron density-functional theory in the FHI-aims code for massively parallel GPU-based platforms. Special attention is paid to the update of the density and to the integration of the Hamiltonian and overlap matrices, realized in a domain decomposition scheme on non-uniform grids. The initial implementation scales well across nodes on ORNL's Titan Cray XK7 supercomputer (8 to 64 nodes, 16 MPI ranks/node) and shows an overall speed up in runtime due to utilization of the K20X Tesla GPUs on each Titan node of 1.4x, with the charge density update showing a speed up of 2x. Further acceleration opportunities will be discussed. Work supported by the LDRD Program of ORNL managed by UT-Battle, LLC, for the U.S. DOE and by the Oak Ridge Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC05-00OR22725.
Haule, Kristjan
2018-04-01
The Dynamical Mean Field Theory (DMFT) in combination with the band structure methods has been able to address reach physics of correlated materials, such as the fluctuating local moments, spin and orbital fluctuations, atomic multiplet physics and band formation on equal footing. Recently it is getting increasingly recognized that more predictive ab-initio theory of correlated systems needs to also address the feedback effect of the correlated electronic structure on the ionic positions, as the metal-insulator transition is almost always accompanied with considerable structural distortions. We will review recently developed extension of merger between the Density Functional Theory (DFT) and DMFT method, dubbed DFT+ embedded DMFT (DFT+eDMFT), whichsuccessfully addresses this challenge. It is based on the stationary Luttinger-Ward functional to minimize the numerical error, it subtracts the exact double-counting of DFT and DMFT, and implements self-consistent forces on all atoms in the unit cell. In a few examples, we will also show how the method elucidated the important feedback effect of correlations on crystal structure in rare earth nickelates to explain the mechanism of the metal-insulator transition. The method showed that such feedback effect is also essential to understand the dynamic stability of the high-temperature body-centered cubic phase of elemental iron, and in particular it predicted strong enhancement of the electron-phonon coupling over DFT values in FeSe, which was very recently verified by pioneering time-domain experiment.
Berry curvature, orbital moment, and effective quantum theory of electrons in electromagnetic fields
International Nuclear Information System (INIS)
Chang, M-C; Niu Qian
2008-01-01
Berry curvature and orbital moment of the Bloch state are two basic ingredients, in addition to the band energy, that must be included in the formulation of semiclassical dynamics of electrons in crystals, in order to give proper account of thermodynamic and transport properties to first order in the electromagnetic field. These quantities are gauge invariant and have direct physical significance as demonstrated by numerous applications in recent years. Generalization to the case of degenerate bands has also been achieved recently, with important applications in spin-dependent transport. The reader is assured that a knowledge of these ingredients of the semiclassical dynamics is also sufficient for the construction of an effective quantum theory, valid to the same order of the field, using a new quantization procedure that generalizes the venerable Peierls substitution rule. We cite the relativistic Dirac electron and the carrier in semiconductors as two prime examples to demonstrate our theory and compare with previous work on such systems. We also establish general relations between different levels of effective theories in a hierarchy. (topical review)
Quantum theory of the laser radiation scattering by electrons in magnetic fields
International Nuclear Information System (INIS)
Rochlin, H.
1981-08-01
A system composed of an electron in a static magnetic field interacting with the quantized electromagnetic field, within the electric-dipole and the nonrelativistic approximations (with a cutoff in momentum space) is considered. The Heisenberg equations are solved exactly and the time evolution of the electric field is determined. This result is then used to obtain the spectrum of the scattered radiation when the initial state of the field is coherent, aplying the theory of photodetection. This theory is thoroughly discussed. Several expressions proposed in the literature for the time-dependent spectrum are compared and conditions for the equivalence of these expressions are analyzed. Moreover, inaccuracies in previous treatments of the theory of photodetection are corrected. The results allow the line shape of the scattered radiation to be analyzed for magnetic fields up to 10 12 G. The quantization of the eletromagnetic field allows one to consider the role of the natural line width, which becomes important near ressonance. In particular, it is analyzed the dependence of the line width with the magnetic field. This treatment includes the renormalization of the electron mass, which keeps the results finite when the cutoff goes to infinity. (Author) [pt
Holomorphic Hartree-Fock Theory: The Nature of Two-Electron Problems.
Burton, Hugh G A; Gross, Mark; Thom, Alex J W
2018-02-13
We explore the existence and behavior of holomorphic restricted Hartree-Fock (h-RHF) solutions for two-electron problems. Through algebraic geometry, the exact number of solutions with n basis functions is rigorously identified as 1 / 2 (3 n - 1), proving that states must exist for all molecular geometries. A detailed study on the h-RHF states of HZ (STO-3G) then demonstrates both the conservation of holomorphic solutions as geometry or atomic charges are varied and the emergence of complex h-RHF solutions at coalescence points. Using catastrophe theory, the nature of these coalescence points is described, highlighting the influence of molecular symmetry. The h-RHF states of HHeH 2+ and HHeH (STO-3G) are then compared, illustrating the isomorphism between systems with two electrons and two electron holes. Finally, we explore the h-RHF states of ethene (STO-3G) by considering the π electrons as a two-electron problem and employ NOCI to identify a crossing of the lowest energy singlet and triplet states at the perpendicular geometry.
Modeling the Electron Transport in Nanostructures by Using the Concept of BIons in M-theory
Sepehri, Alireza; Pincak, Richard
2016-10-01
In this paper, using the similarity between quantum tunnels in nanostructures and BIon in M-theory, we propose a new model which considers the process of formation of superconductors in nanostructures. We show that by decreasing the size of nanostructures, emitted photons by electrons connect to each other and form a wormhole-like tunnel. This tunnel is a channel for transporting electron inside the nanostructure. If different wormhole-like tunnels join to each other, one big tunnel is constructed that can be an origin for superconductivity in matter. The superconductor order parameter depends on the size of nanostructure and temperature. Increasing temperature, it is shown that the model matches with quantum theory prescriptions. Also, by applying external electromagnetism, external photons interact with exchanging photons between electrons, exchanging photons deviate from original route and the formation of wormhole-like tunnels inside a nanostructure is prevented. Finally, it is shown that the origin of electrodynamics and gravity are the same and thus, the phrase of wormhole can be applied for appeared tunnels in nanostructures.
Quasiclassical R-matrix theory of inelastic processes in collisions of electrons with HCl molecules
International Nuclear Information System (INIS)
Fabrikant, I.I.
1991-01-01
The R-matrix theory for the vibrational excitation and dissociative attachment in e-HCl collisions is developed. Only one pole in the R-matrix expansion is included. This allows for making a connection between the R-matrix and the nonlocal-complex-potential theories, and for obtaining the expression for the dissociative-attachment cross section without using the R-matrix radius in the internuclear coordinate. All matrix elements in the equation for the vibrational-excitation and dissociative-attachment amplitudes are calculated using the quasiclassical approach. We study how the results depend on the number of vibrational levels of the neutral molecule included in the theory and show how to exclude the vibrational continuum by a modification of the nonlocal-complex potential. The results for the vibrational-excitation cross sections are extremely sensitive to the behavior of the R-matrix potential curve near the point of crossing this curve with the potential curve of the neutral molecule. Particularly in some cases the cross section at the threshold peak exhibits the boomerang oscillations earlier found for HCl by Domcke [in Aspects of Electron-Molecule Scattering and Photoionization, edited by A. Herzenberg (AIP, New Haven, 1989), p. 169]. The dissociative-attachment cross sections are in reasonable agreement with experiment and with other theories
Nonequilibrium Green's function theory for nonadiabatic effects in quantum electron transport
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.
Reconstructive approaches to one- and two-electron density matrix theory
Herbert, John Michael
Novel computational methods for electronic structure theory are explored, in which the fundamental variable is either the one- or the two-electron reduced density matrix (1- or 2-RDM), rather than the electronic wavefunction. A unifying theme among these methods is density matrix reconstruction, that is, decoupling approximations that express higher-order density matrices as functionals of lower-order ones. On the 2-RDM side, a connected (extensive) version of the Contracted Schrodinger Equation (CSE) is developed, in which the basic unknowns are the RDM cumulants through order four. Reconstruction functionals that neglect the 3- and 4-RDM cumulants are examined and revealed to be significantly less accurate than suggested by previous minimal-basis results. Exact 3-RDM cumulants for some four-electron systems are calculated and found to be comparable in importance to unconnected products of lower-order cumulants. Decoupling approximations for the 3- and 4-RDM cumulants are developed based upon a renormalized, diagrammatic perturbation theory for the three- and four-particle Green's functions, in which the effective, pairwise interaction is extracted from the two-particle cumulant. Diagram rules suitable for both the time-dependent and time-independent versions of this perturbation theory are derived. Reconstructive approaches to natural orbital (1-RDM) functional theory are also examined, wherein the 2-RDM is parametrized in terms of the natural orbitals and their (generally fractional) occupancies. It is demonstrated, at the theorem level, that proposed "corrected Hartree" and "corrected Hartree-Fock" natural orbital functionals necessarily violate positivity of the 2-RDM, which is closely related to their failure to respect antisymmetry. Calculations demonstrate that negative eigenvalues of the 2-RDM are associated with a large, stabilizing (but ultimately spurious) contribution to the energy. Nevertheless, a partially self-interaction-corrected version of the
Theory of Electric-Field Effects on Electron-Spin-Resonance Hyperfine Couplings
International Nuclear Information System (INIS)
Karna, S.P.
1997-01-01
A quantum mechanical theory of the effects of a uniform electric field on electron-spin-resonance hyperfine couplings is presented. The electric-field effects are described in terms of perturbation coefficients which can be used to probe the local symmetry as well as the strength of the electric field at paramagnetic sites in a solid. Results are presented for the first-order perturbation coefficients describing the Bloembergen effect (linear electric-field effect on hyperfine coupling tensor) for the O atom and the OH radical. copyright 1997 The American Physical Society
Seabra, G M; Kaplan, I G; Ortiz, J V
2005-09-15
Corrections to dipole approximation results for angular distributions in photoionization of first-row hydrides have determined by using Dyson orbitals calculated with ab initio electron propagator theory and by considering the full multipole expansion for the incident photon representation. The relative importance of first-order corrections which consist of electric quadrupole and magnetic dipole terms and of higher-order terms has been estimated as a function of photon energy. Multipole corrections to the dipole approximation depend on photon energy and on the characteristics of the Dyson orbitals.
Dynamic scattering theory for dark-field electron holography of 3D strain fields.
Lubk, Axel; Javon, Elsa; Cherkashin, Nikolay; Reboh, Shay; Gatel, Christophe; Hÿtch, Martin
2014-01-01
Dark-field electron holography maps strain in crystal lattices into reconstructed phases over large fields of view. Here we investigate the details of the lattice strain-reconstructed phase relationship by applying dynamic scattering theory both analytically and numerically. We develop efficient analytic linear projection rules for 3D strain fields, facilitating a straight-forward calculation of reconstructed phases from 3D strained materials. They are used in the following to quantify the influence of various experimental parameters like strain magnitude, specimen thickness, excitation error and surface relaxation. © 2013 Elsevier B.V. All rights reserved.
A Review of X-ray Free-Electron Laser Theory
Energy Technology Data Exchange (ETDEWEB)
Huang, Zhirong; /SLAC; Kim, Kwang-Je; /ANL, APS
2006-12-18
High-gain free-electron lasers (FELs) are being developed as extremely bright sources for a next-generation x-ray facility. In this paper, we review the basic theory of the startup, the exponential growth, and the saturation of the high-gain process, emphasizing the self-amplified spontaneous emission (SASE). The radiation characteristics of an x-ray FEL, including its transverse coherence, temporal characteristics, and harmonic content, are discussed. FEL performance in the presence of machine errors and undulator wakefields is examined. Various enhancement schemes through seeding and beam manipulations are summarized.
DEFF Research Database (Denmark)
Hubert, Mickaël; Hedegård, Erik D.; Jensen, Hans Jørgen Aa
2016-01-01
inadequate when the molecule has near-degeneracies and/or low-lying double-excited states. To address these issues we have recently proposed multiconfiguration short-range density-functional theory-MC-srDFT-as a new tool in the toolbox. While initial applications for systems with multireference character......Computational methods that can accurately and effectively predict all types of electronic excitations for any molecular system are missing in the toolbox of the computational chemist. Although various Kohn-Sham density-functional methods (KS-DFT) fulfill this aim in some cases, they become......-srDFT for a selected benchmark set of electronic excitations of organic molecules, covering the most common types of organic chromophores. This investigation confirms the expectation that the MC-srDFT method is accurate for a broad range of excitations and comparable to accurate wave function methods such as CASPT2...
Liu, C; Liu, J; Yao, Y X; Wu, P; Wang, C Z; Ho, K M
2016-10-11
We recently proposed the correlation matrix renormalization (CMR) theory to treat the electronic correlation effects [Phys. Rev. B 2014, 89, 045131 and Sci. Rep. 2015, 5, 13478] in ground state total energy calculations of molecular systems using the Gutzwiller variational wave function (GWF). By adopting a number of approximations, the computational effort of the CMR can be reduced to a level similar to Hartree-Fock calculations. This paper reports our recent progress in minimizing the error originating from some of these approximations. We introduce a novel sum-rule correction to obtain a more accurate description of the intersite electron correlation effects in total energy calculations. Benchmark calculations are performed on a set of molecules to show the reasonable accuracy of the method.
Olbrant, Edgar; Frank, Martin
2010-12-01
In this paper, we study a deterministic method for particle transport in biological tissues. The method is specifically developed for dose calculations in cancer therapy and for radiological imaging. Generalized Fokker-Planck (GFP) theory [Leakeas and Larsen, Nucl. Sci. Eng. 137 (2001), pp. 236-250] has been developed to improve the Fokker-Planck (FP) equation in cases where scattering is forward-peaked and where there is a sufficient amount of large-angle scattering. We compare grid-based numerical solutions to FP and GFP in realistic medical applications. First, electron dose calculations in heterogeneous parts of the human body are performed. Therefore, accurate electron scattering cross sections are included and their incorporation into our model is extensively described. Second, we solve GFP approximations of the radiative transport equation to investigate reflectance and transmittance of light in biological tissues. All results are compared with either Monte Carlo or discrete-ordinates transport solutions.
New foundation of quantum theory
International Nuclear Information System (INIS)
Schmutzer, E.
1976-01-01
A new foundation of quantum theory is given on the basis of the formulated 'Principle of Fundamental Covariance', combining the 'Principle of General Relativity' (coordinate-covariance in space-time) and the 'Principle of Operator-Covariance' (in Hilbert space). The fundamental quantum laws proposed are: (1) time-dependent simultaneous laws of motion for the operators, general states and eigenstates, (2) commutation relations, (3) time-dependent eigenvalue equations. All these laws fulfill the Principle of Fundamental Covariance (in non-relativistic quantum mechanics with restricted coordinate transformations). (author)
Motamarri, Phani; Gavini, Vikram
2018-04-01
We derive the expressions for configurational forces in Kohn-Sham density functional theory, which correspond to the generalized variational force computed as the derivative of the Kohn-Sham energy functional with respect to the position of a material point x . These configurational forces that result from the inner variations of the Kohn-Sham energy functional provide a unified framework to compute atomic forces as well as stress tensor for geometry optimization. Importantly, owing to the variational nature of the formulation, these configurational forces inherently account for the Pulay corrections. The formulation presented in this work treats both pseudopotential and all-electron calculations in a single framework, and employs a local variational real-space formulation of Kohn-Sham density functional theory (DFT) expressed in terms of the nonorthogonal wave functions that is amenable to reduced-order scaling techniques. We demonstrate the accuracy and performance of the proposed configurational force approach on benchmark all-electron and pseudopotential calculations conducted using higher-order finite-element discretization. To this end, we examine the rates of convergence of the finite-element discretization in the computed forces and stresses for various materials systems, and, further, verify the accuracy from finite differencing the energy. Wherever applicable, we also compare the forces and stresses with those obtained from Kohn-Sham DFT calculations employing plane-wave basis (pseudopotential calculations) and Gaussian basis (all-electron calculations). Finally, we verify the accuracy of the forces on large materials systems involving a metallic aluminum nanocluster containing 666 atoms and an alkane chain containing 902 atoms, where the Kohn-Sham electronic ground state is computed using a reduced-order scaling subspace projection technique [P. Motamarri and V. Gavini, Phys. Rev. B 90, 115127 (2014), 10.1103/PhysRevB.90.115127].
Riddlesperger, K L; Beard, M; Flowers, D L; Hisley, S M; Pfeifer, K A; Stiller, J J
1996-09-01
Since the 1980s the electronic domain has become the primary method for academic and professional communication of research and information. Papers relating to theory construction in nursing are a frequently occurring phenomenon within the electronic domain. Theory construction provides the underpinning for the advancement of professional nursing, facilitating the conceptualization of nursing actions leading to theory-based practice and research. The purpose of this study was to address the research question, 'What are the similarities and differences among theory construction papers that are accessible electronically in nursing literature today?' The Cumulative Index to Nursing and Allied Health Literature (CINAHL) was accessed to obtain a listing of papers from which an overall description of the type of theory construction papers being published in the nursing literature today could be determined. A literature search was conducted using the description 'theory construction'. Papers were limited to publication years from 1990 onwards. A total of 125 papers were obtained and read by one of the six authors. Using grounded theory, categories emerged by identification of similarities and differences among the papers. The findings are discussed here along with suggestions for further study. A second purpose of this paper was to present both traditional and non-traditional methods of tapping into the electronic domain when searching for assistance with theory construction.
Correlated electron dynamics and memory in time-dependent density functional theory
International Nuclear Information System (INIS)
Thiele, Mark
2009-01-01
Time-dependent density functional theory (TDDFT) is an exact reformulation of the time-dependent many-electron Schroedinger equation, where the problem of many interacting electrons is mapped onto the Kohn-Sham system of noninteracting particles which reproduces the exact electronic density. In the Kohn-Sham system all non-classical many-body effects are incorporated in the exchange-correlation potential which is in general unknown and needs to be approximated. It is the goal of this thesis to investigate the connection between memory effects and correlated electron dynamics in strong and weak fields. To this end one-dimensional two-electron singlet systems are studied. At the same time these systems include the onedimensional helium atom model, which is an established system to investigate the crucial effects of correlated electron dynamics in external fields. The studies presented in this thesis show that memory effects are negligible for typical strong field processes. Here the approximation of the spatial nonlocality is of primary importance. For the photoabsorption spectra on the other hand the neglect of memory effects leads to qualitative and quantitative errors, which are shown to be connected to transitions of double excitation character. To develop a better understanding of the conditions under which memory effects become important quantum fluid dynamics has been found to be especially suitable. It represents a further exact reformulation of the quantum mechanic many-body problem which is based on hydrodynamic quantities such as density and velocity. Memory effects are shown to be important whenever the velocity field develops strong gradients and dissipative effects contribute. (orig.)
Correlated electron dynamics and memory in time-dependent density functional theory
Energy Technology Data Exchange (ETDEWEB)
Thiele, Mark
2009-07-28
Time-dependent density functional theory (TDDFT) is an exact reformulation of the time-dependent many-electron Schroedinger equation, where the problem of many interacting electrons is mapped onto the Kohn-Sham system of noninteracting particles which reproduces the exact electronic density. In the Kohn-Sham system all non-classical many-body effects are incorporated in the exchange-correlation potential which is in general unknown and needs to be approximated. It is the goal of this thesis to investigate the connection between memory effects and correlated electron dynamics in strong and weak fields. To this end one-dimensional two-electron singlet systems are studied. At the same time these systems include the onedimensional helium atom model, which is an established system to investigate the crucial effects of correlated electron dynamics in external fields. The studies presented in this thesis show that memory effects are negligible for typical strong field processes. Here the approximation of the spatial nonlocality is of primary importance. For the photoabsorption spectra on the other hand the neglect of memory effects leads to qualitative and quantitative errors, which are shown to be connected to transitions of double excitation character. To develop a better understanding of the conditions under which memory effects become important quantum fluid dynamics has been found to be especially suitable. It represents a further exact reformulation of the quantum mechanic many-body problem which is based on hydrodynamic quantities such as density and velocity. Memory effects are shown to be important whenever the velocity field develops strong gradients and dissipative effects contribute. (orig.)
Farzanehpour, Mehdi; Tokatly, Ilya; Nano-Bio Spectroscopy Group; ETSF Scientific Development Centre Team
2015-03-01
We present a rigorous formulation of the time-dependent density functional theory for interacting lattice electrons strongly coupled to cavity photons. We start with an example of one particle on a Hubbard dimer coupled to a single photonic mode, which is equivalent to the single mode spin-boson model or the quantum Rabi model. For this system we prove that the electron-photon wave function is a unique functional of the electronic density and the expectation value of the photonic coordinate, provided the initial state and the density satisfy a set of well defined conditions. Then we generalize the formalism to many interacting electrons on a lattice coupled to multiple photonic modes and prove the general mapping theorem. We also show that for a system evolving from the ground state of a lattice Hamiltonian any density with a continuous second time derivative is locally v-representable. Spanish Ministry of Economy and Competitiveness (Grant No. FIS2013-46159-C3-1-P), Grupos Consolidados UPV/EHU del Gobierno Vasco (Grant No. IT578-13), COST Actions CM1204 (XLIC) and MP1306 (EUSpec).
Spin-wave excitations and electron-magnon scattering from many-body perturbation theory
Friedrich, Christoph; Müller, Mathias C. T. D.; Blügel, Stefan
We study the spin excitations and the electron-magnon scattering in bulk Fe, Co, and Ni within the framework of many-body perturbation theory as implemented in the full-potential linearized augmented-plane-wave method. Starting from the GW approximation we obtain a Bethe-Salpeter equation for the magnetic susceptibility treating single-particle Stoner excitations and magnons on the same footing. Due to approximations used in the numerical scheme, the acoustic magnon dispersion exhibits a small but finite gap at Γ. We analyze this violation of the Goldstone theorem and present an approach that implements the magnetic susceptibility using a renormalized Green function instead of the non-interacting one, leading to a substantial improvement of the Goldstone-mode condition. Finally, we employ the solution of the Bethe-Salpeter equation to construct a self-energy that describes the scattering of electrons and magnons. The resulting renormalized band structures exhibit strong lifetime effects close to the Fermi energy. We also see kinks in the electronic bands, which we attribute to electron scattering with spatially extended spin waves.
Electronic transport properties of one dimensional lithium nanowire using density functional theory
Energy Technology Data Exchange (ETDEWEB)
Thakur, Anil, E-mail: anil-t2001@yahoo.com [Department of Physics, Govt. P.G. College Solan, Himachal Pradesh, India 173212 (India); Kumar, Arun [Department of Physics, Govt. P.G. College Banjar, Himachal Pradesh (India); Chandel, Surjeet [Department of Physics, Govt. P.G. College Bilaspur, Himachal Pradesh (India); Ahluwalia, P. K. [Department of Physics, Himachal Pradesh University Shimla, Himachal Pradesh, India 171005 (India)
2015-05-15
Single nanowire electrode devices are a unique platform for studying as energy storage devices. Lithium nanowire is of much importance in lithium ion batteries and therefore has received a great deal of attention in past few years. In this paper we investigated structural and electronic transport properties of Li nanowire using density functional theory (DFT) with SIESTA code. Electronic transport properties of Li nanowire are investigated theoretically. The calculations are performed in two steps: first an optimized geometry for Li nanowire is obtained using DFT calculations, and then the transport relations are obtained using NEGF approach. SIESTA and TranSIESTA simulation codes are used in the calculations correspondingly. The electrodes are chosen to be the same as the central region where transport is studied, eliminating current quantization effects due to contacts and focusing the electronic transport study to the intrinsic structure of the material. By varying chemical potential in the electrode regions, an I-V curve is traced which is in agreement with the predicted behavior. Agreement of bulk properties of Li with experimental values make the study of electronic and transport properties in lithium nanowires interesting because they are promising candidates as bridging pieces in nanoelectronics. Transmission coefficient and V-I characteristic of Li nano wire indicates that Li nanowire can be used as an electrode device.
Hydrated electron yields in liquid and supercritical water—a theory
Schiller, Robert; Horváth, Ákos
2012-09-01
Our theory, outlined earlier [Schiller, R., 1990. Ion-electron pairs in condensed polar media treated as H-like atoms. J. Chem. Phys. 92, 5527-5532.], is based on the idea that the electron and its geminate positive ion form a hydrogen-like atom, which can be ionized at the expense of the energy fluctuations in the medium. Temperature, T, static relative permittivity, ɛs, and constant-volume molar specific heat, Cvm, play here the decisive role; the combination Tɛs2√{Cvm}, is the variable by which the yield can be predicted. The calculations agree with the recent experimental results on the temperature dependent yields of hydrated electrons by Kratz et al. [Kratz, S., Torres-Alcan, J., Urbanek, J., Lindner, J., Vöhringer, P., 2010. Geminate recombination of hydrated electrons in liquid-to-supercritical water studied by ultrafast time-resolved spectroscopy. Phys. Chem. Chem. Phys. 12, 12169-12176.] reasonably well.
On-Ball Doping of Fullerenes : The Electronic Structure of C59N Dimers from Experiment and Theory
Pichler, Thomas; Knupfer, Martin; Golden, Mark S.; Haffner, Stefan; Friedlein, Rainer; Fink, Jörg; Andreoni, Wanda; Curioni, Alessandro; Keshavarz-K, Majid; Bellavia-Lund, Cheryl; Sastre, Angela; Hummelen, Jan-Cornelis; Wudl, Fred
1997-01-01
We present the first studies of the electronic structure of the heterofullerene (C59N)2 using electron energy-loss spectroscopy in transmission, photoemission spectroscopy, and density functional theory calculations. Both the C 1s excitation spectra and valence band photoemission show negligible
Merli, Marcello; Pavese, Alessandro
2018-03-01
The critical points analysis of electron density, i.e. ρ(x), from ab initio calculations is used in combination with the catastrophe theory to show a correlation between ρ(x) topology and the appearance of instability that may lead to transformations of crystal structures, as a function of pressure/temperature. In particular, this study focuses on the evolution of coalescing non-degenerate critical points, i.e. such that ∇ρ(x c ) = 0 and λ 1 , λ 2 , λ 3 ≠ 0 [λ being the eigenvalues of the Hessian of ρ(x) at x c ], towards degenerate critical points, i.e. ∇ρ(x c ) = 0 and at least one λ equal to zero. The catastrophe theory formalism provides a mathematical tool to model ρ(x) in the neighbourhood of x c and allows one to rationalize the occurrence of instability in terms of electron-density topology and Gibbs energy. The phase/state transitions that TiO 2 (rutile structure), MgO (periclase structure) and Al 2 O 3 (corundum structure) undergo because of pressure and/or temperature are here discussed. An agreement of 3-5% is observed between the theoretical model and experimental pressure/temperature of transformation.
Dynamic scattering theory for dark-field electron holography of 3D strain fields
International Nuclear Information System (INIS)
Lubk, Axel; Javon, Elsa; Cherkashin, Nikolay; Reboh, Shay; Gatel, Christophe; Hÿtch, Martin
2014-01-01
Dark-field electron holography maps strain in crystal lattices into reconstructed phases over large fields of view. Here we investigate the details of the lattice strain–reconstructed phase relationship by applying dynamic scattering theory both analytically and numerically. We develop efficient analytic linear projection rules for 3D strain fields, facilitating a straight-forward calculation of reconstructed phases from 3D strained materials. They are used in the following to quantify the influence of various experimental parameters like strain magnitude, specimen thickness, excitation error and surface relaxation. - Author-Highlights: • We derive a simple dynamic scattering formalism for dark field electron holography based on a perturbative two-beam theory. • The formalism facilitates the projection of 3D strain fields by a simple weighting integral. • The weighted projection depends analytically on the diffraction order, the excitation error and the specimen thickness. • The weighting integral formalism represents an important prerequisite towards the development of tomographic strain reconstruction techniques
DEFF Research Database (Denmark)
Miyagi, Haruhide; Madsen, Lars Bojer
2013-01-01
We present the time-dependent restricted-active-space self-consistent-field (TD-RASSCF) theory as a framework for the time-dependent many-electron problem. The theory generalizes the multiconfigurational time-dependent Hartree-Fock (MCTDHF) theory by incorporating the restricted-active-space scheme...... well known in time-independent quantum chemistry. Optimization of the orbitals as well as the expansion coefficients at each time step makes it possible to construct the wave function accurately while using only a relatively small number of electronic configurations. In numerical calculations of high...
Marek, A; Blum, V; Johanni, R; Havu, V; Lang, B; Auckenthaler, T; Heinecke, A; Bungartz, H-J; Lederer, H
2014-05-28
Obtaining the eigenvalues and eigenvectors of large matrices is a key problem in electronic structure theory and many other areas of computational science. The computational effort formally scales as O(N(3)) with the size of the investigated problem, N (e.g. the electron count in electronic structure theory), and thus often defines the system size limit that practical calculations cannot overcome. In many cases, more than just a small fraction of the possible eigenvalue/eigenvector pairs is needed, so that iterative solution strategies that focus only on a few eigenvalues become ineffective. Likewise, it is not always desirable or practical to circumvent the eigenvalue solution entirely. We here review some current developments regarding dense eigenvalue solvers and then focus on the Eigenvalue soLvers for Petascale Applications (ELPA) library, which facilitates the efficient algebraic solution of symmetric and Hermitian eigenvalue problems for dense matrices that have real-valued and complex-valued matrix entries, respectively, on parallel computer platforms. ELPA addresses standard as well as generalized eigenvalue problems, relying on the well documented matrix layout of the Scalable Linear Algebra PACKage (ScaLAPACK) library but replacing all actual parallel solution steps with subroutines of its own. For these steps, ELPA significantly outperforms the corresponding ScaLAPACK routines and proprietary libraries that implement the ScaLAPACK interface (e.g. Intel's MKL). The most time-critical step is the reduction of the matrix to tridiagonal form and the corresponding backtransformation of the eigenvectors. ELPA offers both a one-step tridiagonalization (successive Householder transformations) and a two-step transformation that is more efficient especially towards larger matrices and larger numbers of CPU cores. ELPA is based on the MPI standard, with an early hybrid MPI-OpenMPI implementation available as well. Scalability beyond 10,000 CPU cores for problem
International Nuclear Information System (INIS)
Krishan, S.
2007-01-01
The Stieltjes transform has been used in place of a more common Laplace transform to determine the time evolution of the self-consistent field (SCF) of an unmagnetized semi-infinite plasma, where the plasma electrons together with a primary and a low-density secondary electron beam move perpendicular to the boundary surface. The secondary beam is produced when the primary beam strikes the grid. Such a plasma system has been investigated by Griskey and Stanzel [M. C. Grisky and R. L. Stenzel, Phys. Rev. Lett. 82, 556 (1999)]. The physical phenomenon, observed in their experiment, has been named by them as ''secondary beam instability.'' The character of the instability observed in the experiment is not the same as predicted by the conventional treatments--the field amplitude does not grow with time. In the frequency spectrum, the theory predicts peak values in the amplitude of SCF at the plasma frequency of plasma and secondary beam electrons, decreasing above and below it. The Stieltjes transform for functions, growing exponentially in the long time limit, does not exist, while the Laplace transform technique gives only exponentially growing solutions. Therefore, it should be interesting to know the kind of solutions that an otherwise physically unstable plasma will yield. In the high-frequency limit, the plasma has been found to respond to any arbitrary frequency of the initial field differentiated only by the strength of the resulting SCF. The condition required for exponential growth in the conventional treatments, and the condition for maximum amplitude (with respect to frequency) in the present treatment, have been found to be the same. Nonlinear mode coupling between the modes excited by the plasma electrons and the low-density secondary beam gives rise to two frequency-dependent peaks in the field amplitude, symmetrically located about the much stronger peak due to the plasma electrons, as predicted by the experiment
Ab initio theory of the electronic structure of nf-ions in solids and liquids
International Nuclear Information System (INIS)
Kulagin, N.
1998-01-01
Full text: In the books and papers we developed the self-consistent field theory of nl- ions in Me+n:[L]k- clusters, where k is number of ligands - L, by ion-ligands distance - R. The results which were obtained for all RE and AC ions for Me+n:[L]k, where L - F - , O -2 and so on ligands, are closely corresponded to experimental data. The expression for energy of the cluster may be write as: E = E 0 + kE 1 + k'(E z + E c + E e + E ex ), (Eq.1), where E 0 and E 1 are the energies of the free nl-ion and surrounding one; E z , E c and E e are the energy of electrons interaction with 'strange' nucleus, Coulomb electron-electron interaction and exchange one. E ex is the energy of the interaction of electrons and nucleus with external field. The equations for the radial one-electron wave functions of the ions in the cluster were obtained by minimizing the Eq. 1 for the radial orbitals of the central ion and ligand one. We have received the general system of equations of the self-consistent field for cluster in liquids and solid states. The results of calculations of the energy structure of clusters and values of the standard radial integrals (spectroscopy parameters) for Ac-ions in 1-2-3 superconductors and RE-ions in garnet crystals by different values of R are qualitatively and quantitatively correct. We've got the best results for pressure dependence of Nd ions spectra, change of optical and X-Ray spectra after irradiation of garnets. We explained the nature of anomalous in SrTiO 3 and separate lasers crystals by used of results of the calculations. In the framework of our approach we obtained the best accuracy for the energy of X- Ray lines for all nf- ions in solids and liquids
International Nuclear Information System (INIS)
Gormezano, C.; Hess, W.; Ichtchenko, G.
1980-07-01
The already obtained data on the Wega Tokamak by lower hybrid heating (f=500 MHz - Psub(HF)=130 KW) are revisited in the light of recent theories on ion stochastic heating and quasi-linear electron Landau damping. It is possible to correctly estimate with these theories the fast ion mean energy, the H.F. power density coupled to the ions and that coupled to the electrons. The values of the parallel index of refraction, Nsub(//), which are necessary to obtain a good quantitative agreement between experiment and theoretical estimates, are the same for the ions and for the electrons, even though at higher values than expected
The effective field theory of dark matter direct detection
Energy Technology Data Exchange (ETDEWEB)
Fitzpatrick, A. Liam; Haxton, Wick; Katz, Emanuel; Lubbers, Nicholas; Xu, Yiming
2013-02-01
We extend and explore the general non-relativistic effective theory of dark matter (DM) direct detection. We describe the basic non-relativistic building blocks of operators and discuss their symmetry properties, writing down all Galilean-invariant operators up to quadratic order in momentum transfer arising from exchange of particles of spin 1 or less. Any DM particle theory can be translated into the coefficients of an effective operator and any effective operator can be simply related to most general description of the nuclear response. We find several operators which lead to novel nuclear responses. These responses differ significantly from the standard minimal WIMP cases in their relative coupling strengths to various elements, changing how the results from different experiments should be compared against each other. Response functions are evaluated for common DM targets — F, Na, Ge, I, and Xe — using standard shell model techniques. We point out that each of the nuclear responses is familiar from past studies of semi-leptonic electroweak interactions, and thus potentially testable in weak interaction studies. We provide tables of the full set of required matrix elements at finite momentum transfer for a range of common elements, making a careful and fully model-independent analysis possible. Finally, we discuss embedding non-relativistic effective theory operators into UV models of dark matter.
Kansara, Shivam; Gupta, Sanjeev K.; Sonvane, Yogesh; Nekrasov, Kirill A.; Kichigina, Natalia V.
2018-02-01
The structural, electronic, and vibrational properties of bulk platinum oxide (PtO) at compressive pressures in the interval from 0 GPa to 35 GPa are investigated using the density functional theory. The calculated electronic band structure of PtO shows poor metallicity at very low density of states on the Fermi level. However, the hybrid pseudopotential calculation yielded 0.78 eV and 1.30 eV direct band and indirect gap, respectively. Importantly, our results predict that PtO has a direct band gap within the framework of HSE06, and it prefers equally zero magnetic order at different pressures. In the Raman spectra, peaks are slightly shifted towards higher frequency with the decrease in pressure. We have also calculated the thermoelectric properties, namely the electronic thermal conductivity and electrical conductivity, with respect to temperature and thermodynamic properties such as entropy, specific heat at constant volume, enthalpy and Gibbs free energy with respect to pressure. The result shows that PtO is a promising candidate for use as a catalyst, in sensors, as a photo-cathode in water electrolysis, for thermal decomposition of inorganic salt and fuel cells.
Density-functional theory based on the electron distribution on the energy coordinate
Takahashi, Hideaki
2018-03-01
We developed an electronic density functional theory utilizing a novel electron distribution n(ɛ) as a basic variable to compute ground state energy of a system. n(ɛ) is obtained by projecting the electron density n({\\boldsymbol{r}}) defined on the space coordinate {\\boldsymbol{r}} onto the energy coordinate ɛ specified with the external potential {\\upsilon }ext}({\\boldsymbol{r}}) of interest. It was demonstrated that the Kohn–Sham equation can also be formulated with the exchange-correlation functional E xc[n(ɛ)] that employs the density n(ɛ) as an argument. It turned out an exchange functional proposed in our preliminary development suffices to describe properly the potential energies of several types of chemical bonds with comparable accuracies to the corresponding functional based on local density approximation. As a remarkable feature of the distribution n(ɛ) it inherently involves the spatially non-local information of the exchange hole at the bond dissociation limit in contrast to conventional approximate functionals. By taking advantage of this property we also developed a prototype of the static correlation functional E sc including no empirical parameters, which showed marked improvements in describing the dissociations of covalent bonds in {{{H}}}2,{{{C}}}2{{{H}}}4 and {CH}}4 molecules.
Electronic structure theory based study of proline interacting with gold nano clusters.
Rai, Sandhya; Singh, Harjinder
2013-10-01
Interaction between metal nanoparticles and biomolecules is important from the view point of developing and designing biosensors. Studies on proline tagged with gold nanoclusters are reported here using density functional theory (DFT) calculations for its structural, electronic and bonding properties. Geometries of the complexes are optimized using the PBE1PBE functional and mixed basis set, i. e., 6-311++G for the amino acid and SDD for the gold clusters. Equilibrium configurations are analyzed in terms of interaction energies, molecular orbitals and charge density. The complexes associated with cluster composed of an odd number of Au atoms show higher stability. Marked decrease in the HOMO-LUMO gaps is observed on complexation. Major components of interaction between the two moieties are: the anchoring N-Au and O-Au bond; and the non covalent interactions between Au and N-H or O-H bonds. The electron affinities and vertical ionization potentials for all complexes are calculated. They show an increased value of electron affinity and ionization potential on complexation. Natural bond orbital (NBO) analysis reveals a charge transfer between the donor (proline) and acceptor (gold cluster). The results indicate that the nature of interaction between the two moieties is partially covalent. Our results will be useful for further experimental studies and may be important for future applications.
Teale, Andrew M.; de Proft, Frank; Tozer, David J.
2008-07-01
Orbital energies in Kohn-Sham density functional theory (DFT) are investigated, paying attention to the role of the integer discontinuity in the exact exchange-correlation potential. A series of closed-shell molecules are considered, comprising some that vertically bind an excess electron and others that do not. High-level ab initio electron densities are used to calculate accurate orbital energy differences, Δɛ, between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO), using the same potential for both. They are combined with accurate vertical ionization potentials, I0, and electron affinities, A0, to determine accurate ``average'' orbital energies. These are the orbital energies associated with an exchange-correlation potential that averages over a constant jump in the accurate potential, of magnitude ΔXC=(I0-A0)-Δɛ, as given by the discontinuity analysis. Local functional HOMO energies are shown to be almost an order of magnitude closer to these average values than to -I0, with typical discrepancies of just 0.02 a.u. For systems that do not bind an excess electron, this level of agreement is only achieved when A0 is set equal to the negative experimental affinity from electron transmission spectroscopy (ETS); it degrades notably when the zero ground state affinity is instead used. Analogous observations are made for the local functional LUMO energies, although the need to use the ETS affinities is less pronounced for systems where the ETS values are very negative. The application of an asymptotic correction recovers the preference, leading to positive LUMO energies (but bound orbitals) for these systems, consistent with the behavior of the average energies. The asymptotically corrected LUMO energies typically agree with the average values to within 0.02 a.u., comparable to that observed with the HOMOs. The study provides numerical support for the view that local functionals exhibit a near-average behavior
Directory of Open Access Journals (Sweden)
Roman F. Nalewajski
2002-04-01
Full Text Available Abstract: Recent studies on applications of the information theoretic concepts to molecular systems are reviewed. This survey covers the information theory basis of the Hirshfeld partitioning of molecular electron densities, its generalization to many electron probabilities, the local information distance analysis of molecular charge distributions, the charge transfer descriptors of the donor-acceptor reactive systems, the elements of a Ã¢Â€ÂœthermodynamicÃ¢Â€Â description of molecular charge displacements, both Ã¢Â€ÂœverticalÃ¢Â€Â (between molecular fragments for the fixed overall density and Ã¢Â€ÂœhorizontalÃ¢Â€Â (involving different molecular densities, with the entropic representation description provided by the information theory. The average uncertainty measures of bond multiplicities in molecular Ã¢Â€ÂœcommunicationÃ¢Â€Â systems are also briefly summarized. After an overview of alternative indicators of the information distance (entropy deficiency, missing information between probability distributions the properties of the Ã¢Â€ÂœstockholderÃ¢Â€Â densities, which minimize the entropy deficiency relative to the promolecule reference, are summarized. In particular, the surprisal analysis of molecular densities is advocated as an attractive information-theoretic tool in the electronic structure theory, supplementary to the familiar density difference diagrams. The subsystem information density equalization rules satisfied by the Hirshfeld molecular fragments are emphasized: the local values of alternative information distance densities of subsystems are equal to the corresponding global value, characterizing the molecule as a whole. These local measures of the information content are semi-quantitatively related to the molecular density difference function. In the density functional theory the effective external potentials of molecular fragments are defined, for which
Directory of Open Access Journals (Sweden)
Dregan Alex
2011-12-01
Full Text Available Abstract Background Electronic patient records are generally coded using extensive sets of codes but the significance of the utilisation of individual codes may be unclear. Item response theory (IRT models are used to characterise the psychometric properties of items included in tests and questionnaires. This study asked whether the properties of medical codes in electronic patient records may be characterised through the application of item response theory models. Methods Data were provided by a cohort of 47,845 participants from 414 family practices in the UK General Practice Research Database (GPRD with a first stroke between 1997 and 2006. Each eligible stroke code, out of a set of 202 OXMIS and Read codes, was coded as either recorded or not recorded for each participant. A two parameter IRT model was fitted using marginal maximum likelihood estimation. Estimated parameters from the model were considered to characterise each code with respect to the latent trait of stroke diagnosis. The location parameter is referred to as a calibration parameter, while the slope parameter is referred to as a discrimination parameter. Results There were 79,874 stroke code occurrences available for analysis. Utilisation of codes varied between family practices with intraclass correlation coefficients of up to 0.25 for the most frequently used codes. IRT analyses were restricted to 110 Read codes. Calibration and discrimination parameters were estimated for 77 (70% codes that were endorsed for 1,942 stroke patients. Parameters were not estimated for the remaining more frequently used codes. Discrimination parameter values ranged from 0.67 to 2.78, while calibration parameters values ranged from 4.47 to 11.58. The two parameter model gave a better fit to the data than either the one- or three-parameter models. However, high chi-square values for about a fifth of the stroke codes were suggestive of poor item fit. Conclusion The application of item response
Low-energy effective Hamiltonians for correlated electron systems beyond density functional theory
Hirayama, Motoaki; Miyake, Takashi; Imada, Masatoshi; Biermann, Silke
2017-08-01
We propose a refined scheme of deriving an effective low-energy Hamiltonian for materials with strong electronic Coulomb correlations beyond density functional theory (DFT). By tracing out the electronic states away from the target degrees of freedom in a controlled way by a perturbative scheme, we construct an effective Hamiltonian for a restricted low-energy target space incorporating the effects of high-energy degrees of freedom in an effective manner. The resulting effective Hamiltonian can afterwards be solved by accurate many-body solvers. We improve this "multiscale ab initio scheme for correlated electrons" (MACE) primarily in two directions by elaborating and combining two frameworks developed by Hirayama et al. [M. Hirayama, T. Miyake, and M. Imada, Phys. Rev. B 87, 195144 (2013), 10.1103/PhysRevB.87.195144] and Casula et al. [M. Casula, P. Werner, L. Vaugier, F. Aryasetiawan, T. Miyake, A. J. Millis, and S. Biermann, Phys. Rev. Lett. 109, 126408 (2012), 10.1103/PhysRevLett.109.126408]: (1) Double counting of electronic correlations between the DFT and the low-energy solver is avoided by using the constrained G W scheme; and (2) the frequency dependent interactions emerging from the partial trace summation are successfully separated into a nonlocal part that is treated following ideas by Hirayama et al. and a local part treated nonperturbatively in the spirit of Casula et al. and are incorporated into the renormalization of the low-energy dispersion. The scheme is favorably tested on the example of SrVO3.
Lagrangian formulation of a consistent relativistic guiding center theory
International Nuclear Information System (INIS)
Wimmel, H.K.
1983-02-01
A new relativistic guiding center mechanics is presented that conserves energy (in time-independent fields) and satisfies a Liouville's theorem. The theory reduces to Littlejohn's theory in the non-relativistic limit and agrees to leading orders in epsilon identical rsub(g)/L with the relativistic theory by Morozov and Solov'ev (which generally lacks a Liouville's theorem). The new theory is developed from an appropriate Lagrangian and is supplemented by a collisionless relativistic kinetic equation for the guiding centers. Moment equations for guiding center density and energy density are also derived. (orig.)
Brown, David M L; Cho, Herman; de Jong, Wibe A
2016-01-01
The testing of theoretical models with experimental data is an integral part of the scientific method, and a logical place to search for new ways of stimulating scientific productivity. Often experiment/theory comparisons may be viewed as a workflow comprised of well-defined, rote operations distributed over several distinct computers, as exemplified by the way in which predictions from electronic structure theories are evaluated with results from spectroscopic experiments. For workflows such as this, which may be laborious and time consuming to perform manually, software that could orchestrate the operations and transfer results between computers in a seamless and automated fashion would offer major efficiency gains. Such tools also promise to alter how researchers interact with data outside their field of specialization by, e.g., making raw experimental results more accessible to theorists, and the outputs of theoretical calculations more readily comprehended by experimentalists. An implementation of an automated workflow has been developed for the integrated analysis of data from nuclear magnetic resonance (NMR) experiments and electronic structure calculations. Kepler (Altintas et al. 2004) open source software was used to coordinate the processing and transfer of data at each step of the workflow. This workflow incorporated several open source software components, including electronic structure code to compute NMR parameters, a program to simulate NMR signals, NMR data processing programs, and others. The Kepler software was found to be sufficiently flexible to address several minor implementation challenges without recourse to other software solutions. The automated workflow was demonstrated with data from a [Formula: see text] NMR study of uranyl salts described previously (Cho et al. in J Chem Phys 132:084501, 2010). The functional implementation of an automated process linking NMR data with electronic structure predictions demonstrates that modern software
ES12; The 24th Annual Workshop on Recent Developments in Electronic Structure Theory
Energy Technology Data Exchange (ETDEWEB)
Holzwarth, Natalie [Wake Forest Univ., Winston-Salem, NC (United States); Thonhauser, Timo [Wake Forest Univ., Winston-Salem, NC (United States); Salam, Akbar [Wake Forest Univ., Winston-Salem, NC (United States)
2012-06-29
ES12: The 24th Annual Workshop on Recent Developments in Electronic Structure Theory was held June 5-8, 2012 at Wake Forest University in Winston-Salem, NC 27109. The program consisted of 24 oral presentations, 70 posters, and 2 panel discussions. The attendance of the Workshop was comparable to or larger than previous workshops and participation was impressively diverse. The 136 participants came from all over the world and included undergraduate students, graduate students, postdoctoral researchers, and senior scientists. The general assessment of the Workshop was extremely positive in terms of the high level of scientific presentations and discussions, and in terms of the schedule, accommodations, and affordability of the meeting.
Electronic and Optical Properties of Sodium Niobate: A Density Functional Theory Study
Directory of Open Access Journals (Sweden)
Daniel Fritsch
2018-01-01
Full Text Available In recent years, much effort has been devoted to replace the most commonly used piezoelectric ceramic lead zirconate titanate Pb[ZrxTi1−x]O3 (PZT with a suitable lead-free alternative for memory or piezoelectric applications. One possible alternative to PZT is sodium niobate as it exhibits electrical and mechanical properties that make it an interesting material for technological applications. The high-temperature simple cubic perovskite structure undergoes a series of structural phase transitions with decreasing temperature. However, particularly the phases at room temperature and below are not yet fully characterised and understood. Here, we perform density functional theory calculations for the possible phases at room temperature and below and report on the structural, electronic, and optical properties of the different phases in comparison to experimental findings.
International Nuclear Information System (INIS)
Moradian, Rostam; Behzad, Somayeh; Chegel, Raad
2008-01-01
By using ab initio density functional theory the structural and electronic properties of isolated and bundled (8,0) and (6,6) silicon carbide nanotubes (SiCNTs) are investigated. Our results show that for such small diameter nanotubes the inter-tube interaction causes a very small radial deformation, while band splitting and reduction of the semiconducting energy band gap are significant. We compared the equilibrium interaction energy and inter-tube separation distance of (8,0) SiCNT bundle with (10,0) carbon nanotube (CNT) bundle where they have the same radius. We found that there is a larger inter-tube separation and weaker inter-tube interaction in the (8,0) SiCNT bundle with respect to (10,0) CNT bundle, although they have the same radius
Shityakov, Sergey; Roewer, Norbert; Förster, Carola; Broscheit, Jens-Albert
2017-07-01
The purpose of this study was to develop and implement an in silico model of indigoid-based single-electron transistor (SET) nanodevices, which consist of indigoid molecules from natural dye weakly coupled to gold electrodes that function in a Coulomb blockade regime. The electronic properties of the indigoid molecules were investigated using the optimized density-functional theory (DFT) with a continuum model. Higher electron transport characteristics were determined for Tyrian purple, consistent with experimentally derived data. Overall, these results can be used to correctly predict and emphasize the electron transport functions of organic SETs, demonstrating their potential for sustainable nanoelectronics comprising the biodegradable and biocompatible materials.
Quantum hydrodynamic theory for plasmonics: Impact of the electron density tail
Ciracı, Cristian; Della Sala, Fabio
2016-05-01
Multiscale plasmonic systems (e.g., extended metallic nanostructures with subnanometer inter-distances) play a key role in the development of next-generation nanophotonic devices. An accurate modeling of the optical interactions in these systems requires an accurate description of both quantum effects and far-field properties. Classical electromagnetism can only describe the latter, while time-dependent density functional theory (TD-DFT) can provide a full first-principles quantum treatment. However, TD-DFT becomes computationally prohibitive for sizes that exceed few nanometers, which are instead very important for most applications. In this article, we introduce a method based on the quantum hydrodynamic theory (QHT) that includes nonlocal contributions of the kinetic energy and the correct asymptotic description of the electron density. We show that our QHT method can predict both plasmon energy and spill-out effects in metal nanoparticles in excellent agreement with TD-DFT predictions, thus allowing reliable and efficient calculations of both quantum and far-field properties in multiscale plasmonic systems.
Harkless, J. A. W.; Rodriguez, J. H.; Mitas, L.; Lester, W. A.
2003-03-01
Single point calculations of the ground state electronic structure of peroxynitrite anion have been performed at the optimized cis geometry using the restricted Hartree-Fock (RHF), Møller Plesset second order perturbation theory (MP2), generalized gradient approximation density functional theory (GGA DFT) in the B3LYP form and two quantum Monte Carlo (QMC) methods, variational Monte Carlo (VMC) and diffusion Monte Carlo (DMC). These calculations reveal differences in atomization energies estimated by B3LYP (287.03 kcal/mol), MP2 (290.84 kcal/mol), and DMC, 307.4(1.9) kcal/mol, as compared to experiment, 313(1) kcal/mol. The error associated with MP2 and B3LYP methods is attributed largely to differential recovery of correlation energies for neutral nitrogen and oxygen atoms relative to the oxygen and peroxynitrite anions. In addition, basis set studies were carried out to determine potential sources of error in MP2 and B3LYP valence energy values. Our studies indicate that MP2 and B3LYP valence energies are strongly dependent on the presence of diffuse functions for the negative ions O- and ONOO-.
International Nuclear Information System (INIS)
Tachikawa, Hiroto; Iyama, Tetsuji
2014-01-01
Electronic structures and band gaps of hydrogenated fullerenes have been investigated by means of density functional theory method. The mechanism of hydrogen addition reaction to the fullerene (C 60 ) surface was also investigated. Addition of one and two hydrogen atoms was examined in the calculations. The binding energies of the second hydrogen atom to C 60 H were widely distributed in the range 1.5–3.6 eV. It was found that the bonding energy is strongly dependent on the spin density of carbon atom of C 60 H. The second hydrogen atom preferentially binds to the neighbor site of the first addition site. The electronic states and excitation energies of C 60 -H were discussed on the basis of theoretical results. - Highlights: • Hydrogen atom addition to C60 was investigated. • First hydrogen atom addition proceeded with very low activation barrier. • Second hydrogen addition was dependent on the binding site. • Addition site of second atom was correlated with spin density
Rudberg, Elias
2012-02-01
Self-consistency-based Kohn-Sham density functional theory (KS-DFT) electronic structure calculations with Gaussian basis sets are reported for a set of 17 protein-like molecules with geometries obtained from the Protein Data Bank. It is found that in many cases such calculations do not converge due to vanishing HOMO-LUMO gaps. A sequence of polyproline I helix molecules is also studied and it is found that self-consistency calculations using pure functionals fail to converge for helices longer than six proline units. Since the computed gap is strongly correlated to the fraction of Hartree-Fock exchange, test calculations using both pure and hybrid density functionals are reported. The tested methods include the pure functionals BLYP, PBE and LDA, as well as Hartree-Fock and the hybrid functionals BHandHLYP, B3LYP and PBE0. The effect of including solvent molecules in the calculations is studied, and it is found that the inclusion of explicit solvent molecules around the protein fragment in many cases gives a larger gap, but that convergence problems due to vanishing gaps still occur in calculations with pure functionals. In order to achieve converged results, some modeling of the charge distribution of solvent water molecules outside the electronic structure calculation is needed. Representing solvent water molecules by a simple point charge distribution is found to give non-vanishing HOMO-LUMO gaps for the tested protein-like systems also for pure functionals.
International Nuclear Information System (INIS)
Heilmann, D.B.
2007-02-01
The two-plane HUBBARD model, which is a model for some electronic properties of undoped YBCO superconductors as well as displays a MOTT metal-to-insulator transition and a metal-to-band insulator transition, is studied within Dynamical Mean-Field Theory using HIRSCH-FYE Monte Carlo. In order to find the different transitions and distinguish the types of insulator, we calculate the single-particle spectral densities, the self-energies and the optical conductivities. We conclude that there is a continuous transition from MOTT to band insulator. In the second part, ground state properties of a diagonally disordered HUBBARD model is studied using a generalisation of Path Integral Renormalisation Group, a variational method which can also determine low-lying excitations. In particular, the distribution of antiferromagnetic properties is investigated. We conclude that antiferromagnetism breaks down in a percolation-type transition at a critical disorder, which is not changed appreciably by the inclusion of correlation effects, when compared to earlier studies. Electronic and excitation properties at the system sizes considered turn out to primarily depend on the geometry. (orig.)
International Nuclear Information System (INIS)
White, R D; Robson, R E; Schmidt, B; Morrison, Michael A
2003-01-01
The 'two-term' approximation (representation of the electron distribution by the first two terms of an expansion in spherical harmonics in velocity space) continues to occupy a central role in the low-temperature plasma physics literature, in spite of the mass of evidence illustrating its inadequacy in the swarm (free diffusion) limit for many molecular gases. Part of the problem lies in the failure of many authors to specify quantitatively what they mean when they say that the two-term approximation is 'acceptable'. Thus for example, an error of 10% in transport coefficients may well be acceptable in many plasma applications, but for analysis of highly accurate swarm experiments to compare with ab initio and beam-derived cross-sections, 0.1% or less is required, making 'multi-term' analysis mandatory. While reconciliation of the swarm and plasma literature along the lines of two different accuracy regimes may thus be possible, we dispute claims that the two-term approximation is generally satisfactory for inversion of swarm experiment data to obtain electron impact cross-sections. The unsatisfactory nature of other assumptions implicit in much of the modern plasma kinetic theory literature is also discussed
A density functional theory investigation of the electronic structure and spin moments of magnetite
Noh, Junghyun
2014-08-01
We present the results of density functional theory (DFT) calculations on magnetite, Fe3O4, which has been recently considered as electrode in the emerging field of organic spintronics. Given the nature of the potential applications, we evaluated the magnetite room-temperature cubic phase in terms of structural, electronic, and magnetic properties. We considered GGA (PBE), GGA + U (PBE + U), and range-separated hybrid (HSE06 and HSE(15%)) functionals. Calculations using HSE06 and HSE(15%) functionals underline the impact that inclusion of exact exchange has on the electronic structure. While the modulation of the band gap with exact exchange has been seen in numerous situations, the dramatic change in the valence band nature and states near the Fermi level has major implications for even a qualitative interpretation of the DFT results. We find that HSE06 leads to highly localized states below the Fermi level while HSE(15%) and PBE + U result in delocalized states around the Fermi level. The significant differences in local magnetic moments and atomic charges indicate that describing room-temperature bulk materials, surfaces and interfaces may require different functionals than their low-temperature counterparts.
Schäfer, Sascha; Liang, Wenxi; Zewail, Ahmed H
2011-12-07
Recent studies in ultrafast electron crystallography (UEC) using a reflection diffraction geometry have enabled the investigation of a wide range of phenomena on the femtosecond and picosecond time scales. In all these studies, the analysis of the diffraction patterns and their temporal change after excitation was performed within the kinematical scattering theory. In this contribution, we address the question, to what extent dynamical scattering effects have to be included in order to obtain quantitative information about structural dynamics. We discuss different scattering regimes and provide diffraction maps that describe all essential features of scatterings and observables. The effects are quantified by dynamical scattering simulations and examined by direct comparison to the results of ultrafast electron diffraction experiments on an in situ prepared Ni(100) surface, for which structural dynamics can be well described by a two-temperature model. We also report calculations for graphite surfaces. The theoretical framework provided here allows for further UEC studies of surfaces especially at larger penetration depths and for those of heavy-atom materials. © 2011 American Institute of Physics
Energy Technology Data Exchange (ETDEWEB)
Heilmann, D.B.
2007-02-15
The two-plane HUBBARD model, which is a model for some electronic properties of undoped YBCO superconductors as well as displays a MOTT metal-to-insulator transition and a metal-to-band insulator transition, is studied within Dynamical Mean-Field Theory using HIRSCH-FYE Monte Carlo. In order to find the different transitions and distinguish the types of insulator, we calculate the single-particle spectral densities, the self-energies and the optical conductivities. We conclude that there is a continuous transition from MOTT to band insulator. In the second part, ground state properties of a diagonally disordered HUBBARD model is studied using a generalisation of Path Integral Renormalisation Group, a variational method which can also determine low-lying excitations. In particular, the distribution of antiferromagnetic properties is investigated. We conclude that antiferromagnetism breaks down in a percolation-type transition at a critical disorder, which is not changed appreciably by the inclusion of correlation effects, when compared to earlier studies. Electronic and excitation properties at the system sizes considered turn out to primarily depend on the geometry. (orig.)
International Nuclear Information System (INIS)
Meer, R. van; Gritsenko, O. V.; Baerends, E. J.
2014-01-01
Time dependent density matrix functional theory in its adiabatic linear response formulation delivers exact excitation energies ω α and oscillator strengths f α for two-electron systems if extended to the so-called phase including natural orbital (PINO) theory. The Löwdin-Shull expression for the energy of two-electron systems in terms of the natural orbitals and their phases affords in this case an exact phase-including natural orbital functional (PILS), which is non-primitive (contains other than just J and K integrals). In this paper, the extension of the PILS functional to N-electron systems is investigated. With the example of an elementary primitive NO functional (BBC1) it is shown that current density matrix functional theory ground state functionals, which were designed to produce decent approximations to the total energy, fail to deliver a qualitatively correct structure of the (inverse) response function, due to essential deficiencies in the reconstruction of the two-body reduced density matrix (2RDM). We now deduce essential features of an N-electron functional from a wavefunction Ansatz: The extension of the two-electron Löwdin-Shull wavefunction to the N-electron case informs about the phase information. In this paper, applications of this extended Löwdin-Shull (ELS) functional are considered for the simplest case, ELS(1): one (dissociating) two-electron bond in the field of occupied (including core) orbitals. ELS(1) produces high quality ω α (R) curves along the bond dissociation coordinate R for the molecules LiH, Li 2 , and BH with the two outer valence electrons correlated. All of these results indicate that response properties are much more sensitive to deficiencies in the reconstruction of the 2RDM than the ground state energy, since derivatives of the functional with respect to both the NOs and the occupation numbers need to be accurate
Electron correlation energy in confined two-electron systems
Energy Technology Data Exchange (ETDEWEB)
Wilson, C.L. [Chemistry Program, Centre College, 600 West Walnut Street, Danville, KY 40422 (United States); Montgomery, H.E., E-mail: ed.montgomery@centre.ed [Chemistry Program, Centre College, 600 West Walnut Street, Danville, KY 40422 (United States); Sen, K.D. [School of Chemistry, University of Hyderabad, Hyderabad 500 046 (India); Thompson, D.C. [Chemistry Systems and High Performance Computing, Boehringer Ingelheim Pharamaceuticals Inc., 900 Ridgebury Road, Ridgefield, CT 06877 (United States)
2010-09-27
Radial, angular and total correlation energies are calculated for four two-electron systems with atomic numbers Z=0-3 confined within an impenetrable sphere of radius R. We report accurate results for the non-relativistic, restricted Hartree-Fock and radial limit energies over a range of confinement radii from 0.05-10a{sub 0}. At small R, the correlation energies approach limiting values that are independent of Z while at intermediate R, systems with Z{>=}1 exhibit a characteristic maximum in the correlation energy resulting from an increase in the angular correlation energy which is offset by a decrease in the radial correlation energy.
Numerical perturbative methods in the quantum theory of physical systems
International Nuclear Information System (INIS)
Adam, G.
1980-01-01
During the last two decades, development of digital electronic computers has led to the deployment of new, distinct methods in theoretical physics. These methods, based on the advances of modern numerical analysis as well as on specific equations describing physical processes, enabled to perform precise calculations of high complexity which have completed and sometimes changed our image of many physical phenomena. Our efforts have concentrated on the development of numerical methods with such intrinsic performances as to allow a successful approach of some Key issues in present theoretical physics on smaller computation systems. The basic principle of such methods is to translate, in numerical analysis language, the theory of perturbations which is suited to numerical rather than to analytical computation. This idea has been illustrated by working out two problems which arise from the time independent Schroedinger equation in the non-relativistic approximation, within both quantum systems with a small number of particles and systems with a large number of particles, respectively. In the first case, we are led to the numerical solution of some quadratic ordinary differential equations (first section of the thesis) and in the second case, to the solution of some secular equations in the Brillouin area (second section). (author)
Regeta, Khrystyna; Allan, Michael; Winstead, Carl; McKoy, Vincent; Mašín, Zdeněk; Gorfinkiel, Jimena D
2016-01-14
We measured differential cross sections for elastic (rotationally integrated) electron scattering on pyrimidine, both as a function of angle up to 180(∘) at electron energies of 1, 5, 10, and 20 eV and as a function of electron energy in the range 0.1-14 eV. The experimental results are compared to the results of the fixed-nuclei Schwinger variational and R-matrix theoretical methods, which reproduce satisfactorily the magnitudes and shapes of the experimental cross sections. The emphasis of the present work is on recording detailed excitation functions revealing resonances in the excitation process. Resonant structures are observed at 0.2, 0.7, and 4.35 eV and calculations for different symmetries confirm their assignment as the X̃(2)A2, Ã(2)B1, and B̃(2)B1 shape resonances. As a consequence of superposition of coherent resonant amplitudes with background scattering the B̃(2)B1 shape resonance appears as a peak, a dip, or a step function in the cross sections recorded as a function of energy at different scattering angles and this effect is satisfactorily reproduced by theory. The dip and peak contributions at different scattering angles partially compensate, making the resonance nearly invisible in the integral cross section. Vibrationally integrated cross sections were also measured at 1, 5, 10 and 20 eV and the question of whether the fixed-nuclei cross sections should be compared to vibrationally elastic or vibrationally integrated cross section is discussed.
Gerasimov, S. B.
2017-12-01
Within the non-relativistic approach to photo-absorption sum rules for the 3N(4N)-nuclei the new σ ‑1 sum rules proposed which are based on general charge-symmetry (CS) consequences for a pair of the “CS-conjugated” triton and 3 He nuclei and for the “self-conjugated” nucleus 4 He. The numerical deviations from the less general “charge-independent” approach leading to the long-known Foldy-Khokhlow sum rules are estimated. In the relativistic domain the functional inapplicability is demonstrated of the “charge independence” approximation in the derivation of the σ ‑1 - type sum rules in the case of nucleons. With application of the relevant “charge symmetry” approach, the general system of the sum rules is derived and the inevitable isospin-dependent dynamics of the constituent quarks is underlined.
Directory of Open Access Journals (Sweden)
Hélio Godoy
2007-07-01
Full Text Available This paper addresses Documentary Realism, focusing on thephysical phenomena of transduction that take place in analog and digital audiovisual systems, herein analyzed in the light of the Sampling Theory, within the framework of Shannon and Weaver’s Information Theory. Transduction is a process by which one type of energy is transformed into another, or by which information is transcodiﬁed. Within the scope of Documentary Realism, it cannotbe claimed that electronic audiovisual signs, because of their technical digital features lead to a rupture with reality. Rather, the digital documentary, based on electronic digital cinematography, is still an index of reality.
International Nuclear Information System (INIS)
Talaat, M.E.
1986-01-01
A two electron group model (bulk and tail electrons) is used to devise a theory for predicting current-voltage characteristic curves of RF discharges in helium with flow, which would agree with the experimental results of an 11 MHz RF axial discharge tests with helium flow inside a quartz tube, having an ID of 2.2 cms, at flow velocities up to μ = 485 m/s, (at reduced pressures p/sub o/ from 217 to 362 torrs). The theory assumes that the bulk electrons are Maxwellian, at a temperature T/sub b/, and have kinetic energies (1/2 mv/sup 2/ = eV) between o and eV/sub l/ (V/sub l/ = the helium metastable potential). The electrons of the depressed tail of the distribution function are also Maxwellian, at another temperature T/sub t/, and have eV > eV/sub l/
Minimal gravitational coupling in the Newtonian theory and the covariant Schroedinger equation
International Nuclear Information System (INIS)
Duval, C.; Kuenzle, H.P.
1983-02-01
The role of the Bargmann group (11-dimensional extended Galilei group) in non relativistic gravitation theory is investigated. The generalized Newtonian gravitation theory (Newton-Cartan theory) achieves the status of a gauge theory about as much as General Relativity and couples minimally to a complex scalar field leading to a fourdimensionally covariant Schroedinger equation. Matter current and stress-energy tensor follow correctly from the Lagrangian. This theory on curved Newtonian space-time is also shown to be a limit of the Einstein-Klein-Gordon theory
Low-energy electron scattering from CO. 2: Ab-initio study using the frame-transformation theory
Chandra, N.
1976-01-01
The Wigner-Eisenbud R matrix method has been combined with the frame transformation theory to study electron scattering from molecular systems. The R matrix, calculated at the boundary point of the molecular core radius, has been transformed to the space frame in order to continue the solution of the scattering equations in the outer region where rotational motion of the nuclei is taken into account. This procedure has been applied to a model calculation of thermal energy electron scattering from CO.
International Nuclear Information System (INIS)
Boesten, L.G.J.
1978-01-01
Calculations on the threshold ionization of H, He + and Li 2+ by electrons have been performed to study the so-called 'post-collision interaction' (P.C.I.) effects which appear to affect the threshold ionization process significantly. These effects are caused by the long range Coulomb interactions between the two electrons as they move away from the nucleus. The long range interactions are fully taken into account in the classical three-body collision theory. In quantum mechanical theories, however, it is difficult to account for these interactions. This theory has been used to study the ionization of He + -ions by electron impact up to much higher energies (up till ten times the threshold energy). The results are compared with experimental results of Dolder et al. (1961) and with results of quantum mechanical calculations. Results are given for ionization of helium atoms by electron or proton impact. This collision process, in which four particles are involved, can under certain circumstances be treated as a collision process in which only three particles are involved. Calculations are performed concerning: a) cross sections for ionization of metastable helium atoms by electron impact, b) cross sections for ionization of ground-state helium atoms by fast proton impact (energy and angular distributions of ejected electrons), c) generalized oscillator strengths for ionization of helium by fast proton impact
Czech Academy of Sciences Publication Activity Database
Čársky, Petr
2015-01-01
Roč. 191, č. 2015 (2015), s. 191-192 ISSN 1551-7616 R&D Projects: GA MŠk OC09079; GA MŠk(CZ) OC10046; GA ČR GA202/08/0631 Grant - others:COST(XE) CM0805; COST(XE) CM0601 Institutional support: RVO:61388955 Keywords : electron-scattering * calculation of cross sections * second-order perturbation theory Subject RIV: CF - Physical ; Theoretical Chemistry
Anderson, Lindsey N; Oviedo, M Belén; Wong, Bryan M
2017-04-11
The treatment of atomic anions with Kohn-Sham density functional theory (DFT) has long been controversial because the highest occupied molecular orbital (HOMO) energy, E HOMO , is often calculated to be positive with most approximate density functionals. We assess the accuracy of orbital energies and electron affinities for all three rows of elements in the periodic table (H-Ar) using a variety of theoretical approaches and customized basis sets. Among all of the theoretical methods studied here, we find that a nonempirically tuned range-separated approach (constructed to satisfy DFT-Koopmans' theorem for the anionic electron system) provides the best accuracy for a variety of basis sets, even for small basis sets where most functionals typically fail. Previous approaches to solve this conundrum of positive E HOMO values have utilized non-self-consistent methods; however, electronic properties, such as electronic couplings/gradients (which require a self-consistent potential and energy), become ill-defined with these approaches. In contrast, the nonempirically tuned range-separated procedure used here yields well-defined electronic couplings/gradients and correct E HOMO values because both the potential and resulting electronic energy are computed self-consistently. Orbital energies and electron affinities are further analyzed in the context of the electronic energy as a function of electronic number (including fractional numbers of electrons) to provide a stringent assessment of self-interaction errors for these complex anion systems.
Wuttisela, Karntarat
2017-01-01
There are various types of instructional media related to Valence Shell Electron Pair Repulsion (VSEPR) but there is a lack of diversity of resources devoted to assessment. This research presents an assessment and comparison of students' understanding of VSEPR theory before and after tuition involving the use of the foam molecule model (FMM) and…
Czech Academy of Sciences Publication Activity Database
Kolorenč, Jindřich; Shick, Alexander; Lichtenstein, A.I.
2015-01-01
Roč. 92, č. 8 (2015), "085125-1"-"085125-10" ISSN 1098-0121 R&D Projects: GA ČR GC15-05872J Institutional support: RVO:68378271 Keywords : electronic-structure calculations * dynamical mean-field theory * Mott insulators * actinides * oxides * photoemission Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014
DEFF Research Database (Denmark)
Hedegård, Erik Donovan
2017-01-01
We have in a series of recent papers investigated electronic excited states with a hybrid between a complete active space self-consistent field (CASSCF) wave function and density functional theory (DFT). This method has been dubbed the CAS short-range DFT method (CAS–srDFT). The previous papers...
International Nuclear Information System (INIS)
Brandow, B.H.
1977-01-01
The Brueckner--Goldstone form of linked-cluster perturbation theory is derived, together with its open-shell analog, by an elementary time-independent approach. This serves to focus attention on the physical interpretation of the results. The open-shell expansion is used to provide a straightforward justification for the effective π-electron Hamiltonians of planar organic molecules
Feil, D.; Feil, Dirk
1992-01-01
Quantum chemistry and the concepts used daily in chemistry are increasingly growing apart. Among the concepts that are able to bridge the gap between theory and experimental practice, electron density distribution has an important place. The study of this distribution has led to new developments in
Wiederkehr, Karl Heinrich
2010-01-01
The development of an electron-theory of metals is closely connected with early speculation in the period before Maxwell (W Weber and others) regarding electrical conductivity in metals. These Speculations were in contrast with Faraday's view of an all-embracing molecular dielectric polarisation, and a subsequent passage of charges in metallic conductors. In terms of the empirical law of Wiedemann-Franz-Lorenz, the conductivity of electricity and heat had to be treated commonly. The classical electron-theory of metals (Riecke, Drude, H.A. Lorentz) reached a dead end on account of problems concerned with specific heat capacity. Sommerfeld, by means of the Quantum theory and the Fermi-Statistic, could find the solution.
Tuti, Timothy; Nzinga, Jacinta; Njoroge, Martin; Brown, Benjamin; Peek, Niels; English, Mike; Paton, Chris; van der Veer, Sabine N
2017-05-12
Audit and feedback is a common intervention for supporting clinical behaviour change. Increasingly, health data are available in electronic format. Yet, little is known regarding if and how electronic audit and feedback (e-A&F) improves quality of care in practice. The study aimed to assess the effectiveness of e-A&F interventions in a primary care and hospital context and to identify theoretical mechanisms of behaviour change underlying these interventions. In August 2016, we searched five electronic databases, including MEDLINE and EMBASE via Ovid, and the Cochrane Central Register of Controlled Trials for published randomised controlled trials. We included studies that evaluated e-A&F interventions, defined as a summary of clinical performance delivered through an interactive computer interface to healthcare providers. Data on feedback characteristics, underlying theoretical domains, effect size and risk of bias were extracted by two independent review authors, who determined the domains within the Theoretical Domains Framework (TDF). We performed a meta-analysis of e-A&F effectiveness, and a narrative analysis of the nature and patterns of TDF domains and potential links with the intervention effect. We included seven studies comprising of 81,700 patients being cared for by 329 healthcare professionals/primary care facilities. Given the extremely high heterogeneity of the e-A&F interventions and five studies having a medium or high risk of bias, the average effect was deemed unreliable. Only two studies explicitly used theory to guide intervention design. The most frequent theoretical domains targeted by the e-A&F interventions included 'knowledge', 'social influences', 'goals' and 'behaviour regulation', with each intervention targeting a combination of at least three. None of the interventions addressed the domains 'social/professional role and identity' or 'emotion'. Analyses identified the number of different domains coded in control arm to have the biggest
Huang, Danhong; Iurov, Andrii; Gao, Fei; Gumbs, Godfrey; Cardimona, D. A.
2018-02-01
The effects of point defects on the loss of either energies of ballistic electron beams or incident photons are studied by using a many-body theory in a multi-quantum-well system. This theory includes the defect-induced vertex correction to a bare polarization function of electrons within the ladder approximation, and the intralayer and interlayer screening of defect-electron interactions is also taken into account in the random-phase approximation. The numerical results of defect effects on both energy-loss and optical-absorption spectra are presented and analyzed for various defect densities, numbers of quantum wells, and wave vectors. The diffusion-reaction equation is employed for calculating distributions of point defects in a layered structure. For completeness, the production rate for Frenkel-pair defects and their initial concentration are obtained based on atomic-level molecular-dynamics simulations. By combining the defect-effect, diffusion-reaction, and molecular-dynamics models with an available space-weather-forecast model, it will be possible in the future to enable specific designing for electronic and optoelectronic quantum devices that will be operated in space with radiation-hardening protection and, therefore, effectively extend the lifetime of these satellite onboard electronic and optoelectronic devices. Specifically, this theory can lead to a better characterization of quantum-well photodetectors not only for high quantum efficiency and low dark current density but also for radiation tolerance or mitigating the effects of the radiation.
To the theory of X-ray and electron dynamic scattering in defect-containing crystals
International Nuclear Information System (INIS)
Chukhovskij, F.N.
1982-01-01
The novel approach to the X-ray and electron dynamic scattering theory based on the dynamic equations ''in the dispersion surface representation'' is formulated. The formally exact solution of two-wave diffraction scattering problem is obtained using the scattering matrix, the obvious expression for which is found. The general formulae describing the plane wave diffraction scattering in absorbing crystals in the weak distortion range has been obtained. The formulae allows one to determine the total change sign of the displacement function Δα(x,y)=2πg vectorx(R vector (r vector) 1 -R vector(r vector) 2 ) on the base of the known sign of the mean deflection magnitude in a crystal as a whole from the exact Bragg position (g vector - the inverse lattice vector, R vector - the displacement field vector, t - the crystal thickness, R vector(r vector) 1 =R vector (r) ar z=t, R vector(r vector) 2 =R(r) at z=0). In the quasiclassical approximation the formation of the diffraction image of a dislocation positioned in such a way that the dislocation axis is parallel to the diffraction reflection vector is considered for the incident plane and spherical waves
Electron energy and charge albedos - calorimetric measurement vs Monte Carlo theory
International Nuclear Information System (INIS)
Lockwood, G.J.; Ruggles, L.E.; Miller, G.H.; Halbleib, J.A.
1981-11-01
A new calorimetric method has been employed to obtain saturated electron energy albedos for Be, C, Al, Ti, Mo, Ta, U, and UO 2 over the range of incident energies from 0.1 to 1.0 MeV. The technique was so designed to permit the simultaneous measurement of saturated charge albedos. In the cases of C, Al, Ta, and U the measurements were extended down to about 0.025 MeV. The angle of incidence was varied from 0 0 (normal) to 75 0 in steps of 15 0 , with selected measurements at 82.5 0 in Be and C. In each case, state-of-the-art predictions were obtained from a Monte Carlo model. The generally good agreement between theory and experiment over this extensive parameter space represents a strong validation of both the theoretical model and the new experimental method. Nevertheless, certain discrepancies at low incident energies, especially in high-atomic-number materials, and at all energies in the case of the U energy albedos are not completely understood
The theory and simulation of relativistic electron beam transport in the ion-focused regime
International Nuclear Information System (INIS)
Swanekamp, S.B.; Holloway, J.P.; Kammash, T.; Gilgenbach, R.M.
1992-01-01
Several recent experiments involving relativistic electron beam (REB) transport in plasma channels show two density regimes for efficient transport; a low-density regime known as the ion-focused regime (IFR) and a high-pressure regime. The results obtained in this paper use three separate models to explain the dependency of REB transport efficiency on the plasma density in the IFR. Conditions for efficient beam transport are determined by examining equilibrium solutions of the Vlasov--Maxwell equations under conditions relevant to IFR transport. The dynamic force balance required for efficient IFR transport is studied using the particle-in-cell (PIC) method. These simulations provide new insight into the transient beam front physics as well as the dynamic approach to IFR equilibrium. Nonlinear solutions to the beam envelope are constructed to explain oscillations in the beam envelope observed in the PIC simulations but not contained in the Vlasov equilibrium analysis. A test particle analysis is also developed as a method to visualize equilibrium solutions of the Vlasov equation. This not only provides further insight into the transport mechanism but also illustrates the connections between the three theories used to describe IFR transport. Separately these models provide valuable information about transverse beam confinement; together they provide a clear physical understanding of REB transport in the IFR
Quantum theory of scattering of channeled electrons and positrons in a crystal
International Nuclear Information System (INIS)
Bazylev, V.A.; Goloviznin, V.V.
1982-01-01
The quantum theory of elastic scattering of electrons and positrons on plane or axial channeling in a thin crystal is developed. The role of coherent (without phonon excitation) and incoherent scattering by atoms of the plane (chain) is investigated. It is shown that incoherent scattering which leads to dechanneling cannot be reduced to scattering by an isolated atom. Allowance for ordered arrangement of the atoms in the plane (chain) of the crystal leads to suppression of the motion levels. It is also shown that on movement of a particle along the plane in directions strongly differing from those of the principal axes, the scattering is incoherent and is determined by thermal vibrations of the nuclei. As the direction of the particle momentum approaches those of the principal axes, the role of coherent scattering without recoil by the crystal lattice nuclei increases and may become dicisive. The probability of large- angle scattering increases relatively in this case. Under certain conditions coherent scattering may become resonant [ru
Gonzalez, Carlos A; Squitieri, Emilio; Franco, Hector J; Rincon, Luis C
2017-01-26
The Kohn-Sham density functional theory (DFT) formalism has been used to investigate the influence of the stationary behavior of the electron density (ρ(r⃗;s)) along a minimum energy path on the corresponding stationary conditions observed in the total potential energy of the reactive system, information theory measures (Shannon information entropy and Onicescu information energy), and chemical reactivity indexes (the chemical hardness). The theoretical treatment presented in this work, combined with DFT calculations on 3 different test reactions: Ḣ' + H 2 , Ḣ' + CH 4 and H - + CH 4 , suggest that for any reactive system, properties that can be cast as a functional of the electron density, must exhibit stationary points along the IRC path modulated by the corresponding stationary behavior of the electron density.
Richard, Ryan M.
2016-01-05
© 2016 American Chemical Society. In designing organic materials for electronics applications, particularly for organic photovoltaics (OPV), the ionization potential (IP) of the donor and the electron affinity (EA) of the acceptor play key roles. This makes OPV design an appealing application for computational chemistry since IPs and EAs are readily calculable from most electronic structure methods. Unfortunately reliable, high-accuracy wave function methods, such as coupled cluster theory with single, double, and perturbative triples [CCSD(T)] in the complete basis set (CBS) limit are too expensive for routine applications to this problem for any but the smallest of systems. One solution is to calibrate approximate, less computationally expensive methods against a database of high-accuracy IP/EA values; however, to our knowledge, no such database exists for systems related to OPV design. The present work is the first of a multipart study whose overarching goal is to determine which computational methods can be used to reliably compute IPs and EAs of electron acceptors. This part introduces a database of 24 known organic electron acceptors and provides high-accuracy vertical IP and EA values expected to be within ±0.03 eV of the true non-relativistic, vertical CCSD(T)/CBS limit. Convergence of IP and EA values toward the CBS limit is studied systematically for the Hartree-Fock, MP2 correlation, and beyond-MP2 coupled cluster contributions to the focal point estimates.
International Nuclear Information System (INIS)
Kurian, P.; Verzegnassi, C.
2016-01-01
We consider in a quantum field theory framework the effects of a classical magnetic field on the spin and orbital angular momentum (OAM) of a free electron. We derive formulae for the changes in the spin and OAM due to the introduction of a general classical background field. We consider then a constant magnetic field, in which case the relevant expressions of the effects become much simpler and conversions between spin and OAM become readily apparent. An estimate of the expectation values for a realistic electron state is also given. Our findings may be of interest to researchers in spintronics and the field of quantum biology, where electron spin has been implicated on macroscopic time and energy scales. - Highlights: • We present the first field theory treatment of magnetic changes in electron spin. • Changes in spin and orbital angular momentum (OAM) are correlated and calculated. • Expectation values of spin–OAM changes for a realistic electron state are computed. • Earth's magnetic field produces non-negligible changes in spin of a few percent. • Results apply to spin–OAM conversion in electron vortex beams and quantum biology.
Sharma, Lalita; Sahoo, Bijaya Kumar; Malkar, Pooja; Srivastava, Rajesh
2018-01-01
A relativistic coupled-cluster theory is implemented to study electron impact excitations of atomic species. As a test case, the electron impact excitations of the 3 s 2 S 1/2-3 p 2 P 1/2;3/2 resonance transitions are investigated in the singly charged magnesium (Mg+) ion using this theory. Accuracies of wave functions of Mg+ are justified by evaluating its attachment energies of the relevant states and compared with the experimental values. The continuum wave function of the projectile electron are obtained by solving Dirac equations assuming distortion potential as static potential of the ground state of Mg+. Comparison of the calculated electron impact excitation differential and total cross-sections with the available measurements are found to be in very good agreements at various incident electron energies. Further, calculations are carried out in the plasma environment in the Debye-Hückel model framework, which could be useful in the astrophysics. Influence of plasma strength on the cross-sections as well as linear polarization of the photon emission in the 3 p 2 P 3/2-3 s 2 S 1/2 transition is investigated for different incident electron energies.
A genetic approach to the presentation of physics: the case of quantum theory
International Nuclear Information System (INIS)
Tzanakis, C.; Coutsomitros, C.
1988-01-01
The conventional approach to the writing of physics textbooks and its inadequacy as regards providing an exhaustive understanding of physical ideas and concepts are discussed by means of two examples taken from quantum theory: Planck's law of black-body radiation and Schroedinger's equation in non-relativistic quantum mechanics. We propose a different approach, which we call the genetic approach, and we analyse it via consideration of the above-mentioned examples. (author)
Höfener, S.; Gomes, A.S.P.; Visscher, L.
2012-01-01
In this article, we present a consistent derivation of a density functional theory (DFT) based embedding method which encompasses wave-function theory-in-DFT (WFT-in-DFT) and the DFT-based subsystem formulation of response theory (DFT-in-DFT) by Neugebauer [J. Neugebauer, J. Chem. Phys. 131, 084104
Regeta, Khrystyna; Bannwarth, Christoph; Grimme, Stefan; Allan, Michael
2015-06-28
The technique of low energy (0-30 eV) electron impact spectroscopy, originally developed for gas phase molecules, is applied to room temperature ionic liquids (IL). Electron energy loss (EEL) spectra recorded near threshold, by collecting 0-2 eV electrons, are largely continuous, assigned to excitation of a quasi-continuum of high overtones and combination vibrations of low-frequency modes. EEL spectra recorded by collecting 10 eV electrons show predominantly discrete vibrational and electronic bands. The vibrational energy-loss spectra correspond well to IR spectra except for a broadening (∼0.04 eV) caused by the liquid surroundings, and enhanced overtone activity indicating a contribution from resonant excitation mechanism. The spectra of four representative ILs were recorded in the energy range of electronic excitations and compared to density functional theory multireference configuration interaction (DFT/MRCI) calculations, with good agreement. The spectra up to about 8 eV are dominated by π-π* transitions of the aromatic cations. The lowest bands were identified as triplet states. The spectral region 2-8 eV was empty in the case of a cation without π orbitals. The EEL spectrum of a saturated solution of methylene green in an IL band showed the methylene green EEL band at 2 eV, indicating that ILs may be used as a host to study nonvolatile compounds by this technique in the future.
Directory of Open Access Journals (Sweden)
Yosslen Aray
2017-11-01
Full Text Available The nature of the electron density localization in a MoS2 monolayer under 0 % to 11% tensile strain has been systematically studied by means of a localized electron detector function and the Quantum Theory of atoms in molecules. At 10% tensile strain, this monolayer become metallic. It was found that for less than 6.5% of applied stress, the same atomic structure of the equilibrium geometry (0% strain is maintained; while over 6.5% strain induces a transformation to a structure where the sulfur atoms placed on the top and bottom layer form S2 groups. The localized electron detector function shows the presence of zones of highly electron delocalization extending throughout the Mo central layer. For less than 10% tensile strain, these zones comprise the BCPs and the remainder CPs in separates regions of the space; while for the structures beyond 10% strain, all the critical points are involved in a region of highly delocalized electrons that extends throughout the material. This dissimilar electron localization pattern is like to that previously reported for semiconductors such as Ge bulk and metallic systems such as transition metals bulk.
Theory and design of broadband matching networks applied electricity and electronics
Chen, Wai-Kai
1976-01-01
Theory and Design of Broadband Matching Networks centers on the network theory and its applications to the design of broadband matching networks and amplifiers. Organized into five chapters, this book begins with a description of the foundation of network theory. Chapter 2 gives a fairly complete exposition of the scattering matrix associated with an n-port network. Chapter 3 considers the approximation problem along with a discussion of the approximating functions. Chapter 4 explains the Youla's theory of broadband matching by illustrating every phase of the theory with fully worked out examp
Hermann, Gunter; Pohl, Vincent; Tremblay, Jean Christophe
2017-10-30
In this contribution, we extend our framework for analyzing and visualizing correlated many-electron dynamics to non-variational, highly scalable electronic structure method. Specifically, an explicitly time-dependent electronic wave packet is written as a linear combination of N-electron wave functions at the configuration interaction singles (CIS) level, which are obtained from a reference time-dependent density functional theory (TDDFT) calculation. The procedure is implemented in the open-source Python program detCI@ORBKIT, which extends the capabilities of our recently published post-processing toolbox (Hermann et al., J. Comput. Chem. 2016, 37, 1511). From the output of standard quantum chemistry packages using atom-centered Gaussian-type basis functions, the framework exploits the multideterminental structure of the hybrid TDDFT/CIS wave packet to compute fundamental one-electron quantities such as difference electronic densities, transient electronic flux densities, and transition dipole moments. The hybrid scheme is benchmarked against wave function data for the laser-driven state selective excitation in LiH. It is shown that all features of the electron dynamics are in good quantitative agreement with the higher-level method provided a judicious choice of functional is made. Broadband excitation of a medium-sized organic chromophore further demonstrates the scalability of the method. In addition, the time-dependent flux densities unravel the mechanistic details of the simulated charge migration process at a glance. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
Farzanehpour, M.; Tokatly, I. V.
2014-11-01
We present a rigorous formulation of the time-dependent density-functional theory for interacting lattice electrons strongly coupled to cavity photons. We start with an example of one particle on a Hubbard dimer coupled to a single photonic mode, which is equivalent to the single mode spin-boson model or the quantum Rabi model. For this system we prove that the electron-photon wave function is a unique functional of the electronic density and the expectation value of the photonic coordinate, provided the initial state and the density satisfy a set of well defined conditions. Then we generalize the formalism to many interacting electrons on a lattice coupled to multiple photonic modes and prove the general mapping theorem. We also show that for a system evolving from the ground state of a lattice Hamiltonian any density with a continuous second time derivative is locally v representable.
Becker, A; Faisal, F
2001-03-26
Recently observed momentum distribution of doubly charged recoil-ions of atoms produced by femtosecond infrared laser pulses is analyzed using the so-called intense-field many-body S-matrix theory. Observed characteristics of the momentum distributions, parallel and perpendicular to the polarization axis, are reproduced by the theory. It is shown that correlated energy-sharing between the two electrons in the intermediate state and their 'Volkov-dressing' in the final state, can explain the origin of these characteristics.
Oberhofer, Harald; Blumberger, Jochen
2010-12-28
We present a plane wave basis set implementation for the calculation of electronic coupling matrix elements of electron transfer reactions within the framework of constrained density functional theory (CDFT). Following the work of Wu and Van Voorhis [J. Chem. Phys. 125, 164105 (2006)], the diabatic wavefunctions are approximated by the Kohn-Sham determinants obtained from CDFT calculations, and the coupling matrix element calculated by an efficient integration scheme. Our results for intermolecular electron transfer in small systems agree very well with high-level ab initio calculations based on generalized Mulliken-Hush theory, and with previous local basis set CDFT calculations. The effect of thermal fluctuations on the coupling matrix element is demonstrated for intramolecular electron transfer in the tetrathiafulvalene-diquinone (Q-TTF-Q(-)) anion. Sampling the electronic coupling along density functional based molecular dynamics trajectories, we find that thermal fluctuations, in particular the slow bending motion of the molecule, can lead to changes in the instantaneous electron transfer rate by more than an order of magnitude. The thermal average, ()(1/2)=6.7 mH, is significantly higher than the value obtained for the minimum energy structure, |H(ab)|=3.8 mH. While CDFT in combination with generalized gradient approximation (GGA) functionals describes the intermolecular electron transfer in the studied systems well, exact exchange is required for Q-TTF-Q(-) in order to obtain coupling matrix elements in agreement with experiment (3.9 mH). The implementation presented opens up the possibility to compute electronic coupling matrix elements for extended systems where donor, acceptor, and the environment are treated at the quantum mechanical (QM) level.
Energy Technology Data Exchange (ETDEWEB)
De Avillez, Miguel A. [Department of Mathematics, University of Évora, R. Romão Ramalho 59, 7000 Évora (Portugal); Breitschwerdt, Dieter, E-mail: mavillez@galaxy.lca.uevora.pt [Zentrum für Astronomie und Astrophysik, Technische Universität Berlin, Hardenbergstrasse 36, D-10623 Berlin (Germany)
2017-09-01
Tracking the thermal evolution of plasmas, characterized by an n -distribution, using numerical simulations, requires the determination of the emission spectra and of the radiative losses due to free–free emission from the corresponding temperature-averaged and total Gaunt factors. Detailed calculations of the latter are presented and associated with n -distributed electrons with the parameter n ranging from 1 (corresponding to the Maxwell–Boltzmann distribution) to 100. The temperature-averaged and total Gaunt factors with decreasing n tend toward those obtained with the Maxwell–Boltzmann distribution. Radiative losses due to free–free emission in a plasma evolving under collisional ionization equilibrium conditions and composed by H, He, C, N, O, Ne, Mg, Si, S, and Fe ions, are presented. These losses decrease with a decrease in the parameter n , reaching a minimum when n = 1, and thus converge with the loss of thermal plasma. Tables of the thermal-averaged and total Gaunt factors calculated for n -distributions, and a wide range of electron and photon energies, are presented.
Periyasamy, Ganga; Remacle, F
2009-08-01
The electronic properties of the neutral, positively and negatively charged bare Au(55), passivated Au(55)(PH(3))(12), Au(55)(PH(3))(12)Cl(6), and solvated Au(55)(PH(3))(12)Cl(6) 54 H(2)O clusters are studied using density functional theory. The presence of Cl atoms in the ligand shell favors a nonmetallic behavior while a more metallic behavior is induced by explicit solvation of Au(55)(PH(3))(12)Cl(6) with water molecules. The trends observed in the electronic properties upon ligation and solvation are in agreement with experimental studies.
Quantum theory of incoherent THz emission of an interacting electron-ion plasma
Richter, M.; Schaarschmidt, M.; Knorr, A.; Hoyer, W.; Moloney, J. V.; Wright, E. M.; Kira, M.; Koch, S. W.
2005-05-01
The THz spectrum of the spontaneous emission of an interacting electron-ion gas, recently observed in laser pulse ionized air, is theoretically analyzed. Using the correlation expansion of the involved many particle system, the contribution of electron-molecule and electron-ion collisions to the transitions in the free electron continuum are treated. Depending on the particle density and the ion distribution, electromagnetic emission is found from the terahertz range up to optical frequencies.
Electron-electron bound states in parity-preserving QED3
International Nuclear Information System (INIS)
Belich, H.; Helayel-Neto, J.A.; Centro Brasileiro de Pesquisas Fisicas; Cima, O.M. del; Ferreira Junior, M.M.; Maranhao Univ., Sao Luis, MA
2002-04-01
By considering the Higgs mechanism in the framework of a parity-preserving Planar Quantum Electrodynamics, one shows that an attractive electron-electron interaction may dominate. The e - e - interaction potential emerges as the non-relativistic limit of the Moeller scattering amplitude and it results attractive with a suitable choice of parameters. Numerically values of the e - e - binding energy are obtained by solving the two-dimensional Schroedinger equation. The existence of bound states is a strong indicative that this model may be adopted to address the pairing mechanism of high-T c superconductivity. (author)
Electron-electron bound states in parity-preserving QED{sub 3}
Energy Technology Data Exchange (ETDEWEB)
Belich, H.; Helayel-Neto, J.A. [Universidade Catolica do Petropolis, RJ (Brazil). Grupo de Fisica Teorica]|[Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Coordenacao de Teoria de Campos e Particulas; Cima, O.M. del [Universidade Catolica do Petropolis, RJ (Brazil). Grupo de Fisica Teorica; Ferreira Junior, M.M. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Coordenacao de Teoria de Campos e Particulas]|[Maranhao Univ., Sao Luis, MA (Brazil). Dept. de Fisica
2002-04-01
By considering the Higgs mechanism in the framework of a parity-preserving Planar Quantum Electrodynamics, one shows that an attractive electron-electron interaction may dominate. The e{sup -}e{sup -} interaction potential emerges as the non-relativistic limit of the Moeller scattering amplitude and it results attractive with a suitable choice of parameters. Numerically values of the e{sup -}e{sup -} binding energy are obtained by solving the two-dimensional Schroedinger equation. The existence of bound states is a strong indicative that this model may be adopted to address the pairing mechanism of high-T{sub c} superconductivity. (author)
Electron-electron bound states in parity-preserving QED sub 3
Belich, H; Helayel-Neto, J A; Monteiro del Cima, O
2002-01-01
By considering the Higgs mechanism in the framework of a parity-preserving Planar Quantum Electrodynamics, one shows that an attractive electron-electron interaction may dominate. The e sup - e sup - interaction potential emerges as the non-relativistic limit of the Moeller scattering amplitude and it results attractive with a suitable choice of parameters. Numerically values of the e sup - e sup - binding energy are obtained by solving the two-dimensional Schroedinger equation. The existence of bound states is a strong indicative that this model may be adopted to address the pairing mechanism of high-T sub c superconductivity.
To the theory of the Pierce instability of neutralized electron flows
International Nuclear Information System (INIS)
Ignatov, A.M.; Rukhadze, A.A.
1984-01-01
The Pierce instability of a nonrelativistic electron beam in an exernal fi inite magnetic field is investigated. Analytical expressions for a critical electron density in limiting cases of strong or weak magnetic field have been fo ound. The critical electron density is shown to increase with a decrease in the magnetic field strength
Chang, Liang-Te; And Others
A study was conducted to develop the electronic technical competencies of duty and task analysis by using a revised DACUM (Developing a Curriculum) method, a questionnaire survey, and a fuzzy synthesis operation. The revised DACUM process relied on inviting electronics trade professionals to analyze electronic technology for entry-level…
Induced gravity in quantum theory in a curved space
International Nuclear Information System (INIS)
Etim, E.
1983-01-01
The reason for interest in the unorthodox view of first order (about R(x)) gravity as a matter-induced quantum effect is really to find an argument not to quantise it. According to this view quantum gravity should be constructed with an action which is, at least, quadratic in the scalar curvature R(x). Such a theory will not contain a dimensional parameter, like Newton's constant, and would probably be renormalisable. This lecture is intended to acquaint the non-expert with the phenomenon of induction of the scalar curvature term in the matter Lagrangian in a curved space in both relativistic and non-relativistic quantum theories
International Nuclear Information System (INIS)
Säkkinen, Niko; Leeuwen, Robert van; Peng, Yang; Appel, Heiko
2015-01-01
We study ground-state properties of a two-site, two-electron Holstein model describing two molecules coupled indirectly via electron-phonon interaction by using both exact diagonalization and self-consistent diagrammatic many-body perturbation theory. The Hartree and self-consistent Born approximations used in the present work are studied at different levels of self-consistency. The governing equations are shown to exhibit multiple solutions when the electron-phonon interaction is sufficiently strong, whereas at smaller interactions, only a single solution is found. The additional solutions at larger electron-phonon couplings correspond to symmetry-broken states with inhomogeneous electron densities. A comparison to exact results indicates that this symmetry breaking is strongly correlated with the formation of a bipolaron state in which the two electrons prefer to reside on the same molecule. The results further show that the Hartree and partially self-consistent Born solutions obtained by enforcing symmetry do not compare well with exact energetics, while the fully self-consistent Born approximation improves the qualitative and quantitative agreement with exact results in the same symmetric case. This together with a presented natural occupation number analysis supports the conclusion that the fully self-consistent approximation describes partially the bipolaron crossover. These results contribute to better understanding how these approximations cope with the strong localizing effect of the electron-phonon interaction
Bohr quantum theory of the magnetic monopoles and classical electron electromagnetic mass problem
Pankovic, Vladan
2010-01-01
In the first part of this work we apply Bohr (old or naive quantum atomic) theory for analysis of the remarkable electro-dynamical problem of magnetic monopoles. We reproduce formally exactly some basic elements of the Dirac magnetic monopoles theory, especially Dirac electric/magnetic charge quantization condition. It follows after application of Bohr theory at the system, simply called magnetic monopole "atom", consisting of the practically standing, massive magnetic monopole as the "nucleu...
Petit, L; Paudyal, D; Mudryk, Y; Gschneidner, K A; Pecharsky, V K; Lüders, M; Szotek, Z; Banerjee, R; Staunton, J B
2015-11-13
We explain a profound complexity of magnetic interactions of some technologically relevant gadolinium intermetallics using an ab initio electronic structure theory which includes disordered local moments and strong f-electron correlations. The theory correctly finds GdZn and GdCd to be simple ferromagnets and predicts a remarkably large increase of Curie temperature with a pressure of +1.5 K kbar(-1) for GdCd confirmed by our experimental measurements of +1.6 K kbar(-1). Moreover, we find the origin of a ferromagnetic-antiferromagnetic competition in GdMg manifested by noncollinear, canted magnetic order at low temperatures. Replacing 35% of the Mg atoms with Zn removes this transition, in excellent agreement with long-standing experimental data.
Petit, L.; Paudyal, D.; Mudryk, Y.; Gschneidner, K. A.; Pecharsky, V. K.; Lüders, M.; Szotek, Z.; Banerjee, R.; Staunton, J. B.
2015-11-01
We explain a profound complexity of magnetic interactions of some technologically relevant gadolinium intermetallics using an ab initio electronic structure theory which includes disordered local moments and strong f -electron correlations. The theory correctly finds GdZn and GdCd to be simple ferromagnets and predicts a remarkably large increase of Curie temperature with a pressure of +1.5 K kbar-1 for GdCd confirmed by our experimental measurements of +1.6 K kbar-1 . Moreover, we find the origin of a ferromagnetic-antiferromagnetic competition in GdMg manifested by noncollinear, canted magnetic order at low temperatures. Replacing 35% of the Mg atoms with Zn removes this transition, in excellent agreement with long-standing experimental data.
Nonlinear theory of a free electron laser with a helical wiggler and an axial guide magnetic field
Directory of Open Access Journals (Sweden)
N. S. Ginzburg
2013-09-01
Full Text Available A 1D nonlinear theory of a free electron laser (FEL with a helical wiggler and an axial guide magnetic field is developed based on averaged equations of the electron motion. By averaging we separated two different cases of the e-beam/rf-wave interaction. The first one corresponds to the traditional wiggler synchronism (resonance of rf wave with the electrons moving along stationary helical trajectories. The second one corresponds to combination resonances distinguishing by excitation of oscillation of the electrons near the stationary helical trajectory. Comparative analysis of the FEL operation in different regimes has been studied under the traditional wiggler synchronism condition. It was shown that FELs operated far from cyclotron resonance (including a reversed guide field orientation possess low sensitivity to the initial velocity spread in the driving beam resulting in high electron efficiency. In contrast, under the weak guide field (the gyrofrequency is less than the bounce frequency of a conventional orientation, the FEL efficiency is restricted by a significant increase in the transverse velocity of the electrons during the interaction with the rf wave that results in violation of the synchronism conditions and is accompanied by electron current losses. An additional mechanism of FEL efficiency enhancement under the conventional guide field orientation in the conditions when the gyrofrequency is higher than the bounce frequency, based on the dependence of the effective mass of the oscillating electrons on their energy, was demonstrated. Results of the theoretical analysis are compared with the results of experimental studies of FEL oscillators. The specific features of energy extraction from the electron beam under condition of an abnormal Doppler effect in the case of the combination resonance are described. This regime is beneficial to increase radiation frequency keeping wiggler period and electron energies.
Mendive-Tapia, Eduardo; Staunton, Julie B.
2017-05-01
We describe a disordered local moment theory for long-period magnetic phases and investigate the temperature and magnetic field dependence of the magnetic states in the heavy rare earth elements (HREs), namely, paramagnetic, conical and helical antiferromagnetic (HAFM), fan, and ferromagnetic (FM) states. We obtain a generic HRE magnetic phase diagram which is consequent on the response of the common HRE valence electronic structure to f -electron magnetic moment ordering. The theory directly links the first-order HAFM-FM transition to the loss of Fermi surface nesting, induced by this magnetic ordering, as well as provides a template for analyzing the other phases and exposing where f -electron correlation effects are particularly intricate. Gadolinium, for a range of hexagonal, close-packed lattice constants c and a , is the prototype, described ab initio, and applications to other HREs are made straightforwardly by scaling the effective pair and quartic local moment interactions that emerge naturally from the theory with de Gennes factors and choosing appropriate lanthanide-contracted c and a values.
Developments in the kinetic theories of ion and electron swarms in the 1960s and 70s
Skullerud, H. R.
2017-04-01
The two decades between 1960 to 1980 saw quite a fantastic development in diverse areas in physics, and so also in the quantitative theoretical treatment and deeper understanding of the behaviour of isolated electrons and ions in gases—that is ‘charged particle swarm physics’. The evolution in swarm theory was strongly correlated with the contemporary advances in computer technology and the emergence of new and accurate experimental methods for finding charged particle transport parameters, as drift velocities, diffusion coefficients and reaction rates, and also with developments in neighbouring fields as plasma physics and the physics of electronic and molecular collisions. In 1960, low energy electron behaviour could already be calculated with reasonable accuracy in the so-called two-term approximation, while ion behaviour could only be treated at weak electric fields. By 1980, reasonably complete theories had been developed for perhaps most cases in interest—which is reflected in a number of reviews, books and journal articles published in the early 1980s. We will present a journey through the developments in this period and the basic theories behind the Boltzmann equation and Maxwell’s transfer equations. We will also indicate how the interaction between different studies of the same basic processes have led to the elimination of shortcomings and a better understanding.
Electron traps in polar liquids. An application of the formalism of the random field theory
International Nuclear Information System (INIS)
Hilczer, M.; Bartczak, W.M.
1992-01-01
The potential energy surface in a disordered medium is described, using the concepts of the mathematical theory of random fields. The statistics of trapping sites (the regions of an excursion of the random field) is obtained for liquid methanol as a numerical example of the theory. (author). 15 refs, 4 figs
International Nuclear Information System (INIS)
Yang, Judith C.; Nuzzo, Ralph G.; Johnson, Duane; Frenkel, Anatoly
2008-01-01
The distinguishing feature of our collaborative program of study is the focus it brings to emergent phenomena originating from the unique structural/electronic environments found in nanoscale materials. We exploit and develop frontier methods of atomic-scale materials characterization based on electron microscopy (Yang) and synchrotron X-ray absorption spectroscopy (Frenkel) that are in turn coupled innately with advanced first principles theory and methods of computational modeling (Johnson). In the past year we have made significant experimental advances that have led to important new understandings of the structural dynamics of what are unquestionably the most important classes of heterogeneous catalysts-the materials used to both produce and mitigate the consequences of the use of liquid hydrocarbon fuels.
Theory of high-field electronic transport in bulk ZnS and ZnSe
Brennan, Kevin
1988-01-01
This paper theoretically investigates the nature of electronic transport and the high-energy tails of the electron distribution functions in bulk ZnSe and ZnS as a function of the applied electric field were investigated using calculations based on an ensemble Monte Carlo model. The calculations include the full details of the first two conduction bands as well as the full-order treatment of the electron-phonon scattering mechanisms. Results of high-field electronic transport calculations show that the electron energy distribution function is significanty cooler in ZnS than in ZnSe at comparable electric field strengths. The cooler distribution in ZnS is due to the much greater electron scattering rate. Consequently, it is more difficult to achieve carrier heating to comparable energies in ZnS than in ZnSe.
Energy Technology Data Exchange (ETDEWEB)
Diez Muino, R. [Donostia International Physics Center (DIPC), San Sebastian (Spain) and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)]. E-mail: rdm@sc.ehu.es; Rolles, D. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany); Garcia de Abajo, F.J. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Centro Mixto CSIC-UPV/EHU, San Sebastian (Spain); Fadley, C.S. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Department of Physics, University of California at Davis, Davis, CA (United States); Van Hove, M.A. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Department of Physics, University of California at Davis, Davis, CA (United States); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)
2002-08-14
We use multiple scattering in non-spherical potentials (MSNSP) to calculate the angular distributions of electrons photoemitted from the 1s shells of CO and N{sub 2} gas-phase molecules with fixed-in-space orientations. For low photoelectron kinetic energies (E<50 eV), as appropriate to certain shape resonances, the electron scattering must be represented by non-spherical scattering potentials, which are naturally included in our formalism. Our calculations accurately reproduce the experimental angular patterns recently measured by several groups, including those at the shape-resonance energies. The MSNSP theory is thus an efficient method to calculate the scattering states of low-energy electrons in small low-symmetry systems. (author). Letter-to-the-editor.
Energy Technology Data Exchange (ETDEWEB)
Diez Muino, R.; Rolles, D.; Garcia de Abajo, F.J.; Fadley, C.S.; Van Hove, M.A.
2001-09-06
We use multiple scattering in non-spherical potentials (MSNSP) to calculate the angular distributions of electrons photoemitted from the 1s-shells of CO and N2 gas-phase molecules with fixed-in-space orientations. For low photoelectron kinetic energies (E<50 eV), as appropriate to certain shape-resonances, the electron scattering must be represented by non-spherical scattering potentials, which are naturally included in our formalism. Our calculations accurately reproduce the experimental angular patterns recently measured by several groups, including those at the shape-resonance energies. The MSNSP theory thus enhances the sensitivity to spatial electronic distribution and dynamics, paving the way toward their determination from experiment.
Directory of Open Access Journals (Sweden)
Umer Mehmood
2015-01-01
Full Text Available The molecular structures and UV-visible absorption spectra of complex photosensitizers comprising oxadiazole isomers as the π-bridges were analyzed by density functional theory (DFT and time-dependent DFT. The ground state and excited state oxidation potentials, HOMOs and LUMOs energy levels, and electron injection from the dyes to semiconductor TiO2 have been computed in vacuum here. The results show that all of the dyes may potentially be good photosensitizers in DSSC. To justify the simulation basis, N3 dye was also simulated under the similar conditions. Simulated absorption spectrum, HOMO, LUMO, and band gap values of N3 were compared with the experimental values. We also computed the electronic structure properties and absorption spectra of dye/(TiO28 systems to elucidate the electron injection efficiency at the interface. This work is expected to give proper orientation for experimental synthesis.
Goings, Joshua James
Time-dependent electronic structure theory has the power to predict and probe the ways electron dynamics leads to useful phenomena and spectroscopic data. Here we report several advances and extensions of broken-symmetry time-dependent electronic structure theory in order to capture the flexibility required to describe non-equilibrium spin dynamics, as well as electron dynamics for chiroptical properties and vibrational effects. In the first half, we begin by discussing the generalization of self-consistent field methods to the so-called two-component structure in order to capture non-collinear spin states. This means that individual electrons are allowed to take a superposition of spin-1/2 projection states, instead of being constrained to either spin-up or spin-down. The system is no longer a spin eigenfunction, and is known a a spin-symmetry broken wave function. This flexibility to break spin symmetry may lead to variational instabilities in the approximate wave function, and we discuss how these may be overcome. With a stable non-collinear wave function in hand, we then discuss how to obtain electronic excited states from the non-collinear reference, along with associated challenges in their physical interpretation. Finally, we extend the two-component methods to relativistic Hamiltonians, which is the proper setting for describing spin-orbit driven phenomena. We describe the first implementation of the explicit time propagation of relativistic two-component methods and how this may be used to capture spin-forbidden states in electronic absorption spectra. In the second half, we describe the extension of explicitly time-propagated wave functions to the simulation of chiroptical properties, namely circular dichroism (CD) spectra of chiral molecules. Natural circular dichroism, that is, CD in the absence of magnetic fields, originates in the broken parity symmetry of chiral molecules. This proves to be an efficient method for computing circular dichroism spectra
Electron-Cloud Simulation and Theory for High-Current Heavy-Ion Beams
International Nuclear Information System (INIS)
Cohen, R; Friedman, A; Lund, S; Molvik, A; Lee, E; Azevedo, T; Vay, J; Stoltz, P; Veitzer, S
2004-01-01
Stray electrons can arise in positive-ion accelerators for heavy ion fusion or other applications as a result of ionization of ambient gas or gas released from walls due to halo-ion impact, or as a result of secondary- electron emission. We summarize the distinguishing features of electron cloud issues in heavy-ion-fusion accelerators and a plan for developing a self-consistent simulation capability for heavy-ion beams and electron clouds. We also present results from several ingredients in this capability: (1) We calculate the electron cloud produced by electron desorption from computed beam-ion loss, which illustrates the importance of retaining ion reflection at the walls. (2) We simulate of the effect of specified electron cloud distributions on ion beam dynamics. We consider here electron distributions with axially varying density, centroid location, or radial shape, and examine both random and sinusoidally varying perturbations. We find that amplitude variations are most effective in spoiling ion beam quality, though for sinusoidal variations which match the natural ion beam centroid oscillation or breathing mode frequencies, the centroid and shape perturbations can also have significant impact. We identify an instability associated with a resonance between the beam-envelope ''breathing'' mode and the electron perturbation. We estimate its growth rate, which is moderate (compared to the reciprocal of a typical pulse duration). One conclusion from this study is that heavy-ion beams are surprisingly robust to electron clouds, compared to a priori expectations. (3) We report first results from a long-timestep algorithm for electron dynamics, which holds promise for efficient simultaneous solution of electron and ion dynamics
Electron-cloud simulation and theory for high-current heavy-ion beams
Directory of Open Access Journals (Sweden)
R. H. Cohen
2004-12-01
Full Text Available Stray electrons can arise in positive-ion accelerators for heavy-ion fusion or other applications as a result of ionization of ambient gas or gas released from walls due to halo-ion impact, or as a result of secondary-electron emission. We summarize the distinguishing features of electron-cloud issues in heavy-ion-fusion accelerators and a plan for developing a self-consistent simulation capability for heavy-ion beams and electron clouds (also applicable to other accelerators. We also present results from several ingredients in this capability. (1 We calculate the electron cloud produced by electron desorption from computed beam-ion loss, which illustrates the importance of retaining ion reflection at the walls. (2 We simulate the effect of specified electron-cloud distributions on ion beam dynamics. We consider here electron distributions with axially varying density, centroid location, or radial shape, and examine both random and sinusoidally varying perturbations. We find that amplitude variations are most effective in spoiling ion beam quality, though for sinusoidal variations which match the natural ion beam centroid oscillation or breathing-mode frequencies, the centroid and shape perturbations can also have significant impact. We identify an instability associated with a resonance between the beam-envelope “breathing” mode and the electron perturbation. We estimate its growth rate, which is moderate (compared to the reciprocal of a typical pulse duration. One conclusion from this study is that heavy-ion beams are surprisingly robust to electron clouds, compared to a priori expectations. (3 We report first results from a long-time-step algorithm for electron dynamics, which holds promise for efficient simultaneous solution of electron and ion dynamics.
Egedal, J.; Le, A.; Daughton, W.; Wetherton, B.; Cassak, P. A.; Chen, L.-J.; Lavraud, B.; Torbert, R. B.; Dorelli, J.; Gershman, D. J.; Avanov, L. A.
2016-10-01
Supported by a kinetic simulation, we derive an exclusion energy parameter EX providing a lower kinetic energy bound for an electron to cross from one inflow region to the other during magnetic reconnection. As by a Maxwell demon, only high-energy electrons are permitted to cross the inner reconnection region, setting the electron distribution function observed along the low-density side separatrix during asymmetric reconnection. The analytic model accounts for the two distinct flavors of crescent-shaped electron distributions observed by spacecraft in a thin boundary layer along the low-density separatrix.
DEFF Research Database (Denmark)
Pennington, Robert S.
In this dissertation, factors affecting electron holographic measurements of the mean inner potential are explored. Electron holography in the transmission electron microscope (TEM) allows for quantitative retrieval of the amplitude and phase of the electron beam. Both the amplitude and the phase...... holography, and this difference is known as the Stobbs factor - therefore, a dataset that allows for good comparison between image simulation and experiment might highlight possible improvements in the simulation software. The factors that affect the mean inner potential are explored through both experiment...
Electron Beam Propagation in a Plasma
Directory of Open Access Journals (Sweden)
Kyoung W. Min
1988-06-01
Full Text Available Electron beam propagation in a fully ionized plasma has been studied using a one-dimensional particle simulation model. We compare the results of electrostatic simulations to those of electromagnetic simulations. The electrostatic results show the essential features of beam-plasma instability which accelerates ambient plasmas. The results also show the heating of ambient plasmas and the trapping of plasmas due to the locally generated electric field. The level of the radiation generated by the same non-relativistic beam is slightly higher than the noise level. We discuss the results in context of the heating of coronal plasma during solar flares.
Theory of inelastic electron tunneling from a localized spin in the impulsive approximation.
Persson, Mats
2009-07-31
A simple expression for the conductance steps in inelastic electron tunneling from spin excitations in a single magnetic atom adsorbed on a nonmagnetic metal surface is derived. The inelastic coupling between the tunneling electron and the spin is via the exchange coupling and is treated in an impulsive approximation using the Tersoff-Hamann approximation for the tunneling between the tip and the sample.
Czech Academy of Sciences Publication Activity Database
Palatinus, Lukáš; Petříček, Václav; Correa, Cinthia Antunes
2015-01-01
Roč. 71, Mar (2015), 235-244 ISSN 0108-7673 R&D Projects: GA ČR GA13-25747S Institutional support: RVO:68378271 Keywords : dynamical diffraction * electron diffraction tomography * electron crystallography Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.307, year: 2014
Heijden, van der Hans
1999-01-01
This paper is concerned with the identification of determinants that influence the use ofbusiness-to-consumer electronic markets. Since the widespread adoption of the Internet, these electronic markets are now commonplace and it becomesincreasingly relevant to identify the factors that influence
Electron-nuclear coupling in time-dependent multicomponent density functional theory
Butriy, Olena O.
2008-01-01
In this thesis we developed the time-dependent version of the multicomponent density functional approach to treat time-dependent electron-nuclear systems. The method enables to describe the electron-nuclear coupling fully quantum mechanically. No Born-Oppenheimer approximation is involved in the
Many-body theory of electron correlations in atoms: RPAE and beyond
International Nuclear Information System (INIS)
Amusia, M.Ya.
1996-01-01
It is demonstrated how the correlations of electrons manifest themselves in photoionization of atoms. The diagrammatical technique, convenient and transparent, is applied to study this and related processes. Choosing as the best one particle the Hartree-Fock approximation, the first considerable step in accounting for electron correlations is made by constructing the Random Phase Approximation with Exchange. Its generalizations are also described, which include rearrangement of electron shells due to vacancies creation and decay. Attention is given to ''two electron-two vacancy'' excitations, formation of the negative ions and their photoionization as well as to satellites and ''shadows''. The direct knock-out of secondary particles, electrons and photons, by photoelectrons is considered. Formation of multiply-charged ions and above threshold phenomena, mainly multistep PCI, are discussed. Future of the domain: new atom-like objects and next steps in theoretical studies are outlined. (author)
Conceptual density functional theory for electron transfer and transport in mesoscopic systems.
Bueno, Paulo R; Miranda, David A
2017-02-22
Molecular and supramolecular systems are essentially mesoscopic in character. The electron self-exchange, in the case of energy fluctuations, or electron transfer/transport, in the case of the presence of an externally driven electrochemical potential, between mesoscopic sites is energetically driven in such a manner where the electrochemical capacitance (C [small mu, Greek, macron] ) is fundamental. Thus, the electron transfer/transport through channels connecting two distinct energetic (ΔE [small mu, Greek, macron] ) and spatially separated mesoscopic sites is capacitively modulated. Remarkably, the relationship between the quantum conductance (G) and the standard electrochemical rate constant (k r ), which is indispensable to understanding the physical and chemical characteristics governing electron exchange in molecular scale systems, was revealed to be related to C [small mu, Greek, macron] , that is, C [small mu, Greek, macron] = G/k r . Accordingly, C [small mu, Greek, macron] is the proportional missing term that controls the electron transfer/transport in mesoscopic systems in a wide-range, and equally it can be understood from first principles density functional quantum mechanical approaches. Indeed the differences in energy between states is calculated (or experimentally accessed) throughout the electrochemical capacitance as ΔE [small mu, Greek, macron] = β/C [small mu, Greek, macron] , and thus constitutes the driving force for G and/or k r , where β is only a proportional constant that includes the square of the unit electron charge times the square of the number of electron particles interchanged.
International Nuclear Information System (INIS)
Schroeder, J. W. R.; Skiff, F.; Howes, G. G.; Kletzing, C. A.; Carter, T. A.; Dorfman, S.
2015-01-01
Wave propagation can be an accurate method for determining material properties. High frequency whistler mode waves (0.7 < ω/|Ω ce | < 1) in an overdense plasma (ω pe > |Ω ce |) are damped primarily by Doppler-shifted electron cyclotron resonance. A kinetic description of whistler mode propagation parallel to the background magnetic field shows that damping is proportional to the parallel electron distribution function. This property enables an experimental determination of the parallel electron distribution function using a measurement of whistler mode wave absorption. The whistler mode wave absorption diagnostic uses this technique on UCLA’s Large Plasma Device (LaPD) to measure the distribution of high energy electrons (5 − 10v te ) with 0.1% precision. The accuracy is limited by systematic effects that need to be considered carefully. Ongoing research uses this diagnostic to investigate the effect of inertial Alfvén waves on the electron distribution function. Results presented here verify experimentally the linear effects of inertial Alfvén waves on the reduced electron distribution function, a necessary step before nonlinear physics can be tested. Ongoing experiments with the whistler mode wave absorption diagnostic are making progress toward the first direct detection of electrons nonlinearly accelerated by inertial Alfvén waves, a process believed to play an important role in auroral generation
Pennington, Robert S.; Coll, Catalina; Estradé, Sònia; Peiró, Francesca; Koch, Christoph T.
2018-01-01
Iterative neural-network-based three-dimensional structural optimization of atomic positions over tens of nanometers is performed using transmission electron microscope (TEM) diffraction data simulated from density functional theory (DFT) all-electron densities, thus retrieving parameter variations along the beam direction. We first use experimental data to show that the GPAW DFT code's all-electron densities are considerably more accurate for electron diffraction calculations compared to conventional isolated-atom scattering factors, and they also compare well to Wien2K DFT simulations. This DFT-TEM combination is then integrated into an iterative neural-network-optimization-based algorithm (PRIMES, parameter retrieval and inversion from multiple electron scattering) to retrieve nanometer-scale ferroelectric polarization domains and strain in theoretical bulklike specimens from TEM data. DFT and isolated-atom methods produce substantially different diffraction patterns and retrieved polarization domain parameters, and DFT is sufficient to retrieve strain properties from a silicon specimen simulated using experimentally derived structure factors. Thus, we show that the improved accuracy, fast computation, and intuitive integration make the GPAW DFT code well suited for three-dimensional materials characterization and demonstrate this using an iterative neural-network algorithm that is verifiable on the mesoscale and, with DFT integration, self-consistent on the nanoscale.
Li, Chen; Requist, Ryan; Gross, E K U
2018-02-28
We perform model calculations for a stretched LiF molecule, demonstrating that nonadiabatic charge transfer effects can be accurately and seamlessly described within a density functional framework. In alkali halides like LiF, there is an abrupt change in the ground state electronic distribution due to an electron transfer at a critical bond length R = R c , where an avoided crossing of the lowest adiabatic potential energy surfaces calls the validity of the Born-Oppenheimer approximation into doubt. Modeling the R-dependent electronic structure of LiF within a two-site Hubbard model, we find that nonadiabatic electron-nuclear coupling produces a sizable elongation of the critical R c by 0.5 bohr. This effect is very accurately captured by a simple and rigorously derived correction, with an M -1 prefactor, to the exchange-correlation potential in density functional theory, M = reduced nuclear mass. Since this nonadiabatic term depends on gradients of the nuclear wave function and conditional electronic density, ∇ R χ(R) and ∇ R n(r, R), it couples the Kohn-Sham equations at neighboring R points. Motivated by an observed localization of nonadiabatic effects in nuclear configuration space, we propose a local conditional density approximation-an approximation that reduces the search for nonadiabatic density functionals to the search for a single function y(n).
Energy Technology Data Exchange (ETDEWEB)
Marana, Naiara L. [Modeling and Molecular Simulations Group, São Paulo State University, UNESP, 17033-360 Bauru, SP (Brazil); Albuquerque, Anderson R. [Federal Institute of Education, Science and Technology of Sertão Pernambucano, 56400-000 Floresta, PE (Brazil); La Porta, Felipe A. [Chemistry Department, Federal Technological University of Paraná, 86036-370 Londrina, PR (Brazil); Longo, Elson [São Paulo State University, Chemistry Institute, UNESP, 14801-907 Araraquara, SP (Brazil); Sambrano, Julio R. [Modeling and Molecular Simulations Group, São Paulo State University, UNESP, 17033-360 Bauru, SP (Brazil)
2016-05-15
Periodic density functional theory calculations with the B3LYP hybrid functional and all-electron Gaussian basis set were performed to simulate the structural and electronic properties as well as the strain and formation energies of single-walled ZnO nanotubes (SWZnONTs) and Carbon nanotubes (SWCNTs) with different chiralities as functions of their diameters. For all SWZnONTs, the band gap, strain energy, and formation energy converge to ~4.5 eV, 0.0 eV/atom, and 0.40 eV/atom, respectively. This result suggests that the nanotubes are formed more easily from the surface than from the bulk. For SWCNTs, the strain energy is always positive, while the formation energy is negative for armchair and zigzag nanotubes, therefore suggesting that these types of nanotubes can be preferentially formed from the bulk. The electronic properties of SWCNTs depend on the chirality; all armchair nanotubes are metallic, while zigzag and chiral nanotubes can be metallic or semiconducting, depending on the n and m vectors. - Graphical abstract: DFT/B3LYP were performed to simulate the structural and electronic properties as well as the strain and formation energies of SWZnONTs and SWCNTs with different chiralities as functions of their diameters. - Highlights: • The energies of SWZnONTs converge for chirality with diameters up 20 Å. • SWCNTs electronic properties depend on the chirality. • The properties of SWZnONTs are very similar to those of monolayer surface.
Aspects of space charge theory applied to dielectric under electron beam irradiation
International Nuclear Information System (INIS)
Oliveira, L.N. de.
1975-01-01
Irradiation of solid dielectric with electron beams has been used as a power full tool in investigations of charge storage and transport in such materials. Some of the results that have been obtained in this area are reviewed and the formulation of a transport equation for excess charge in irradiated insulators is dicussed. This equation is subsequently applied to various experimental set-ups. It is found that space charge effects play an essential role in the establishment of stationary currents in samples subject to quasi-penetrating electron beams. Such effects may, however, be neglected for low electron ranges. Theoretical results are in good agreement with experimental findings by Spear (1955)
The application of cavity theory to the dosimetry of electron fields
International Nuclear Information System (INIS)
Lowe, D.
1979-01-01
A number of criticisms are made of the theoretical derivation of an expression for the cavity correction factor f for electron beams (Almond, P.R., and McCray, K., 1970, Phys. Med. Biol., vol. 15, 335). Calculations of mass stopping power ratios and the response of LiF for various electron energies (3.55 to 25.04 MeV) are in disagreement with those calculated and measured by Paliwal and Almond (1975, Phys. Med. Biol., vol. 20, 547). Almond and McCray's attempt to explain the energy response of LiF dosemeters to high energy electrons is therefore inconclusive. (U.K.)
Theory of Rapidly Oscillating Electron Angular Distributions in Slow Ion-Atom Collisions
Energy Technology Data Exchange (ETDEWEB)
Macek, J.H.; Ovchinnikov, S.Y. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1501 (United States)]|[Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States)
1998-03-01
A general expression for the ionization amplitude in slow ion-atom collisions is derived. The expression is inverted to obtain adiabatic electronic wave functions at complex values of the internuclear distance. It is shown that beating between {sigma} and {pi} components of electronic wave functions gives rise to rapid oscillations of electron angular distributions with ion velocity v . These rapid oscillations measure the real part of that eigenvalue whose imaginary part gives the well-known Wannier exponent. {copyright} {ital 1998} {ital The American Physical Society}
Bajaj, Akash; Janet, Jon Paul; Kulik, Heather J.
2017-11-01
The flat-plane condition is the union of two exact constraints in electronic structure theory: (i) energetic piecewise linearity with fractional electron removal or addition and (ii) invariant energetics with change in electron spin in a half filled orbital. Semi-local density functional theory (DFT) fails to recover the flat plane, exhibiting convex fractional charge errors (FCE) and concave fractional spin errors (FSE) that are related to delocalization and static correlation errors. We previously showed that DFT+U eliminates FCE but now demonstrate that, like other widely employed corrections (i.e., Hartree-Fock exchange), it worsens FSE. To find an alternative strategy, we examine the shape of semi-local DFT deviations from the exact flat plane and we find this shape to be remarkably consistent across ions and molecules. We introduce the judiciously modified DFT (jmDFT) approach, wherein corrections are constructed from few-parameter, low-order functional forms that fit the shape of semi-local DFT errors. We select one such physically intuitive form and incorporate it self-consistently to correct semi-local DFT. We demonstrate on model systems that jmDFT represents the first easy-to-implement, no-overhead approach to recovering the flat plane from semi-local DFT.
Bhatia, Anand K.
2008-01-01
Applications of the hybrid theory to the scattering of electrons from Ile+ and Li++ and resonances in these systems, A. K. Bhatia, NASA/Goddard Space Flight Center- The Hybrid theory of electron-hydrogen elastic scattering [I] is applied to the S-wave scattering of electrons from He+ and Li++. In this method, both short-range and long-range correlations are included in the Schrodinger equation at the same time. Phase shifts obtained in this calculation have rigorous lower bounds to the exact phase shifts and they are compared with those obtained using the Feshbach projection operator formalism [2], the close-coupling approach [3], and Harris-Nesbet method [4]. The agreement among all the calculations is very good. These systems have doubly-excited or Feshbach resonances embedded in the continuum. The resonance parameters for the lowest ' S resonances in He and Li+ are calculated and they are compared with the results obtained using the Feshbach projection operator formalism [5,6]. It is concluded that accurate resonance parameters can be obtained by the present method, which has the advantage of including corrections due to neighboring resonances and the continuum in which these resonances are embedded.
Bajaj, Akash; Janet, Jon Paul; Kulik, Heather J
2017-11-21
The flat-plane condition is the union of two exact constraints in electronic structure theory: (i) energetic piecewise linearity with fractional electron removal or addition and (ii) invariant energetics with change in electron spin in a half filled orbital. Semi-local density functional theory (DFT) fails to recover the flat plane, exhibiting convex fractional charge errors (FCE) and concave fractional spin errors (FSE) that are related to delocalization and static correlation errors. We previously showed that DFT+U eliminates FCE but now demonstrate that, like other widely employed corrections (i.e., Hartree-Fock exchange), it worsens FSE. To find an alternative strategy, we examine the shape of semi-local DFT deviations from the exact flat plane and we find this shape to be remarkably consistent across ions and molecules. We introduce the judiciously modified DFT (jmDFT) approach, wherein corrections are constructed from few-parameter, low-order functional forms that fit the shape of semi-local DFT errors. We select one such physically intuitive form and incorporate it self-consistently to correct semi-local DFT. We demonstrate on model systems that jmDFT represents the first easy-to-implement, no-overhead approach to recovering the flat plane from semi-local DFT.
International Nuclear Information System (INIS)
Chaluvadi, Haari; Amami, S M; Madison, Don; Nixon, Kate; Murray, Andrew
2012-01-01
Experimental and Theoretical Triply Differential Cross sections will be presented for low energy electron impact ionization of Ne, CH 4 , and NH 3 . The collision mechanisms responsible for the various structures found in the cross sections will be discussed.
Theory of photon and electron induced reactions: Progress report, July 1, 1986-June 30, 1987
International Nuclear Information System (INIS)
Onley, D.S.; Wright, L.E.
1988-07-01
During the third year of our three-year contract from the Department of Energy, we have made considerable progress or have completed our studies on the following aspects of the general investigation of electron and photon induced reactions; photo- and electro-production of mesons; the radiation tail accompanying elastic electron scattering and pair production; studies involving relativistic shell model; and electrofission coincidence angular distributions. We will report on each of these developments in this paper
International Nuclear Information System (INIS)
Svane, A.; Trygg, J.; Johansson, B.; Eriksson, O.
1997-01-01
Electronic-structure calculations of elemental praseodymium are presented. Several approximations are used to describe the Pr f electrons. It is found that the low-pressure, trivalent phase is well described using either the self-interaction corrected (SIC) local-spin-density (LSD) approximation or the generalized-gradient approximation (GGA) with spin and orbital polarization (OP). In the SIC-LSD approach the Pr f electrons are treated explicitly as localized with a localization energy given by the self-interaction of the f orbital. In the GGA+OP scheme the f-electron localization is described by the onset of spin and orbital polarization, the energetics of which is described by spin-moment formation energy and a term proportional to the total orbital moment, L z 2 . The high-pressure phase is well described with the f electrons treated as band electrons, in either the LSD or the GGA approximations, of which the latter describes more accurately the experimental equation of state. The calculated pressure of the transition from localized to delocalized behavior is 280 kbar in the SIC-LSD approximation and 156 kbar in the GGA+OP approach, both comparing favorably with the experimentally observed transition pressure of 210 kbar. copyright 1997 The American Physical Society
Staunton, J. B.; Ostanin, S.; Razee, S. S.; Gyorffy, B. L.; Szunyogh, L.; Ginatempo, B.; Bruno, Ezio
2004-12-01
Using a first-principles, relativistic electronic structure theory of finite temperature metallic magnetism, we investigate the variation of magnetic anisotropy K with magnetization M in metallic ferromagnets. We apply the theory to the high uniaxial K material, L10-ordered FePt, and find its magnetic easy axis perpendicular to the Fe/Pt layers for all M and K to be proportional to M2 for a broad range of values of M. For small M, near the Curie temperature, the calculations pick out the easy axis for the onset of magnetic order. Our abinitio results for this important magnetic material agree well with recent experimental measurements, whereas the single-ion anisotropy model fails to give the correct qualitative behavior.
Ab-initio Computation of the Electronic, transport, and Bulk Properties of Calcium Oxide.
Mbolle, Augustine; Banjara, Dipendra; Malozovsky, Yuriy; Franklin, Lashounda; Bagayoko, Diola
We report results from ab-initio, self-consistent, local Density approximation (LDA) calculations of electronic and related properties of calcium oxide (CaO) in the rock salt structure. We employed the Ceperley and Alder LDA potential and the linear combination of atomic orbitals (LCAO) formalism. Our calculations are non-relativistic. We implemented the LCAO formalism following the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). The BZW-EF method involves a methodical search for the optimal basis set that yields the absolute minima of the occupied energies, as required by density functional theory (DFT). Our calculated, indirect band gap of 6.91eV, from towards the L point, is in excellent agreement with experimental value of 6.93-7.7eV, at room temperature (RT). We have also calculated the total (DOS) and partial (pDOS) densities of states as well as the bulk modulus. Our calculated bulk modulus is in excellent agreement with experiment. Work funded in part by the US Department of Energy (DOE), National Nuclear Security Administration (NNSA) (Award No.DE-NA0002630), the National Science Foundation (NSF) (Award No, 1503226), LaSPACE, and LONI-SUBR.
Ab-initio Calculations of Accurate Electronic Properties of Wurzite AlN
Nwigboji, Ifeanyi; Malozovsky, Yuriy; Bagayoko, Diola; Bagayoko Research Group Team
2014-03-01
We present results from ab-initio, self consistent local density approximation (LDA) calculations of electronic and related properties of wurtzite Aluminum Nitride (w-AlN). Our non-relativistic computations employed the Ceperley and Alder LDA potential and the linear combination of atomic orbital (LCAO) formalism. The implementation of the LCAO formalism followed the Bagayoko, Zhao, and Williams' method as enhanced by Ekuma and Franklin (BZW-EF). The BZW-EF method verifiably obtains the minima of the occupied energies; these minima provide the most variationally and physically valid density functional theory (DFT) description of the ground states of materials under study. Our preliminary results for w-AlN show that w-AlN has a direct band gap of 5.82 eV at the Γ point. The preliminary energy bands were obtained with a basis set comprising 48 functions. None of the several, larger basis sets tested to date led to occupied energies lower than those obtained with the above 48. While most previous LDA calculations are 2 eV smaller or more than the experimental value of 5.9 eV that is in excellent agreement with our finding, considering the typical experimental uncertainty of 0.2 eV for absorption measurements on AlN. We also discuss our calculated density of states (DOS) and partial densities of states (pDOS).
Mateus, Margarida P. S.; Cabral, Benedito J. C.
2007-11-01
Theoretical calculations for the electron binding energies (EBEs) of several organic azides including hydrazoic acid, methyl azide, ethyl azide, 2-chloroethyl azide, 2-azidoethanol, azidoacetone, 2-azidoacetic acid, 3-azido-2-butanone, and 2-azidoethyl acetate are reported. EBEs were calculated with ab initio Green's function (GF) and density functional theory (DFT). Complete basis-set extrapolated coupled cluster calculations with single, double, and perturbative triple excitations [CCSD(T)] for the first ionization energy of azides are also reported. It is shown that EBEs from GF and DFT calculations are in better agreement with experiment than Hartree-Fock predictions.
Energy Technology Data Exchange (ETDEWEB)
Borges, P. D., E-mail: pdborges@gmail.com, E-mail: lscolfaro@txstate.edu; Scolfaro, L., E-mail: pdborges@gmail.com, E-mail: lscolfaro@txstate.edu [Department of Physics, Texas State University, San Marcos, Texas 78666 (United States)
2014-12-14
The thermoelectric properties of indium nitride in the most stable wurtzite phase (w-InN) as a function of electron and hole concentrations and temperature were studied by solving the semiclassical Boltzmann transport equations in conjunction with ab initio electronic structure calculations, within Density Functional Theory. Based on maximally localized Wannier function basis set and the ab initio band energies, results for the Seebeck coefficient are presented and compared with available experimental data for n-type as well as p-type systems. Also, theoretical results for electric conductivity and power factor are presented. Most cases showed good agreement between the calculated properties and experimental data for w-InN unintentionally and p-type doped with magnesium. Our predictions for temperature and concentration dependences of electrical conductivity and power factor revealed a promising use of InN for intermediate and high temperature thermoelectric applications. The rigid band approach and constant scattering time approximation were utilized in the calculations.
Persistent current of relativistic electrons on a Dirac ring in presence of impurities
Ghosh, Sumit
2014-08-01
We study the behaviour of persistent current of relativistic electrons on a one dimensional ring in presence of attractive/repulsive scattering potentials. In particular, we investigate the persistent current in accordance with the strength as well as the number of the scattering potential. We find that in presence of single scatterer the persistent current becomes smaller in magnitude than the scattering free scenario. This behaviour is similar to the non-relativistic case. Even for a very strong scattering potential, finite amount of persistent current remains for a relativistic ring. In presence of multiple scatterer we observe that the persistent current is maximum when the scatterers are placed uniformly compared to the current averaged over random configurations. However if we increase the number of scatterers, we find that the random averaged current increases with the number of scatterers. The latter behaviour is in contrast to the non-relativistic case. © 2014 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.
International Nuclear Information System (INIS)
Nakatsuji, H.
1979-01-01
The solutions of the SAC (symmetry-adapated-cluster) and SAC CI theories for the study of electron correlations in ground and excited states, respectively have been summarized. Variational and non-variational solutions are considered for both theories and their features are discussed. (Auth.)
Ab initio electron propagator theory of molecular wires. II. Multiorbital terminal description.
Dahnovsky, Yu; Ortiz, J V
2006-04-14
Correlated, ab initio electron propagator methodology may be applied to the calculation of electrical current through a molecular wire. A new theoretical formalism is developed for the calculation of retarded and advanced Green functions in terms of the electron propagator matrix for a bridge molecule. The calculation of the current requires integration in a complex half-plane for a trace that involves terminal and Green function matrices that may have any rank. Because the latter arrays have poles represented by matrices, an alternative expression is developed in terms of ordinary poles which are (n-1)-fold degenerate or nondegenerate. For an arbitrary number of terminal orbitals, the analytical expression for the current is given in terms of pole strengths, poles, and terminal matrix elements of the electron propagator, i.e., the parameters that are found in the output of numerical calculations.
Density-functional theory for f-electron systems. The α-γ phase transition in cerium
International Nuclear Information System (INIS)
Casadei, Marco
2013-01-01
Rare earths are technologically important and scientifically highly interesting elements. The description of the volume collapse exhibited by some rare earth metals poses a great challenge to density-functional theory (DFT) since local/semi-local functionals (LDA/GGA) only partially capture the associated phase transitions. In this work this problem is approached by treating all electrons at the same quantum mechanical level, using both hybrid functionals (e.g. PBE0 and HSE06) and exact-exchange plus correlation in the random-phase approximation (EX+cRPA). The performance of recently developed beyond RPA schemes is also assessed. The isostructural α-γ phase transition in cerium is the most studied. The exact exchange contribution in PBE0 and HSE06 is crucial to produce two distinct solutions that can be associated with the α and γ phases. The two solutions emerge in bulk as well as in cluster calculations. Most notable is their presence in the cerium dimer. However, quantitative agreement with the extrapolated phase diagram requires EX+cRPA. So far the EX+cRPA correction can only be applied to cerium clusters and not to the bulk. A cluster of 19 atoms cut from the fcc crystal structure (the same that characterizes the α and γ phases) was therefore determined as representative. (EX+cRPA) rate at PBE0 for Ce 19 provides good agreement with the extrapolated transition pressure to zero temperature. We predict that a pressure induced phase transition should exist at or close to zero. A finite temperature phase diagram can be drawn in reasonable agreement with experiment by adding entropic effects. The cerium neighbors are also studied: lanthanum, which has no f electrons, praseodymium, with three f electrons and a volume collapse, and neodymium, with four f electrons and no volume collapse. Multiple solutions are also present for these f electron elements, confirming the importance of exact-exchange for f electron systems.
International Nuclear Information System (INIS)
Moranchel y Rodriguez, M.; Alvarez R, J.T.
2007-01-01
The definition of the spectral fluence of the electrons used in the Spencer deduction for the Bragg-Gray cavity theory (BG) it assumes the additional condition of electronic equilibrium (EE). Such condition leaves to that the absorbed doses ratio of the means regarding that of the cavity is expressed in function of the total mass stopping power of the means. In this work it is shown that, more that the total mass stopping power should be in function of the collisional mass stopping power of the means, in accordance with the assumed EE condition. As consequence, an expression is obtained for this absorbed dose ratio that it depends exclusively on the collisional mass stopping powers of both means, being a more representative expression of the physical phenomena that happen. Also, an expression for the primary electrons spectral fluence is obtained reflecting thoroughly the physical processes that will give origin to the absorbed dose in the means. Finally, an additional condition for the existence of the EE in function of the fraction of the energy lost by the electrons in the stopping radiation. (Author)
Elements of non-relativistic quantum mechanics
Sobrino, Luis
1996-01-01
This book presents the basic structure of quantum mechanics, the elements needed to properly understand the subject and its applications. It is written at a level which is intermediate between the standard graduate textbooks, which it intends to supplement, and the more advanced mathematical writings in the subject. Particular attention is given to the concepts of kinematical and dynamical symmetries. The unifying thread that links the study of particles and systems of particles is the connection between Galilean invariance and the fundamental observables of a system. The mathematical appendic
Energy Technology Data Exchange (ETDEWEB)
Gamble, John King [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nielsen, Erik [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Baczewski, Andrew David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moussa, Jonathan Edward [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gao, Xujiao [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Salinger, Andrew G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Muller, Richard P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2017-07-01
This paper describes our work over the past few years to use tools from quantum chemistry to describe electronic structure of nanoelectronic devices. These devices, dubbed "artificial atoms", comprise a few electrons, con ned by semiconductor heterostructures, impurities, and patterned electrodes, and are of intense interest due to potential applications in quantum information processing, quantum sensing, and extreme-scale classical logic. We detail two approaches we have employed: nite-element and Gaussian basis sets, exploring the interesting complications that arise when techniques that were intended to apply to atomic systems are instead used for artificial, solid-state devices.
Energy Technology Data Exchange (ETDEWEB)
Nordlund, Dennis; Odelius, Michael; Bluhm, Hendrik; Ogasawara, Hirohito; Pettersson, Lars G.M.; Nilsson, Anders
2008-04-29
We present valence photoelectron emission spectra of liquid water in comparison with gas-phase water, ice close to the melting point, low temperature amorphous and crystalline ice. All aggregation states have major electronic structure changes relative to the free molecule, with rehybridization and development of bonding and anti-bonding states accompanying the hydrogen bond formation. Sensitivity to the local structural order, most prominent in the shape and splitting of the occupied 3a{sub 1} orbital, is understood from the electronic structure averaging over various geometrical structures, and reflects the local nature of the orbital interaction.
Sturmian theory of electron energy distributions in low energy ion-atom collisions
Energy Technology Data Exchange (ETDEWEB)
Ovchinnikov, S.Yu. [Department of Physics and Astronomy, University of Tennessee, 401 Nielsen Physics Building, Knoxville, TN 37996-1200 (United States) and Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States)]. E-mail: serge@charcoal.phys.utk.edu; Macek, J.H. [Department of Physics and Astronomy, University of Tennessee, 401 Nielsen Physics Building, Knoxville, TN 37996-1200 (United States); Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States)
2005-12-15
The energy and angular distributions of electrons ejected from targets and projectiles in the collisions of slow H and H{sup -} with He targets has been calculated exactly in a model that treats electron interactions with neutral targets via zero-range interactions. These calculations employ two-center Sturmian functions for collisions at non-zero impact parameters. The computed distributions are compared with recent measurements for He targets. Total ionization cross sections are also computed and compared with experiment over a broad energy range for proton, alpha particle and neutral hydrogen impact on helium atoms. The calculations are in generally good agreement with experiment.
International Nuclear Information System (INIS)
Lazaros, Avrilios
2000-01-01
The interaction of ECRH with the m/n=2/1 tearing mode, which was observed in toroidal plasmas, is attributed to the superthermal electrons which are produced on the EC resonance by the ECRH. Superthermal electrons diffusing across the q=2 surface, exchange power with the m/n=2/1 MHD mode which is either suppressed or enhanced. When the EC resonance is outside the rational surface, the mode is always suppressed. When the EC resonance is inside the rational surface, modes with large amplitude are enhanced while modes with small amplitude are suppressed. (author)
Zheng, Ming; Chen, Fang-Yuan; Tian, Jia-Nan; Pan, Qing-Jiang
2018-03-21
To provide deep insight into cation-cation interactions (CCIs) involving hexavalent actinyl species that are major components in spent nuclear fuel and pose important implications for the effective removal of radiotoxic pollutants in the environment, a series of homo- and heterobimetallic actinide complexes supported by cyclopentadienyl (Cp) and polypyrrolic macrocycle (H 4 L) ligands were systematically investigated using relativistic density functional theory. The metal sort in both parts of (THF)(H 2 L)(OAn VI O) and (An') III Cp 3 from U to Np to Pu, as well as the substituent bonding to Cp from electron-donating Me to H to electron-withdrawing Cl, SiH 3 , and SiMe 3 , was changed. Over 0.70 electrons are unraveled to transfer from the electron-rich U III to the electron-deficient An VI of the actinyl moiety, leading to a more stable An V -U IV isomer; in contrast, uranylneptunium and uranylplutonium complexes behave as electron-resonance structures between VI-III and V-IV. These were further corroborated by geometrical and electronic structures. The energies of CCIs (i.e., O exo -An' bonds) were calculated to be -19.6 to -41.2 kcal/mol, affording those of OUO-Np (-23.9 kcal/mol) and OUO-Pu (-19.6 kcal/mol) with less electron transfer (ET) right at the low limit. Topological analyses of the electron density at the O exo -An' bond critical points demonstrate that the CCIs are ET or dative bonds in nature. A positive correlation has been built between the CCIs' strength and corresponding ET amount. It is concluded that the CCIs of O exo -An' are driven by the electrostatic attraction between the actinyl oxo atom (negative) and the actinide ion (positive) and enhanced by their ET. Finally, experimental syntheses of (THF)(H 2 L)(OU VI O)(An') III Cp 3 (An' = U and Np) were well reproduced by thermodynamic calculations that yielded negative free energies in a tetrahydrofuran solution but a positive one for their uranylplutonium analogue, which was synthetically
Features of projectile motion in the special theory of relativity
International Nuclear Information System (INIS)
Shahin, Ghassan Y
2006-01-01
A relativistic projectile motion in a vacuum is examined by means of elementary consequences of special relativity. Exact analytical expressions were found for the kinematics variables using basic mathematical tools. The trajectory equation was established and the area under the trajectory traversed by the relativistic projectile was determined. It was found that, unlike non-relativistic projectile motion, the launching angles that maximize both the horizontal range as well as the area under the trajectory are functions of the initial speed. It is anticipated that this paper will be consistent with the intuition of students and serve as a resource for further problems usually encountered in the special theory of relativity
Moment techniques in atomic and molecular scattering theory
International Nuclear Information System (INIS)
Reinhardt, W.P.
1980-01-01
Moment techniques have recently been shown to be useful in ab initio calculation of atomic and molecular continuum processes. We illustrate these methods in a discussion of the photoeffect in hydrogen (H) and H - , and in a discussion of e + -H scattering. As further illustrations of the utility of moments in non-relativistic scattering we consider their use in extracting information from classical trajectory treatments of molecular collisions, and their phenomenological application in correlating experimental data via the information theory approach of Bernstein and Levine
Asymmetric nuclear matter and neutron star properties within the extended Brueckner theory
Energy Technology Data Exchange (ETDEWEB)
Hassaneen, Khaled S.A. [Sohag University, Physics Department, Faculty of Science, Sohag (Egypt); Taif University, Physics Department, Faculty of Science, Taif (Saudi Arabia)
2017-01-15
Microscopically, the equation of state (EOS) and other properties of asymmetric nuclear matter at zero temperature have been investigated extensively by adopting the non-relativistic Brueckner-Hartree-Fock (BHF) and the extended BHF approaches by using the self-consistent Green's function approach or by including a phenomenological three-body force. Once three-body forces are introduced, the phenomenological saturation point is reproduced and the theory is applied to the study of neutron star properties. We can calculate the total mass and radius for neutron stars using various equations of state at high densities in β-equilibrium without hyperons. A comparison with other microscopic predictions based on non-relativistic and density-dependent relativistic mean-field calculations has been done. It is found that relativistic EOS yields however larger mass and radius for neutron star than predictions based on non-relativistic approaches. Also the three-body force plays a crucial role to deduce the theoretical value of the maximum mass of neutron stars in agreement with recent measurements of the neutron star mass. (orig.)
[Theory of exotic superconducting and normal states of heavy electron and high Tc materials
International Nuclear Information System (INIS)
1990-01-01
This paper discusses: quadrupole Kondo effect; heavy electron transport properties; quadrupolar fluctuation mechanism for high-T c superconductors; research accomplishments for the t--J model of high-T c superconductors; interpretation of high-T c superconductors experimental data; and dynamics of strongly correlated systems
von Cosel, Jan; Cerezo, Javier; Kern-Michler, Daniela; Neumann, Carsten; van Wilderen, Luuk J. G. W.; Bredenbeck, Jens; Santoro, Fabrizio; Burghardt, Irene
2017-10-01
Vibrationally resolved electronic absorption spectra including the effect of vibrational pre-excitation are computed in order to interpret and predict vibronic transitions that are probed in the Vibrationally Promoted Electronic Resonance (VIPER) experiment [L. J. G. W. van Wilderen et al., Angew. Chem., Int. Ed. 53, 2667 (2014)]. To this end, we employ time-independent and time-dependent methods based on the evaluation of Franck-Condon overlap integrals and Fourier transformation of time-domain wavepacket autocorrelation functions, respectively. The time-independent approach uses a generalized version of the FCclasses method [F. Santoro et al., J. Chem. Phys. 126, 084509 (2007)]. In the time-dependent approach, autocorrelation functions are obtained by wavepacket propagation and by the evaluation of analytic expressions, within the harmonic approximation including Duschinsky rotation effects. For several medium-sized polyatomic systems, it is shown that selective pre-excitation of particular vibrational modes leads to a redshift of the low-frequency edge of the electronic absorption spectrum, which is a prerequisite for the VIPER experiment. This effect is typically most pronounced upon excitation of modes that are significantly displaced during the electronic transition, such as ring distortion modes within an aromatic π-system. Theoretical predictions as to which modes show the strongest VIPER effect are found to be in excellent agreement with experiment.
On the estimation of emissivity of metals within the framework of electron classical theory
International Nuclear Information System (INIS)
Shvarev, K.M.; Baum, B.A.
1978-01-01
The well-known Hagen-Rubens and Ashkinass-Foot equations used for calculating the spectral and integral emissive powers of metals usually yield enhanced values of optical characteristics. Improved formulas for estimating emissive characteristics of metals from their electric conductivity are obtained with an allowance for the relaxation time and in the free-electron model approximation
Hybrid theory calculation of electron-N2 scattering at 5 and 10 eV
Chandra, N.; Temkin, A.
1976-01-01
Hybrid theory results pertaining to e-N2 scattering have been evaluated for differential elastic and first vibrational excitation cross sections at 5 and 10 eV. Comparison with the recent experiment of Chutjian, Srivastava, and Trajmar is good (1976), although there is an indication that the calculated nonresonant (adiabatic-nuclei) contribution is somewhat too small. A short discussion engendered by this point is given.
Energy Technology Data Exchange (ETDEWEB)
Tur, A.; Fruit, G.; Louarn, P. [Institut de Recherche en Astrophysique et Planétologie (IRAP), CNRS UMR5277/Université Paul Sabatier, Toulouse (France); Yanovsky, V. [Institute for Single Crystals, National Academy of Sciences of Ukraine, Kharkov 61001 (Ukraine)
2014-03-15
In the general context of understanding the possible destabilization of a current sheet with applications to magnetospheric substorms or solar flares, a kinetic model is proposed for studying the resonant interaction between electromagnetic fluctuations and trapped bouncing electrons in a 2D current sheet. Tur et al. [A. Tur et al., Phys. Plasmas 17, 102905 (2010)] and Fruit et al. [G. Fruit et al., Phys. Plasmas 20, 022113 (2013)] already used this model to investigate the possibilities of electrostatic instabilities. Here, the model is completed for full electromagnetic perturbations. Starting with a modified Harris sheet as equilibrium state, the linearized gyrokinetic Vlasov equation is solved for electromagnetic fluctuations with period of the order of the electron bounce period. The particle motion is restricted to its first Fourier component along the magnetic field and this allows the complete time integration of the non local perturbed distribution functions. The dispersion relation for electromagnetic modes is finally obtained through the quasineutrality condition and the Ampere's law for the current density. It is found that for mildly strechted current, undamped modes oscillate at typical electron bounce frequency with wavelength of the order of the plasma sheet half thickness. As the stretching of the plasma sheet becomes more intense, the frequency of these normal modes decreases and beyond a certain threshold in ε = B{sub z}/B{sub lobes}, the mode becomes explosive with typical growth rate of a few tens of seconds. The free energy contained in the bouncing motion of the electrons may trigger an electromagnetic instability able to disrupt the cross-tail current in a few seconds. This new instability–electromagnetic electron-bounce instability–may explain fast and global scale destabilization of current sheets as required to describe substorm phenomena.
Energy Technology Data Exchange (ETDEWEB)
Brics, Martins; Kapoor, Varun; Bauer, Dieter [Institut fuer Physik, Universitaet Rostock, 18051 Rostock (Germany)
2013-07-01
Time-dependent density functional theory (TDDFT) with known and practicable exchange-correlation potentials does not capture highly correlated electron dynamics such as single-photon double ionization, autoionization, or nonsequential ionization. Time-dependent reduced density matrix functional theory (TDRDMFT) may remedy these problems. The key ingredients in TDRDMFT are the natural orbitals (NOs), i.e., the eigenfunctions of the one-body reduced density matrix (1-RDM), and the occupation numbers (OCs), i.e., the respective eigenvalues. The two-body reduced density matrix (2-RDM) is then expanded in NOs, and equations of motion for the NOs can be derived. If the expansion coefficients of the 2-RDM were known exactly, the problem at hand would be solved. In practice, approximations have to be made. We study the prospects of TDRDMFT following a top-down approach. We solve the exact two-electron time-dependent Schroedinger equation for a model Helium atom in intense laser fields in order to study highly correlated phenomena such as the population of autoionizing states or single-photon double ionization. From the exact wave function we calculate the exact NOs, OCs, the exact expansion coefficients of the 2-RDM, and the exact potentials in the equations of motion. In that way we can identify how many NOs and which level of approximations are necessary to capture such phenomena.
DEFF Research Database (Denmark)
Miyagi, Haruhide; Madsen, Lars Bojer
We have developed a new theoretical framework for time-dependent many-electron problems named time-dependent restricted-active-space self-consistent field (TD-RASSCF) theory. The theory generalizes the multicongurational time-dependent Hartree-Fock (MCTDHF) theory by truncating the expansion...... at a specific excitation level. In a numerical application to laser-driven electron dynamics of the one-dimensional beryllium atom, the TD-RASSCF method performs accurately while largely reducing the computational complexity compared to the MCTDHF method....
International Nuclear Information System (INIS)
Faisal, F H M
2009-01-01
In this communication, a four-component Dirac theory of ionization of a hydrogen molecular ion, H + 2 , in a super-intense laser field is presented. Analytic expressions for the spin-specific as well as the total ionization currents emitted from the ground state of the ion are derived. The results are given for arbitrary intensity, frequency, wavenumber and polarization of the field, and for the up or down spin of the bound and ionized states of the electron. They also apply for the case of inner-shell ionization of analogous heavier diatomic molecular ions. The presence of molecular two-slit interference effect, first found in the non-relativistic case, the spin-flip ionization current, and an asymmetry of the up- and down-spin currents similar to that predicted in the atomic case, is found to hold for the present relativistic molecular ionic case as well. The possibility of controlling the spin of the dominant ionization current in any direction by simply selecting the handedness of a circularly polarized incident laser field is pointed out. Finally, we note that the present results obtained within the strong field 'KFR' ansatz open up the way for an analogous fully relativistic four-component treatment for ionization of polyatomic molecules and clusters in super-intense laser fields. (fast track communication)
International Nuclear Information System (INIS)
Do, Van-Nam
2014-01-01
We review fundamental aspects of the non-equilibrium Green function method in the simulation of nanometer electronic devices. The method is implemented into our recently developed computer package OPEDEVS to investigate transport properties of electrons in nano-scale devices and low-dimensional materials. Concretely, we present the definition of the four real-time Green functions, the retarded, advanced, lesser and greater functions. Basic relations among these functions and their equations of motion are also presented in detail as the basis for the performance of analytical and numerical calculations. In particular, we review in detail two recursive algorithms, which are implemented in OPEDEVS to solve the Green functions defined in finite-size opened systems and in the surface layer of semi-infinite homogeneous ones. Operation of the package is then illustrated through the simulation of the transport characteristics of a typical semiconductor device structure, the resonant tunneling diodes. (review)
Close-coupling formalism for electron/positron-atom systems and underlying scattering theory
International Nuclear Information System (INIS)
Stelbovics, A.T.; Berge, L.
1996-01-01
The close-coupling method for electron/positron-atom scattering promises to give a complete description of the scattering process provided the space of target states is properly spanned. This paper will discuss the structure of the equations, emphasizing questions of stability associated with the expansions over sets of target states. For electron-atom scattering, the character of the solution is discussed and a simple example is given to illustrate the non-convergence of the half-shell T-matrix. This lack of convergence can be fixed by application of the symmetrisation boundary condition, leading to new forms of the equations. For positron atom scattering, the standard equations yield convergent half-shell T-matrices for all but the largest calculations. 17 refs., 3 tabs., 4 figs
A massively-parallel electronic-structure calculations based on real-space density functional theory
International Nuclear Information System (INIS)
Iwata, Jun-Ichi; Takahashi, Daisuke; Oshiyama, Atsushi; Boku, Taisuke; Shiraishi, Kenji; Okada, Susumu; Yabana, Kazuhiro
2010-01-01
Based on the real-space finite-difference method, we have developed a first-principles density functional program that efficiently performs large-scale calculations on massively-parallel computers. In addition to efficient parallel implementation, we also implemented several computational improvements, substantially reducing the computational costs of O(N 3 ) operations such as the Gram-Schmidt procedure and subspace diagonalization. Using the program on a massively-parallel computer cluster with a theoretical peak performance of several TFLOPS, we perform electronic-structure calculations for a system consisting of over 10,000 Si atoms, and obtain a self-consistent electronic-structure in a few hundred hours. We analyze in detail the costs of the program in terms of computation and of inter-node communications to clarify the efficiency, the applicability, and the possibility for further improvements.
Electron-optical metrology with femtosecond time resolution (theory and experiment)
Energy Technology Data Exchange (ETDEWEB)
Andreev, S V; Vorob' ev, Nikolai S; Greenfield, D E; Lozovoi, V I; Monastyrskii, M A; Serdyuchenko, Yu N; Smirnov, A V; Shchelev, Mikhail Ya [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
2013-04-30
The principles of simultaneous spatial and temporal focusing of photoelectron beams in nonstationary electric fields are theoretically studied and experimentally realised as applied to time-analysing image-converter tubes (ICTs). It is theoretically shown that the use of nonstationary focusing electric fields makes it possible to surpass the theoretical time resolution limit of ICTs (10{sup -4} s) determined for stationary fields by Zavoisky and Fanchenko in the 40s-50s of the last century. The possibility of forming electron packets with an energy of 10-30 KeV and a subfemtosecond duration (below 10{sup -15} s) gives impetus to the development of time-resolved electron diffraction, which is a direct method of investigation of atomic-molecular dynamics in solid and gaseous media. (extreme light fields and their applications)
Electronic, magnetic and mechanical properties of (Fe,Ni)2Nb from density functional theory
Qi, J. J.; Zhou, Y.; Wang, W.; Qian, L. H.; Lv, Z. Q.; Fu, W. T.
2018-04-01
A comprehensive analysis of the phase stability, electronic structure, magnetic and mechanical properties of the Laves phases Fe2Nb and Ni2Nb with C14, C15 and C36 structures has been presented using first-principles calculations. The effects of pressure on the formation energy and magnetic properties of Fe2Nb and Ni2Nb have been discussed. The effects of the composition on the mechanical properties of (Fe,Ni)2Nb have also been discussed. The results show that the electrons in Fe2Nb transfer from Fe to Nb, while the electrons shift from Nb to Ni in Ni2Nb. Fe2Nb and Ni2Nb with C14, C15 and C36 structure are of strong metallicity, and the metallicity of C15 phase is stronger than that of C14 and C36 types. The magnetic moments of Fe2Nb are similar to each other, and the value of C14-Fe2Nb is little bigger than that of the two others. The magnetic moments of Fe2Nb decrease with increasing pressure and the values decline evidently from 0 to 20 GPa. The hardness of C15 phase, with stronger metallicity, is lower than that of C14 phase and C36 phase. For (Fe,Ni)2Nb, the hardness decreases with increasing Ni and the ability to resist deformation increases with decreasing Ni.
Distorted-wave theory of electron-ion collisions. I. Direct excitation and ionization
International Nuclear Information System (INIS)
Hahn, Y.
1977-01-01
A simple modification of the Bethe approximation for high-energy electron-atom collisions is considered for the purpose of analyzing the medium-energy scattering by highly stripped ionic targets. The effect of amplitude and phase distortions of the projectile-electron wave function on the excitation and ionization cross sections is approximately taken into account using the Elwert factor and the eikonal procedure, respectively. To facilitate the cross-section calculation further, the momentum-transfer-dependent part in the excitation matrix element is factored out in terms of an average transfer. The energy dependence of the various modification factors is studied in detail, showing that the distortion effect is large for ionic targets and decays only slowly with the scattering energy, as E/sup -1/2/. For a neutral target, however, the distortion effects roughly cancel with each other, thus resulting in the effectiveness of the unmodified Bethe cross section at much lower energies than one usually expects. The improved formalism is applied to estimate the total cross sections for the direct excitation and ionization of outer-shell electrons of the ionic target. The results are drastically changed from the unmodified Bethe approximation, and are generally in fair agreement with experimental data for all energies except in the threshold region
International Nuclear Information System (INIS)
Rodionov, V.N.; Studenikin, A.I.
1985-01-01
Consideration of processes with the assistance of virtual and real Higgs scalar neutral σ-bosons in the presence of a constant external crossed electromagnetic field is conducted. In the second order of the perturbation theory in the Weinberg-Jalam model corresponding contribution into mass lepton operator in this base probability dependence of σ-boson emission and radiation field σ-bosn effects on the crossed field parameter is investigated: x=√(eFsub(μν)psup(ν)sup(2)/msup(3)
Abdelsalam, Hazem; Elhaes, Hanan; Ibrahim, Medhat A.
2018-03-01
The energy gap and dipole moment of chemically functionalized graphene quantum dots are investigated by density functional theory. The energy gap can be tuned through edge passivation by different elements or groups. Edge passivation by oxygen considerably decreases the energy gap in hexagonal nanodots. Edge states in triangular quantum dots can also be manipulated by passivation with fluorine. The dipole moment depends on: (a) shape and edge termination of the quantum dot, (b) attached group, and (c) position to which the groups are attached. Depending on the position of attached groups, the total dipole can be increased, decreased, or eliminated.
Berski, Slawomir; Sensato, Fabrício R; Polo, Victor; Andrés, Juan; Safont, V S
2011-02-03
The oxygen atom transfer reaction from the Mimoun-type complex MoO(η(2)-O(2))(2)OPH(3) to ethylene C(2)H(4) affording oxirane C(2)H(4)O has been investigated within the framework of the Bonding Evolution Theory in which the corresponding molecular mechanism is characterized by the topological analysis of the electron localization function (ELF) and Thom's catastrophe theory (CT). Topological analysis of ELF and electron density analysis reveals that all Mo-O bonds in MoO(η(2)-O(2))(2)OPH(3) and MoO(2)(η(2)-O(2))OPH(3) belong to closed-shell type interactions though negative values of total energy densities E(e)(r(BCP)) imply some covalent contribution. The peroxo O(i)-O(j) bonds are characterized as charge-shift or protocovalent species in which pairs of monosynaptic basins V(3)(O(i)), V(3)(O(j)) with a small electron population of ~0.25e each, are localized between core basins C(O(i)), C(O(j)). The oxygen transfer reaction from molybdenum diperoxo complex MoO(η(2)-O(2))(2)OPH(3) to C(2)H(4) system can be described by the following consecutive chemical events: (a) protocovalent peroxo O(2)-O(1) bond breaking, (b) reduction of the double C(1)=C(2) bond to single C(1)-C(2) bond in ethylene, (c) displacement of oxygen O(1) with two nonbonding basins, V(i=1,2)(O(1)), (d) increase of a number of the nonbonding basins to three (V(i=1,2,4)(O(1))); (e) reorganization and reduction in the number of nonbonding basis to two basins (V(i=1,4)(O(1))) resembling the ELF-topology of the nonbonding electron density in oxirane, (e) formation of the first O(1)-C(2) bond in oxirane, (f) C(2)-O(1)-C(2) ring closure, (g) formation of singular nonbonding basin V(O(2)) in new Mo=O(2) bond. The oxygen atom is transferred as an anionic moiety carrying a rather small electronic charge ranging from 0.5 to 0.7e.
Duffy, Patrick; Chong, Delano P.; Dupuis, Michel
1995-02-01
Density functional theory (DFT) is a field enjoying a tremendous recent surge in popularity among theoretical and practical chemists alike because of its ability to more easily handle larger molecular systems than conventional ab initio methods. Until recently, however, assessment of the quality of the properties predicted (and therefore the charge density) from DFT had been limited mainly to dipole moments and their nuclear coordinate and electric field derivatives. This paper presents the calculated results for some of the one-electron properties of the eight small molecules (NH3, PH3, H2O, H2S, HF, HCl, CO, and N2). The properties chosen weight different regions of the charge density, from either very close in or at the nucleus (e.g., δ, the electron density at the nucleus) to regions farther out from the nucleus (e.g., the diamagnetic susceptibility ). It is found that properties which depend on an accurate knowledge of the electron density near to the nucleus are predicted poorly by the local density approximation (LDA), while others more dependent on the charge density farther out from the nucleus are predicted much more accurately, possibly due to cancellation of errors. Use of the LDA is therefore not recommended for ``tight'' properties; use of a functional employing gradient corrections would be more suitable for this purpose.
Czekaj, I.; Witko, M.; Hermann, K.
2003-02-01
Electronic properties of the V 2O 3(0001) surface are studied using ab initio density functional theory method. In addition, the nature of surface V-O bonding as well as the electronic states of the structurally different surface oxygen and vanadium sites are discussed and compared with bulk oxygen/vanadium centers. The (0001) surface of vanadium sesquioxide is modeled using clusters of different size where the three ideal bulk-terminated surfaces, denoted as VV 'O (terminated by a double layer of vanadium atoms), V 'OV (terminated by one layer of V atoms), and OVV ' (terminated by one layer of oxygen atoms), are considered. For these surface terminations electronic properties of various surface and bulk centers are discussed. The results confirm bonding in vanadium sesquioxide as a mixture of ionic and covalent characters. Further, charging of structurally non-equivalent surface vanadium and oxygen sites is found to increase with the corresponding coordination number. Large differences in charging between surface and bulk vanadium atoms are found. In addition, the strong interaction between neighboring vanadium ions are observed.
Espinosa-Torres, Néstor D.; la Luz, David Hernández-de; Flores-Gracia, José Francisco J.; Luna-López, José A.; Martínez-Juárez, Javier; Vázquez-Valerdi, Diana E.
2014-09-01
In systems in atomic scale and nanoscale such as clusters or agglomerates constituted by particles from a few to less than 100 atoms, quantum confinement effects are very important. Their optical and electronic properties are often dependent on the size of the systems and the way in which the atoms in these clusters are bonded. Generally, these nanostructures display optical and electronic properties significantly different to those found in corresponding bulk materials. Silicon agglomerates embedded in silicon rich oxide (SRO) films have optical properties, which have been reported to be directly dependent on silicon nanocrystal size. Furthermore, the room temperature photoluminescence (PL) of SRO has repeatedly generated a huge interest due to its possible applications in optoelectronic devices. However, a plausible emission mechanism has not been widely accepted in the scientific community. In this work, we present a short review about the experimental results on silicon nanoclusters in SRO considering different techniques of growth. We focus mainly on their size, Raman spectra, and photoluminescence spectra. With this as background, we employed the density functional theory with a functional B3LYP and a basis set 6-31G* to calculate the optical and electronic properties of clusters of silicon (constituted by 15 to 20 silicon atoms). With the theoretical calculation of the structural and optical properties of silicon clusters, it is possible to evaluate the contribution of silicon agglomerates in the luminescent emission mechanism, experimentally found in thin SRO films.
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.
Espinosa-Torres, Néstor D; la Luz, David Hernández-de; Flores-Gracia, José Francisco J; Luna-López, José A; Martínez-Juárez, Javier; Vázquez-Valerdi, Diana E
2014-01-01
In systems in atomic scale and nanoscale such as clusters or agglomerates constituted by particles from a few to less than 100 atoms, quantum confinement effects are very important. Their optical and electronic properties are often dependent on the size of the systems and the way in which the atoms in these clusters are bonded. Generally, these nanostructures display optical and electronic properties significantly different to those found in corresponding bulk materials. Silicon agglomerates embedded in silicon rich oxide (SRO) films have optical properties, which have been reported to be directly dependent on silicon nanocrystal size. Furthermore, the room temperature photoluminescence (PL) of SRO has repeatedly generated a huge interest due to its possible applications in optoelectronic devices. However, a plausible emission mechanism has not been widely accepted in the scientific community. In this work, we present a short review about the experimental results on silicon nanoclusters in SRO considering different techniques of growth. We focus mainly on their size, Raman spectra, and photoluminescence spectra. With this as background, we employed the density functional theory with a functional B3LYP and a basis set 6-31G* to calculate the optical and electronic properties of clusters of silicon (constituted by 15 to 20 silicon atoms). With the theoretical calculation of the structural and optical properties of silicon clusters, it is possible to evaluate the contribution of silicon agglomerates in the luminescent emission mechanism, experimentally found in thin SRO films.
Electronic structure modeling of InAs/GaSb superlattices with hybrid density functional theory
Energy Technology Data Exchange (ETDEWEB)
Garwood, Tristan [Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials; Modine, Normand A. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Krishna, S. [Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials
2016-12-18
The application of first-principles calculations holds promise for greatly improving our understanding of semiconductor superlattices. By developing a procedure to accurately predict band gaps using hybrid density functional theory, it lays the groundwork for future studies investigating more nuanced properties of these structures. Our approach allows a priori prediction of the properties of SLS structures using only the band gaps of the constituent materials. Furthermore, it should enable direct investigation of the effects of interface structure, e.g., intermixing or ordering at the interface, on SLS properties. In this paper, we present band gap data for various InAs/GaSb type-II superlattice structures calculated using the generalized Kohn-Sham formulation of density functional theory. A PBE0-type hybrid functional was used, and the portion of the exact exchange was tuned to fit the band gaps of the binary compounds InAs and GaSb with the best agreement to bulk experimental values obtained with 18% of the exact exchange. The heterostructures considered in this study are 6 monolayer (ML) InAs/6 ML GaSb, 8 ML InAs/8 ML GaSb and 10 ML InAs/10 ML GaSb with deviations from the experimental band gaps ranging from 3% to 11%.
Tateiwa, Naoyuki; Pospíšil, Jiří; Haga, Yoshinori; Sakai, Hironori; Matsuda, Tatsuma D.; Yamamoto, Etsuji
2017-07-01
We have carried out an analysis of magnetic data in 69 uranium, 7 neptunium, and 4 plutonium ferromagnets with the spin fluctuation theory developed by Takahashi [Y. Takahashi, J. Phys. Soc. Jpn. 55, 3553 (1986), 10.1143/JPSJ.55.3553]. The basic and spin fluctuation parameters of the actinide ferromagnets are determined and the applicability of the spin fluctuation theory to actinide 5 f system has been discussed. Itinerant ferromagnets of the 3 d transition metals and their intermetallics follow a generalized Rhodes-Wohlfarth relation between peff/ps and TC/T0 , viz., peff/ps∝(TC/T0) -3 /2 . Here, ps, peff, TC, and T0 are the spontaneous and effective magnetic moments, the Curie temperature, and the width of spin fluctuation spectrum in energy space, respectively. The same relation is satisfied for TC/T0uranium and neptunium ferromagnets below (TC/T0)kink=0.32 ±0.02 , where a kink structure appears in relation between the two quantities. ps increases more weakly above (TC/T0)kink. A possible interpretation with the TC/T0 dependence of ps is given.
Estimation of cluster stability using the theory of electron density functional
International Nuclear Information System (INIS)
Borisov, Yu.A.
1985-01-01
Prospects of using simple versions of the electron density functional for studying the energy characteristics of cluster compounds Was discussed. These types of cluster compounds were considered: clusters of Cs, Be, B, Sr, Cd, Sc, In, V, Tl, I elements as intermediate form between molecule and solid body, metalloorganic Mo, W, Tc, Re, Rn clusters and elementoorganic compounds of nido-cluster type. The problem concerning changes in the binding energy of homoatomic clusters depending on their size and three-dimensional structure was analysed
International Nuclear Information System (INIS)
Kazanskii, A.K.
1982-01-01
An exactly solvable model is constructed for the description of the processes that take place when a slow electron collides with a diatomic molecule (vibrational excitation, associative detachment, and dissociative attachment). As a particular model of the variant, the case of an antibonding (virtual) state of an intermediate state is considered, and a term of this state is parametrized in a very simple manner. The vibrational excitation and dissociative attachment are calculated for a system corresponding to the HCl molecule. The results are in good qualitative agreement with experiment
International Nuclear Information System (INIS)
Saievar, E.; Gharleghi, A.
2006-01-01
Doping Calcium in Lanthanum site of LaCrO 3 compound increasing the density of states in valance band and decreasing the band gap width because of increases of S electrons in valance band and variety of interaction energies from Cr +3 -Cr +4 couple in valance band. We have used Wien2k software for evaluating this mechanisms. Using of 0.25 percent of dopant and a kind of the space group of cell, let us to use one cell in calculations. We have used GGA approximation in this calculations.
Theory of Square-Wave Voltammetry of Two-Electron Reduction with the Adsorption of Intermediate
Directory of Open Access Journals (Sweden)
Milivoj Lovric
2012-01-01
Full Text Available Thermodynamically unstable intermediate of fast and reversible two-electron electrode reaction can be stabilized by the adsorption to the electrode surface. In square-wave voltammetry of this reaction mechanism, the split response may appear if the electrode surface is not completely covered by the adsorbed intermediate. The dependence of the difference between the net peak potentials of the prepeak and postpeak on the square-wave frequency is analyzed theoretically. This relationship can be used for the estimation of adsorption constant.
Gauge field theory approach to spin transport in a 2D electron gas
Directory of Open Access Journals (Sweden)
B. Berche
2009-01-01
Full Text Available We discuss the Pauli Hamiltonian including the spin-orbit interaction within an U(1×SU(2 gauge theory interpretation, where the gauge symmetry appears to be broken. This interpretation offers new insight into the problem of spin currents in the condensed matter environment, and can be extended to Rashba and Dresselhaus spin-orbit interactions. We present a few outcomes of the present formulation: i it automatically leads to zero spin conductivity, in contrast to predictions of Gauge symmetric treatments, ii a topological quantization condition leading to voltage quantization follows, and iii spin interferometers can be conceived in which, starting from an arbitrary incoming unpolarized spinor, it is always possible to construct a perfect spin filtering condition.
Tailoring of the electronic properties of ZnO-polyacrylonitrile nanofibers: Experiment and theory
International Nuclear Information System (INIS)
Iatsunskyi, Igor; Vasylenko, Andrij; Viter, Roman; Kempiński, Mateusz; Nowaczyk, Grzegosz; Jurga, Stefan; Bechelany, Mikhael
2017-01-01
Highlights: • ZnO-polyacrylonitrile (ZnO-PAN) nanofibers were obtained by electrospinning method and atomic layer deposition. • Relation between structural and electronic properties of ZnO-PAN nanofibers were established. • DFT for calculation of ZnO work function was performed. - Abstract: We report the study of ZnO-polyacrylonitrile (ZnO-PAN) nanofibers fabricated by the combination of electrospinning and atomic layer deposition. The latter technique enables us to control the size of the surface of ZnO 1D nanostructures and hence its effectiveness for energy and biosensor applications. We observe the tendency of ZnO to form nanograins with increase of the layer thickness, and investigate the influence of the grain size on the electronic properties of the nanofibers. It is demonstrated that the ZnO work function (Φ) is strongly affected by surface band bending in the ZnO layer. The observed change of Φ in ZnO layers results from the curvature of the grain surface as well as the presence of the hydroxyl and oxygen groups, adsorbed on ZnO surface and is in a good agreement with theoretical prediction.
Application of electron-beam ionized discharges to switches - a comparison of experiment with theory
International Nuclear Information System (INIS)
Hallada, M.R.; Bailey, W.F.; Bletzinger, P.
1982-01-01
A theoretical investigation of high-pressure discharges ionized by an external electron beam (e-beam) was conducted. Only when secondary emission from the cathode and electron-impact ionization of metastable states were included in the analysis did calculated current-voltage (I-V) characteristics for argon and methane discharges compare well with experimental data. The I-V characteristics obtained reveal a sharp rise in the current at a certain threshold voltage. This threshold voltage and the entire I-V characteristic are shifted to lower voltages when metastable ionization is significant. Below the threshold voltage and at low external ionization source strengths, a region of negative differential conductivity is obtained. In the high-current region, the I-V slope is controlled by the secondary emission coefficient. The additional cathode sheath ionization from secondary emission and ionization from metastable states significantly reduces the discharge voltage. This important effect can be used to reduce e-beam switch losses and increase lifetime through judicious gas mixture selection and proper cathode conditioning
Tailoring of the electronic properties of ZnO-polyacrylonitrile nanofibers: Experiment and theory
Energy Technology Data Exchange (ETDEWEB)
Iatsunskyi, Igor, E-mail: igoyat@amu.edu.pl [NanoBioMedical Centre, Adam Mickiewicz University in Poznan, Umultowska 85, 61-614, Poznan (Poland); Vasylenko, Andrij, E-mail: A.Vasylenko@warwick.ac.uk [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL (United Kingdom); Institute for Condensed Matter Physics NAS Ukraine, 1 Sventsitskogo str. 79011 Lviv (Ukraine); Viter, Roman, E-mail: roman.viter@lu.lv [Institute of Atomic Physics and Spectroscopy, University of Latvia, 19 Raina Blvd., LV 1586, Riga (Latvia); Kempiński, Mateusz; Nowaczyk, Grzegosz [NanoBioMedical Centre, Adam Mickiewicz University in Poznan, Umultowska 85, 61-614, Poznan (Poland); Jurga, Stefan [NanoBioMedical Centre, Adam Mickiewicz University in Poznan, Umultowska 85, 61-614, Poznan (Poland); Department of Macromolecular Physics, Adam Mickiewicz University, Umultowska, 85, 61-614 Poznan (Poland); Bechelany, Mikhael, E-mail: mikhael.bechelany@univ-montp2.fr [European Institute of Membranes (IEM, ENSCM-UM-CNRS, UMR 5635), University of Montpellier, Place Eugène Bataillon, F-34095, Montpellier (France)
2017-07-31
Highlights: • ZnO-polyacrylonitrile (ZnO-PAN) nanofibers were obtained by electrospinning method and atomic layer deposition. • Relation between structural and electronic properties of ZnO-PAN nanofibers were established. • DFT for calculation of ZnO work function was performed. - Abstract: We report the study of ZnO-polyacrylonitrile (ZnO-PAN) nanofibers fabricated by the combination of electrospinning and atomic layer deposition. The latter technique enables us to control the size of the surface of ZnO 1D nanostructures and hence its effectiveness for energy and biosensor applications. We observe the tendency of ZnO to form nanograins with increase of the layer thickness, and investigate the influence of the grain size on the electronic properties of the nanofibers. It is demonstrated that the ZnO work function (Φ) is strongly affected by surface band bending in the ZnO layer. The observed change of Φ in ZnO layers results from the curvature of the grain surface as well as the presence of the hydroxyl and oxygen groups, adsorbed on ZnO surface and is in a good agreement with theoretical prediction.
Density-Functional Theory description of transport in the single-electron transistor
Zawadzki, Krissia; Oliveira, Luiz N.
The Kondo effect governs the low-temperature transport properties of the single electron transistor (SET), a quantum dot bridging two electron gases. In the weak coupling limit, for odd dot occupation, the gate-potential profile of the conductance approaches a step, known as the Kondo plateau. The plateau and other SET properties being well understood on the basis of the Anderson model, more realistic (i. e., DFT) descriptions of the device are now desired. This poses a challenge, since the SET is strongly correlated. DFT computations that reproduce the conductance plateau have been reported, e. g., by, which rely on the exact functional provided by the Bethe-Ansatz solution for the Anderson model. Here, sticking to DFT tradition, we employ a functional derived from a homogeneous system: the parametrization of the Lieb-Wu solution for the Hubbard model due to. Our computations reproduce the plateau and yield other results in accurate agreement with the exact diagonalization of the Anderson Hamiltonian. The prospects for extensions to realistic descriptions of two-dimensional nanostructured devices will be discussed. Luiz N. Oliveira thanks CNPq (312658/2013-3) and Krissia Zawadzki thanks CNPq (140703/2014-4) for financial support.