Real and Hybrid Atomic Orbitals.
Cook, D. B.; Fowler, P. W.
1981-01-01
Demonstrates that the Schrodinger equation for the hydrogenlike atom separates in both spheroconal and prolate spheroidal coordinates and that these separations provide a sound theoretical basis for the real and hybrid atomic orbitals. (Author/SK)
The atomic orbitals of the topological atom.
Ramos-Cordoba, Eloy; Salvador, Pedro; Mayer, István
2013-06-07
The effective atomic orbitals have been realized in the framework of Bader's atoms in molecules theory for a general wavefunction. This formalism can be used to retrieve from any type of calculation a proper set of orthonormalized numerical atomic orbitals, with occupation numbers that sum up to the respective Quantum Theory of Atoms in Molecules (QTAIM) atomic populations. Experience shows that only a limited number of effective atomic orbitals exhibit significant occupation numbers. These correspond to atomic hybrids that closely resemble the core and valence shells of the atom. The occupation numbers of the remaining effective orbitals are almost negligible, except for atoms with hypervalent character. In addition, the molecular orbitals of a calculation can be exactly expressed as a linear combination of this orthonormalized set of numerical atomic orbitals, and the Mulliken population analysis carried out on this basis set exactly reproduces the original QTAIM atomic populations of the atoms. Approximate expansion of the molecular orbitals over a much reduced set of orthogonal atomic basis functions can also be accomplished to a very good accuracy with a singular value decomposition procedure.
HYBRID ORBITALS OF CARBON ATOMS IN THE D6hC36 MOLECULE UNDER THE ROTATING ELLIPSOID MODEL
Institute of Scientific and Technical Information of China (English)
Tong Guo-ping
2000-01-01
The hybrid orbitals of carbon atoms in the D6h C36 molecule arestudied using two rotating ellipsoid models. The model 1 is 1.66R for theshort semi-axis and 2.34R for the long semi-axis, and the model 2 is 1.78R and 2.26R respectively, where R is the C-C bond length. By comparison,we think the model 2 to be more proper in revealing the electronic properties of the D6h C36 molecule. The component of s orbitals in the states hybridized for each of the atoms is much larger than C60, in which the sorbit component is 0.0380 and the porbit is 0.9620. The most component is 0.2098and the least is 0.0482 for model 1; the most is 0.1764 and the least is0.0656 for model 2.
The Atomic orbitals of the topological atom
Ramos-Cordoba, Eloy; Salvador Sedano, Pedro
2013-01-01
The effective atomic orbitals have been realized in the framework of Bader's atoms in molecules theory for a general wavefunction. This formalism can be used to retrieve from any type of calculation a proper set of orthonormalized numerical atomic orbitals, with occupation numbers that sum up to the respective Quantum Theory of Atoms in Molecules (QTAIM) atomic populations. Experience shows that only a limited number of effective atomic orbitals exhibit significant occupation numbers. These c...
Duo, Shuwang; Song, Mimi; Liu, Tingzhi; Hu, Changyuan; Li, Meishuan
2013-02-01
A novel polyimide (PI) hybrid nanocomposite containing polyhedral oligomeric silsesquioxane (POSS) had been prepared by copolymerization of trisilanolphenyl-POSS, 4,4'-oxydianiline (ODA), and pyromellitic dianhydride (PMDA). The AO resistance of these PI/POSS hybrid films was tested in the ground-based AO simulation facility. Exposed and unexposed surfaces were characterized by SEM and X-ray photoelectron spectroscopy. SEM images showed that the surface of the 20 wt% PI/POSS became much less rough than that of the pristine polyimide. Mass measurements of the samples showed that the erosion yield of the PI/POSS (20 wt.%) hybrid film was 1.2 x 10(-25) cm3/atom, and reduced to 4% of the polyimide film. The XPS data indicated that the carbon content of the near-surface region was decreased from 60.1 to 13.2 at% after AO exposure. The oxygen and silicon concentrations in the near-surface region increased to 1.96 after AO exposure. The nanometer-sized structure of POSS, with its large surface area, had led AO-irradiated samples to form a SiO2 passivation layer, which protected the underlying polymer from further AO attack. The incorporation of POSS into the polyimide could dramatically improve the AO resistance of polyimide films in low earth orbit environment.
Energy Technology Data Exchange (ETDEWEB)
Yip, Frank L; McCurdy, C. William; Rescigno, Thomas N
2010-04-19
A general approach for ab initio calculations of electronic continuum processes is described in which the many-electron wave function is expanded using a combination of orbitals at short range and the finite-element discrete variable representation(FEM-DVR) at larger distances. The orbital portion of the basis allows the efficient construction of many-electron configurations in which some of the electrons are bound, but because the orbitals are constructed from an underlying FEM-DVR grid, the calculation of two-electron integrals retains the efficiency of the primitive FEM-DVR approach. As an example, double photoionization of beryllium is treated in a calculation in which the 1s{sup 2} core is frozen. This approach extends the use of exterior complex scaling (ECS) successfully applied to helium and H{sub 2} to calculations with two active electrons on more complicated targets. Integrated, energy-differential and triply-differential cross sections are exhibited, and the results agree well with other theoretical investigations.
Epov, Vladimir N
2011-08-07
A novel approach is suggested to investigate the mechanisms of chemical complexation reactions based on the results of Fujii with co-workers; they have experimentally observed that several metals and metalloids demonstrate mass-independent isotope fractionation during the reactions with the DC18C6 crown ether using solvent-solvent extraction. In this manuscript, the isotope fractionation caused by the magnetic isotope effect is used to understand the mechanisms of chemical exchange reactions. Due to the rule that reactions are allowed for certain electron spin states, and forbidden for others, magnetic isotopes show chemical anomalies during these reactions. Mass-independent fractionation is suggested to take place due to the hyperfine interaction of the nuclear spin with the electron spin of the intermediate product. Moreover, the sign of the mass-independent fractionation is found to be dependent on the element and its species, which is also explained by the magnetic isotope effect. For example, highly negative mass-independent isotope fractionation of magnetic isotopes was observed for reactions of DC18C6 with SnCl(2) species and with several Ru(III) chloro-species, and highly positive for reactions of this ether with TeCl(6)(2-), and with several Cd(II) and Pd(II) species. The atomic radius of an element is also a critical parameter for the reaction with crown ether, particularly the element ions with [Kr]4d(n)5s(m) electron shell fits the best with the DC18C6 crown ring. It is demonstrated that the magnetic isotope effect in combination with the theory of orbital hybridization can help to understand the mechanism of complexation reactions. The suggested approach is also applied to explain previously published mass-independent fractionation of Hg isotopes in other types of chemical exchange reactions.
Atomic Orbitals for the New Millennium
Williams, J M
1999-01-01
This very short article introduces a set of nested atomic orbitals, called MCAS, to replace the current s, p, d, and f orbitals. The simplest orbital is a tetrahedrally directed, four lobed, mono-orbital instead of the spherical s orbital. All the other orbitals, no matter what their energy (shell) level is, are nested with this one. All the electrons have the same spin and only one electron is allotted to each orbital. Electron spin pairing is accomplished through opposing orbitals instead of actual electron spin reversal. Orbital energy level is maintained by nuclear propulsion through perigee kick. Orbitals hybridize as Aufbau proceeds, in contrast to the inflexible, current building model. The inert gases have completely uniform electronic shells that contain only one orbital type per shell. Since outer completed shells have only one type of orbital, all eight outer electrons are identical rather than being of two types as occurs in the current model; hence, Lewis' electron-dot octet. Hydrogen should resi...
Willitsch, Stefan
2014-01-01
The study of interactions between simultaneously trapped cold ions and atoms has emerged as a new research direction in recent years. The development of ion-atom hybrid experiments has paved the way for investigating elastic, inelastic and reactive collisions between these species at very low temperatures, for exploring new cooling mechanisms of ions by atoms and for implementing new hybrid quantum systems. The present lecture reviews experimental methods, recent results and upcoming developments in this emerging field.
Electronic structure interpolation via atomic orbitals.
Chen, Mohan; Guo, G-C; He, Lixin
2011-08-17
We present an efficient scheme for accurate electronic structure interpolation based on systematically improvable optimized atomic orbitals. The atomic orbitals are generated by minimizing the spillage value between the atomic basis calculations and the converged plane wave basis calculations on some coarse k-point grid. They are then used to calculate the band structure of the full Brillouin zone using the linear combination of atomic orbitals algorithms. We find that usually 16-25 orbitals per atom can give an accuracy of about 10 meV compared to the full ab initio calculations, and the accuracy can be systematically improved by using more atomic orbitals. The scheme is easy to implement and robust, and works equally well for metallic systems and systems with complicated band structures. Furthermore, the atomic orbitals have much better transferability than Shirley's basis and Wannier functions, which is very useful for perturbation calculations.
Atom-Light Hybrid Interferometer.
Chen, Bing; Qiu, Cheng; Chen, Shuying; Guo, Jinxian; Chen, L Q; Ou, Z Y; Zhang, Weiping
2015-07-24
A new type of hybrid atom-light interferometer is demonstrated with atomic Raman amplification processes replacing the beam splitting elements in a traditional interferometer. This nonconventional interferometer involves correlated optical and atomic waves in the two arms. The correlation between atoms and light developed with the Raman process makes this interferometer different from conventional interferometers with linear beam splitters. It is observed that the high-contrast interference fringes are sensitive to the optical phase via a path change as well as the atomic phase via a magnetic field change. This new atom-light correlated hybrid interferometer is a sensitive probe of the atomic internal state and should find wide applications in precision measurement and quantum control with atoms and photons.
Atoms in parallel fields: Analysis with diffractive periodic orbits
Owen, S. M.; Monteiro, T. S.; Dando, P. A.
2000-11-01
We show that fluctuations in the density of states of nonhydrogenic atoms in parallel fields are strongly influenced by diffractive periodic orbits. Unlike typical systems with a diffractive point scatterer, the atomic core of small atoms like lithium and helium is best understood as a combined geometric and diffractive scatterer. Each Gutzwiller (geometric) periodic orbit is paired with a diffractive orbit of the same action. We investigate, particularly, amplitudes for contributions from repetitions, and multiple scattering orbits. We find that periodic orbit repetitions are described by ``hybrid'' orbits, combining both diffractive and geometric core scatters, and that by including all possible permutations we can obtain excellent agreement between the semiclassical model and accurate fully quantal calculations. For high repetitions, we find even one-scatter diffractive contributions become of the same order as those of the geometric periodic orbit for repetition numbers n~ħ-1/2. Although the contribution of individual diffractive orbits is suppressed by O(ħ1/2) relative to the geometric periodic orbits, the proliferation of diffractive orbits with increasing period means that the diffractive effect for the atom can persist in the ħ-->0 limit.
Directory of Open Access Journals (Sweden)
Masato Ohnishi
2015-04-01
Full Text Available When a radial strain is applied to a carbon nanotube (CNT, the increase in local curvature induces orbital hybridization. The effect of the curvature-induced orbital hybridization on the electronic properties of CNTs, however, has not been evaluated quantitatively. In this study, the strength of orbital hybridization in CNTs under homogeneous radial strain was evaluated quantitatively. Our analyses revealed the detailed procedure of the change in electronic structure of CNTs. In addition, the dihedral angle, the angle between π-orbital axis vectors of adjacent atoms, was found to effectively predict the strength of local orbital hybridization in deformed CNTs.
Yu, Deshui; Hufnagel, C; Kwek, L C; Amico, Luigi; Dumke, R
2016-01-01
We investigate a novel hybrid system of a superconducting charge qubit interacting directly with a single neutral atom via electric dipole coupling. Interfacing of the macroscopic superconducting circuit with the microscopic atomic system is accomplished by varying the gate capacitance of the charge qubit. To achieve strong interaction, we employ two Rydberg states with an electric-dipole-allowed transition, which alters the polarizability of the dielectric medium of the gate capacitor. Sweeping the gate voltage with different rates leads to a precise control of hybrid quantum states. Furthermore, we show a possible implementation of a universal two-qubit gate.
Software for Hydrogenic Atoms and Orbitals Visualization
Directory of Open Access Journals (Sweden)
Kowit KITTIWUTTHISAKDI
2005-06-01
Full Text Available A program was developed in java for hydrogenic atoms and orbitals visualization. The first 18 atoms in the periodic table were approximated with a hydrogenic wave-function. This simple hydrogenic wave-function allowed quick calculation for real-time interactive visualization. Electron cloud based models were employed and displayed by a ray-tracing technique. One or more orbitals that defined an atom could be selected and displayed. A user could zoom in, zoom out, and rotate the displayed cloud in real time. The approximation method for probability integrals was summation. The intensity of color at each point on the screen directly related to the integrated probability in finding the electron across the viewer%s eye path.
Atomic orbital self-energy and electronegativity
Ribeiro, Mauro
2016-01-01
In this work, atomic calculations were performed within the local-density and generalized-gradient approximations of exchange and correlation density functionals within density-functional theory to provide accurate periodic trends of first ionization energies and electron affinities of the atomic series from hydrogen to xenon. Electronegativities were determined directly from Mulliken's formula and were shown to be equivalently calculated rather by using Slater-Janak's transition state or by calculating the electrostatic self-energies of the orbitals involved in the transition to ions. Finally, comparisons were made with other theoretical and experimental results, including Mulliken-Jaff\\'e's electronegativity scale.
Superconducting qubit-resonator-atom hybrid system
Yu, Deshui; Kwek, Leong Chuan; Amico, Luigi; Dumke, Rainer
2017-09-01
We propose a hybrid quantum system where an LC resonator inductively interacts with a flux qubit and is capacitively coupled to a Rydberg atom. Varying the external magnetic flux bias controls the flux qubit flipping and the flux qubit-resonator interface. The atomic spectrum is tuned via an electrostatic field, manipulating the qubit-state transition of atom and the atom-resonator coupling. Different types of entanglement of superconducting, photonic and atomic qubits can be prepared via simply tuning the flux bias and electrostatic field, leading to the implementation of three-qubit Toffoli logic gate.
Spin-sensitive atom mirror via spin-orbit interaction
Zhou, Lu; Zheng, Ren-Fei; Zhang, Weiping
2016-11-01
Based on the spin-orbit coupling recently implemented in a neutral cold-atom gas, we propose a scheme to realize spin-dependent scattering of cold atoms. In particular we consider a matter wave packet of cold-atom gas impinging upon a step potential created by the optical light field, inside of which the atoms are subject to spin-orbit interaction. We show that the proposed system can act as a spin polarizer or spin-selective atom mirror for the incident atomic beam. The principle and the operating parameter regime of the system are carefully discussed.
Periodic Orbit Theory for Rydberg Atoms in External Fields
Dando, P. A.; Monteiro, T. S.; Owen, S. M.
1998-03-01
Although hydrogen in external fields is a paradigm for the application of periodic orbits and the Gutzwiller trace formula to a real system, the trace formula has never been applied successfully to other Rydberg atoms. We show that spectral fluctuations of general Rydberg atoms are given with remarkable precision by the addition of diffractive terms. Previously unknown features in atomic spectra are exposed: there are new modulations that are neither periodic orbits nor combinations of periodic orbits; ``core shadowing'' generally decreases primitive periodic orbit amplitudes but can also lead to increases.
Periodic Orbit Theory for Rydberg Atoms in External Fields
Dando, P A; Owen, S M
1998-01-01
Although hydrogen in external fields is a paradigm for the application of periodic orbits and the Gutzwiller trace formula to a real system, the trace formula has never been applied successfully to other Rydberg atoms. We show that spectral fluctuations of general Rydberg atoms are given with remarkable precision by the addition of diffractive terms. Previously unknown features in atomic spectra are exposed: there are new modulations that are neither periodic orbits nor combinations of periodic orbits; `core-shadowing' generally decreases primitive periodic orbit amplitudes but can also lead to increases.
Hybrid ion, atom and light trap
Jyothi, S; Ram, N Bhargava; Rangwala, S A
2013-01-01
We present an unique experimental arrangement which permits the simultaneous trapping and cooling of ions and neutral atoms, within a Fabry-Perot (FP) cavity. The versatility of this hybrid trap experiment enables a variety of studies with trapped mixtures. The motivations behind the production of such a hybrid trap system are explained, followed by details of how the experiment is put together. Several experiments that have been performed with this system are presented and some opportunities with this system are discussed. However the primary emphasis is focussed on the aspects that pertain to the trapped ions, in this hybrid system.
Hybrid quantum systems of atoms and ions
Zipkes, Christoph; Palzer, Stefan; Sias, Carlo; Köhl, Michael
2010-01-01
In recent years, ultracold atoms have emerged as an exceptionally controllable experimental system to investigate fundamental physics, ranging from quantum information science to simulations of condensed matter models. Here we go one step further and explore how cold atoms can be combined with other quantum systems to create new quantum hybrids with tailored properties. Coupling atomic quantum many-body states to an independently controllable single-particle gives access to a wealth of novel physics and to completely new detection and manipulation techniques. We report on recent experiments in which we have for the first time deterministically placed a single ion into an atomic Bose Einstein condensate. A trapped ion, which currently constitutes the most pristine single particle quantum system, can be observed and manipulated at the single particle level. In this single-particle/many-body composite quantum system we show sympathetic cooling of the ion and observe chemical reactions of single particles in situ...
Hybrid quantum systems of atoms and ions
Energy Technology Data Exchange (ETDEWEB)
Zipkes, Christoph; Ratschbacher, Lothar; Palzer, Stefan; Sias, Carlo; Koehl, Michael [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)
2011-01-10
In recent years, ultracold atoms have emerged as an exceptionally controllable experimental system to investigate fundamental physics, ranging from quantum information science to simulations of condensed matter models. Here we go one step further and explore how cold atoms can be combined with other quantum systems to create new quantum hybrids with tailored properties. Coupling atomic quantum many-body states to an independently controllable single-particle gives access to a wealth of novel physics and to completely new detection and manipulation techniques. We report on recent experiments in which we have for the first time deterministically placed a single ion into an atomic Bose Einstein condensate. A trapped ion, which currently constitutes the most pristine single particle quantum system, can be observed and manipulated at the single particle level. In this single-particle/many-body composite quantum system we show sympathetic cooling of the ion and observe chemical reactions of single particles in situ.
Vortex line in spin-orbit coupled atomic Fermi gases
2012-01-01
PHYSICAL REVIEW A 85, 013622 (2012) Vortex line in spin-orbit coupled atomic Fermi gases M. Iskin Department of Physics, Koc¸ University, Rumelifeneri Yolu, TR-34450 Sariyer, Istanbul, Turkey (Received 1 December 2011; published 17 January 2012) It has recently been shown that the spin-orbit coupling gives rise to topologically nontrivial and thermodynamically stable gapless superfluid phases when the pseudospin populations of an atomic Fermi gas are imbalanced, with the ...
Production of Fine Metallic Powders by Hybrid Atomization Process
Minagawa, Kazumi; Liu, Yunzhong; Kakisawa, Hideki; Halada, Kohmei
Hybrid Atomization is a recently developed powder-making process that combines effectively free-fall gas atomization and centrifugal atomization. This technique can produce very fine spherical powders with mean diameters of around 10 micrometers, and in high yields. The present report discusses the concept and basic principles of hybrid atomization. Process experiments were carried out and the optimal processing conditions were obtained. The results show that the influences of processing parameters and optimum conditions differ greatly between the proposed and the conventional atomization processes. A new correlation of atomization equation applicable to hybrid atomization is proposed and discussed.
Orbital Feshbach Resonance in Alkali-Earth Atoms.
Zhang, Ren; Cheng, Yanting; Zhai, Hui; Zhang, Peng
2015-09-25
For a mixture of alkali-earth atomic gas in the long-lived excited state ^{3}P_{0} and the ground state ^{1}S_{0}, in addition to nuclear spin, another "orbital" index is introduced to distinguish these two internal states. In this Letter we propose a mechanism to induce Feshbach resonance between two atoms with different orbital and nuclear spin quantum numbers. Two essential ingredients are the interorbital spin-exchange process and orbital dependence of the Landé g factors. Here the orbital degrees of freedom plays a similar role as the electron spin degree of freedom in magnetic Feshbach resonance in alkali-metal atoms. This resonance is particularly accessible for the ^{173}Yb system. The BCS-BEC crossover in this system requires two fermion pairing order parameters, and displays a significant difference compared to that in an alkali-metal system.
Role of core-scattered closed orbits in nonhydrogenic atoms
Dando, P. A.; Monteiro, T. S.; Delande, D.; Taylor, K. T.
1996-07-01
While both diamagnetic and Stark spectra of hydrogen can be analyzed accurately in terms of classical orbits, in nonhydrogenic atoms the multielectron core induces additional spectral modulations that cannot be analyzed reliably in terms of standard periodic orbit-type theories. However, by extending closed-orbit theory to include core-scattered waves consistently, both diamagnetic and Stark photoabsorption spectra of nonhydrogenic Rydberg atoms at constant scaled energy can be analyzed semiclassically using only the closed orbits of the corresponding hydrogenic systems. Frequencies and amplitudes of the core-scattered modulations, as well as corrected amplitudes for contributions from repetitions of primitive hydrogenic orbits, are found to be in excellent agreement with quantum results. We consider whether these nonhydrogenic systems correspond to quantum chaos.
Hydrodynamics of Normal Atomic Gases with Spin-orbit Coupling.
Hou, Yan-Hua; Yu, Zhenhua
2015-10-20
Successful realization of spin-orbit coupling in atomic gases by the NIST scheme opens the prospect of studying the effects of spin-orbit coupling on many-body physics in an unprecedentedly controllable way. Here we derive the linearized hydrodynamic equations for the normal atomic gases of the spin-orbit coupling by the NIST scheme with zero detuning. We show that the hydrodynamics of the system crucially depends on the momentum susceptibilities which can be modified by the spin-orbit coupling. We reveal the effects of the spin-orbit coupling on the sound velocities and the dipole mode frequency of the gases by applying our formalism to the ideal Fermi gas. We also discuss the generalization of our results to other situations.
Manipulating atomic states via optical orbital angular-momentum
Institute of Scientific and Technical Information of China (English)
2008-01-01
Optical orbital angular-momentum(OAM)has more complex mechanics than the spin degree of photons,and may have a broad range of application.Manipulating atomic states via OAM has become an interesting topic.In this paper,we first review the general theory of generating adiabatic gauge field in ultracold atomic systems by coupling atoms to external optical fields with OAM,and point out the applications of the generated adiabatic gauge field.Then,we review our work in this field,including the generation of macroscopic superposition of vortex-antivortex states and spin Hall effect(SHE)in cold atoms.
Spin-orbit hybrid entanglement of photons and quantum contextuality
Karimi, Ebrahim; Slussarenko, Sergei; Piccirillo, Bruno; Marrucci, Lorenzo; Chen, Lixiang; She, Weilong; Franke-Arnold, Sonja; Padgett, Miles J; Santamato, Enrico; 10.1103/PhysRevA.82.022115
2011-01-01
We demonstrate electromagnetic quantum states of single photons and of correlated photon pairs exhibiting "hybrid" entanglement between spin and orbital angular momentum. These states are obtained from entangled photon pairs emitted by spontaneous parametric down conversion, by employing a $q$-plate for coupling the spin and orbital degrees of freedom of a photon. Entanglement and contextual quantum behavior (that is also non-local, in the case of photon pairs) is demonstrated by the reported violation of the Clauser-Horne-Shimony-Holt inequality. In addition a classical analog of the hybrid spin-orbit photonic entanglement is reported and discussed.
Hybrid Atom Electrostatic System for Satellite Geodesy
Zahzam, Nassim; Bidel, Yannick; Bresson, Alexandre; Huynh, Phuong-Anh; Liorzou, Françoise; Lebat, Vincent; Foulon, Bernard; Christophe, Bruno
2017-04-01
The subject of this poster comes within the framework of new concepts identification and development for future satellite gravity missions, in continuation of previously launched space missions CHAMP, GRACE, GOCE and ongoing and prospective studies like NGGM, GRACE 2 or E-GRASP. We were here more focused on the inertial sensors that complete the payload of such satellites. The clearly identified instruments for space accelerometry are based on the electrostatic technology developed for many years by ONERA and that offer a high level of performance and a high degree of maturity for space applications. On the other hand, a new generation of sensors based on cold atom interferometry (AI) is emerging and seems very promising in this context. These atomic instruments have already demonstrated on ground impressive results, especially with the development of state-of-the-art gravimeters, and should reach their full potential only in space, where the microgravity environment allows long interaction times. Each of these two types of instruments presents their own advantages which are, for the electrostatic sensors (ES), their demonstrated short term sensitivity and their high TRL, and for AI, amongst others, the absolute nature of the measurement and therefore no need for calibration processes. These two technologies seem in some aspects very complementary and a hybrid sensor bringing together all their assets could be the opportunity to take a big step in this context of gravity space missions. We present here the first experimental association on ground of an electrostatic accelerometer and an atomic accelerometer and underline the interest of calibrating the ES instrument with the AI. Some technical methods using the ES proof-mass as the Raman Mirror seem very promising to remove rotation effects of the satellite on the AI signal. We propose a roadmap to explore further in details and more rigorously this attractive hybridization scheme in order to assess its potential
Beyond periodic orbits: An example in nonhydrogenic atoms
Energy Technology Data Exchange (ETDEWEB)
Dando, P.A.; Monteiro, T.S.; Delande, D.; Taylor, K.T. (Department of Mathematics, Royal Holloway, University of London, Egham, Surrey, TW20 0EX (United Kingdom) Laboratoire Kastler-Brossel, Universite Pierre et Marie Curie, 4 place Jussieu, F-75005 Paris (France) Department of Applied Mathematics and Theoretical Physics, Queen' s University Belfast, Belfast, BT7 1NN (United Kingdom))
1995-02-13
The spectrum of hydrogen in a magnetic field is a paradigm of quantum chaos and may be analyzed accurately by periodic-orbit-type theories. In nonhydrogenic atoms, the core induces pure quantum effects, especially additional spectral modulations, which cannot be analyzed reliably in terms of classical orbits and their stability parameters. Provided core-scattered waves are included consistently, core-scattered modulations as well as corrected amplitudes for primitive orbits are in excellent agreement with quantum results. We consider whether these systems correspond to quantum chaos.
Beyond Periodic Orbits: An Example in Nonhydrogenic Atoms
Dando, P. A.; Monteiro, T. S.; Delande, D.; Taylor, K. T.
1995-02-01
The spectrum of hydrogen in a magnetic field is a paradigm of quantum chaos and may be analyzed accurately by periodic-orbit-type theories. In nonhydrogenic atoms, the core induces pure quantum effects, especially additional spectral modulations, which cannot be analyzed reliably in terms of classical orbits and their stability parameters. Provided core-scattered waves are included consistently, core-scattered modulations as well as corrected amplitudes for primitive orbits are in excellent agreement with quantum results. We consider whether these systems correspond to quantum chaos.
Translation and integration of numerical atomic orbitals in linear molecules
Energy Technology Data Exchange (ETDEWEB)
Heinäsmäki, Sami, E-mail: sami.heinasmaki@gmail.com [Department of Physics, University of Oulu, FIN-90014, Oulu (Finland)
2014-02-14
We present algorithms for translation and integration of atomic orbitals for LCAO calculations in linear molecules. The method applies to arbitrary radial functions given on a numerical mesh. The algorithms are based on pseudospectral differentiation matrices in two dimensions and the corresponding two-dimensional Gaussian quadratures. As a result, multicenter overlap and Coulomb integrals can be evaluated effectively.
Super-atom molecular orbital excited states of fullerenes.
Johansson, J Olof; Bohl, Elvira; Campbell, Eleanor E B
2016-09-13
Super-atom molecular orbitals are orbitals that form diffuse hydrogenic excited electronic states of fullerenes with their electron density centred at the centre of the hollow carbon cage and a significant electron density inside the cage. This is a consequence of the high symmetry and hollow structure of the molecules and distinguishes them from typical low-lying molecular Rydberg states. This review summarizes the current experimental and theoretical studies related to these exotic excited electronic states with emphasis on femtosecond photoelectron spectroscopy experiments on gas-phase fullerenes.This article is part of the themed issue 'Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene'.
Natural atomic orbital based energy density analysis: Implementation and applications
Baba, Takeshi; Takeuchi, Mari; Nakai, Hiromi
2006-06-01
We present an improvement of energy density analysis (EDA), which partitions the total energy obtained by Hartree-Fock and/or density functional theory calculations, with the use of the natural atomic orbital (NAO) [A.E. Reed et al., J. Chem. Phys. 83 (1985) 735] and Löwdin's symmetric-orthogonal orbital (LSO). The present NAO- and LSO-EDA schemes are applied to analyses of CO 2 and Li9+ with various basis sets. Numerical results confirm that NAO-EDA exhibits less basis-set dependence, while the conventional results are very sensitive to the adopted basis sets.
Multiple orbital angular momentum generated by dielectric hybrid phase element
Wang, Xuewen; Kuchmizhak, Aleksandr; Hu, Dejiao; Li, Xiangping
2017-09-01
Vortex beam carrying multiple orbital angular momentum provides a new degree of freedom to manipulate light leading to the various exciting applications as trapping, quantum optics, information multiplexing, etc. Helical wavefront can be generated either via the geometric or the dynamic phase arising from a space-variant birefringence (q-plate) or from phase accumulation through propagation (spiral-phase-plate), respectively. Using fast direct laser writing technique we fabricate and characterize novel hybrid q-plate generating vortex beam simultaneously carrying two different high-order topological charges, which arise from the spin-orbital conversion and the azimuthal height variation of the recorded structures. We approve the versatile concept to generate multiple-OAM vortex beams combining the spin-orbital interaction and the phase accumulation in a single micro-scale device, a hybrid dielectric phase plate.
Dimension Reduction Near Periodic Orbits of Hybrid Systems
Burden, Samuel; Sastry, S Shankar
2011-01-01
When the Poincar\\'{e} map associated with a periodic orbit of a hybrid dynamical system has constant-rank iterates, we demonstrate the existence of a constant-dimensional invariant subsystem near the orbit which attracts all nearby trajectories in finite time. This result shows that the long-term behavior of a hybrid model with a large number of degrees-of-freedom may be governed by a low-dimensional smooth dynamical system. The appearance of such simplified models enables the translation of analytical tools from smooth systems-such as Floquet theory-to the hybrid setting and provides a bridge between the efforts of biologists and engineers studying legged locomotion.
Transferring orbital and spin angular momenta of light to atoms
Energy Technology Data Exchange (ETDEWEB)
Picon, A; Benseny, A; Mompart, J [Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Vazquez de Aldana, J R; Plaja, L [Servicio Laser, Universidad de Salamanca, E-37008 Salamanca (Spain); Calvo, G F [Mathematics Department and IMACI-Institute of Applied Mathematics in Science and Engineering, Universidad de Castilla-La Mancha, E-13071 Ciudad Real (Spain); Roso, L, E-mail: antonio.picon@uab.ca [Centro de Laseres Pulsados, CLPU, Patio de Escuelas 1, E-37008 Salamanca (Spain)
2010-08-15
Light beams carrying orbital angular momentum (OAM), such as Laguerre-Gaussian (LG) beams, give rise to the violation of the standard dipolar selection rules during interaction with matter, yielding, in general, an exchange of angular momentum larger than {h_bar} per absorbed photon. By means of ab initio three-dimensional (3D) numerical simulations, we investigate in detail the interaction of a hydrogen atom with intense Gaussian and LG light pulses. We analyze the dependence of the angular momentum exchange with the polarization, the OAM and the carrier-envelope phase of light, as well as with the relative position between the atom and the light vortex. In addition, a quantum-trajectory approach based on the de Broglie-Bohm formulation of quantum mechanics is used to gain physical insight into the absorption of angular momentum by the hydrogen atom.
Atomic oxygen effects on POSS polyimides in low earth orbit.
Minton, Timothy K; Wright, Michael E; Tomczak, Sandra J; Marquez, Sara A; Shen, Linhan; Brunsvold, Amy L; Cooper, Russell; Zhang, Jianming; Vij, Vandana; Guenthner, Andrew J; Petteys, Brian J
2012-02-01
Kapton polyimde is extensively used in solar arrays, spacecraft thermal blankets, and space inflatable structures. Upon exposure to atomic oxygen in low Earth orbit (LEO), Kapton is severely eroded. An effective approach to prevent this erosion is to incorporate polyhedral oligomeric silsesquioxane (POSS) into the polyimide matrix by copolymerizing POSS monomers with the polyimide precursor. The copolymerization of POSS provides Si and O in the polymer matrix on the nano level. During exposure of POSS polyimide to atomic oxygen, organic material is degraded, and a silica passivation layer is formed. This silica layer protects the underlying polymer from further degradation. Laboratory and space-flight experiments have shown that POSS polyimides are highly resistant to atomic-oxygen attack, with erosion yields that may be as little as 1% those of Kapton. The results of all the studies indicate that POSS polyimide would be a space-survivable replacement for Kapton on spacecraft that operate in the LEO environment.
Embedded-cluster calculations in a numeric atomic orbital density-functional theory framework.
Berger, Daniel; Logsdail, Andrew J; Oberhofer, Harald; Farrow, Matthew R; Catlow, C Richard A; Sherwood, Paul; Sokol, Alexey A; Blum, Volker; Reuter, Karsten
2014-07-14
We integrate the all-electron electronic structure code FHI-aims into the general ChemShell package for solid-state embedding quantum and molecular mechanical (QM/MM) calculations. A major undertaking in this integration is the implementation of pseudopotential functionality into FHI-aims to describe cations at the QM/MM boundary through effective core potentials and therewith prevent spurious overpolarization of the electronic density. Based on numeric atomic orbital basis sets, FHI-aims offers particularly efficient access to exact exchange and second order perturbation theory, rendering the established QM/MM setup an ideal tool for hybrid and double-hybrid level density functional theory calculations of solid systems. We illustrate this capability by calculating the reduction potential of Fe in the Fe-substituted ZSM-5 zeolitic framework and the reaction energy profile for (photo-)catalytic water oxidation at TiO2(110).
Embedded-cluster calculations in a numeric atomic orbital density-functional theory framework
Berger, Daniel; Logsdail, Andrew J.; Oberhofer, Harald; Farrow, Matthew R.; Catlow, C. Richard A.; Sherwood, Paul; Sokol, Alexey A.; Blum, Volker; Reuter, Karsten
2014-07-01
We integrate the all-electron electronic structure code FHI-aims into the general ChemShell package for solid-state embedding quantum and molecular mechanical (QM/MM) calculations. A major undertaking in this integration is the implementation of pseudopotential functionality into FHI-aims to describe cations at the QM/MM boundary through effective core potentials and therewith prevent spurious overpolarization of the electronic density. Based on numeric atomic orbital basis sets, FHI-aims offers particularly efficient access to exact exchange and second order perturbation theory, rendering the established QM/MM setup an ideal tool for hybrid and double-hybrid level density functional theory calculations of solid systems. We illustrate this capability by calculating the reduction potential of Fe in the Fe-substituted ZSM-5 zeolitic framework and the reaction energy profile for (photo-)catalytic water oxidation at TiO2(110).
Exchange-correlation interaction and AO-hybridization of alkali-metal atomic clusters.
Liu, Xuan; Ito, Haruhiko; Torikai, Eiko
2013-09-19
The structure of alkali-metal atomic clusters is optimized with B3P86 hybrid functional for the highest spin state as well as with B3LYP hybrid functional for the lowest spin state. A dramatic change from plane to solid occurs in the highest spin state when the number of constituent atoms is four. The binding, exchange, and correlation energies are evaluated for both the highest and lowest spin states. Next, we explore the dependence of the exchange and correlation energies on the binding energy. The exchange energy contributes to the formation of the highest spin clusters, whereas the correlation energy contributes to the formation of the lowest spin clusters. The highest spin clusters are most stable when the exchange energy is a minimum. Then, to see why the ferromagnetic bond among spin-aligned identical atoms arises against Pauli exclusion principle, we estimate the mixing ratio of p orbitals in molecular orbitals. The s-p hybridization increases the binding energy in absolute value due to the extensive overlap of molecular orbitals and leads to generation of the highest spin clusters.
Spin-orbit interactions and quantum spin dynamics in cold ion-atom collisions
Tscherbul, Timur V; Buchachenko, Alexei A
2015-01-01
We present accurate ab initio and quantum scattering calculations on a prototypical hybrid ion-atom system Yb$^+$-Rb, recently suggested as a promising candidate for the experimental study of open quantum systems, quantum information processing, and quantum simulation. We identify the second-oder spin-orbit (SO) interaction as the dominant source of hyperfine relaxation and decoherence in cold Yb$^+$-Rb collisions. Our results are in good agreement with recent experimental observations [L. Ratschbacher et al., Phys. Rev. Lett. 110, 160402 (2013)] of hyperfine relaxation rates of trapped Yb$^+$ immersed in an ultracold Rb gas. The calculated rates are 4 times smaller than predicted by the Langevin capture theory and display a weak $T^{-0.3}$ temperature dependence, indicating significant deviations from statistical behavior. Our analysis underscores the deleterious nature of the SO interaction and implies that light ion-atom combinations such as Yb$^+$-Li should be used to minimize hyperfine relaxation and dec...
Liguori, Lucia
2014-01-01
Atomic orbital theory is a difficult subject for many high school and beginning undergraduate students, as it includes mathematical concepts not yet covered in the school curriculum. Moreover, it requires certain ability for abstraction and imagination. A new atomic orbital model "the chocolate shop" created "by" students…
Liguori, Lucia
2014-01-01
Atomic orbital theory is a difficult subject for many high school and beginning undergraduate students, as it includes mathematical concepts not yet covered in the school curriculum. Moreover, it requires certain ability for abstraction and imagination. A new atomic orbital model "the chocolate shop" created "by" students…
A dense gas of laser-cooled atoms for hybrid atom-ion trapping
Höltkemeier, Bastian; Glässel, Julian; López-Carrera, Henry; Weidemüller, Matthias
2017-01-01
We describe the realization of a dark spontaneous-force trap of rubidium atoms. The atoms are loaded from a beam provided by a two-dimensional magneto-optical trap yielding a capture efficiency of 75%. The dense and cold atomic sample is characterized by saturated absorption imaging. Up to 10^9 atoms are captured with a loading rate of 3× 10^9 atoms/s into a cloud at a temperature of 250 μK with the density exceeding 10^{11} atoms/cm^3. Under steady-state conditions, more than 90% of the atoms can be prepared into the absolute atomic ground state, which provides favorable conditions for the investigation of sympathetic cooling of ions in a hybrid atom-ion trap.
Hybridization Induced Transparency in composites of metamaterials and atomic media
Weis, Peter; Beigang, René; Rahm, Marco
2011-01-01
We report hybridization induced transparency (HIT) in a composite medium consisting of a metamaterial and a dielectric. We develop an analytic model that explains HIT by coherent coupling between the hybridized local fields of the metamaterial and the dielectric or an atomic system in general. In a proof-of-principle experiment, we evidence HIT in a split ring resonator metamaterial that is coupled to \\alpha-lactose monohydrate. Both, the analytic model and numerical calculations confirm and explain the experimental observations. HIT can be considered as a hybrid analogue to electromagnetically induced transparency (EIT) and plasmon-induced transparency (PIT).
Science Hybrid Orbiter and Lunar Relay (SCHOLR) Architecture and Design
Trase, Kathryn K.; Barch, Rachel A.; Chaney, Ryan E.; Coulter, Rachel A.; Gao, Hui; Huynh, David P.; Iaconis, Nicholas A.; MacMillan, Todd S.; Pitner, Gregory M.; Schwab, Devin T.
2011-01-01
Considered both a stepping-stone to deep space and a key to unlocking the mysteries of planetary formation, the Moon offers a unique opportunity for scientific study. Robotic precursor missions are being developed to improve technology and enable new approaches to exploration. Robots, lunar landers, and satellites play significant roles in advancing science and technologies, offering close range and in-situ observations. Science and exploration data gathered from these nodes and a lunar science satellite is intended to support future human expeditions and facilitate future utilization of lunar resources. To attain a global view of lunar science, the nodes will be distributed over the lunar surface, including locations on the far side of the Moon. Given that nodes on the lunar far side do not have direct line-of-sight for Earth communications, the planned presence of such nodes creates the need for a lunar communications relay satellite. Since the communications relay capability would only be required for a small portion of the satellite s orbit, it may be possible to include communication relay components on a science spacecraft. Furthermore, an integrated satellite has the potential to reduce lunar surface mission costs. A SCience Hybrid Orbiter and Lunar Relay (SCHOLR) is proposed to accomplish scientific goals while also supporting the communications needs of landers on the far side of the Moon. User needs and design drivers for the system were derived from the anticipated needs of future robotic and lander missions. Based on these drivers and user requirements, accommodations for communications payload aboard a science spacecraft were developed. A team of interns identified and compared possible SCHOLR architectures. The final SCHOLR architecture was analyzed in terms of orbiter lifetime, lunar surface coverage, size, mass, power, and communications data rates. This paper presents the driving requirements, operational concept, and architecture views for SCHOLR
Ionocovalency and Applications 1. Ionocovalency Model and Orbital Hybrid Scales
Directory of Open Access Journals (Sweden)
Yonghe Zhang
2010-11-01
Full Text Available Ionocovalency (IC, a quantitative dual nature of the atom, is defined and correlated with quantum-mechanical potential to describe quantitatively the dual properties of the bond. Orbiotal hybrid IC model scale, IC, and IC electronegativity scale, XIC, are proposed, wherein the ionicity and the covalent radius are determined by spectroscopy. Being composed of the ionic function I and the covalent function C, the model describes quantitatively the dual properties of bond strengths, charge density and ionic potential. Based on the atomic electron configuration and the various quantum-mechanical built-up dual parameters, the model formed a Dual Method of the multiple-functional prediction, which has much more versatile and exceptional applications than traditional electronegativity scales and molecular properties. Hydrogen has unconventional values of IC and XIC, lower than that of boron. The IC model can agree fairly well with the data of bond properties and satisfactorily explain chemical observations of elements throughout the Periodic Table.
Imaging of RNA in situ hybridization by atomic force microscopy
Kalle, W.H.J.; Macville, M.V.E.; van de Corput, M.P.C.; de Grooth, B.G.; Tanke, H.J.; Raap, A.K.
In this study we investigated the possibility of imaging internal cellular molecules after cytochemical detection with atomic force microscopy (AFM). To this end, rat 9G and HeLa cells were hybridized with haptenized probes for 28S ribosomal RNA, human elongation factor mRNA and cytomegalovirus
Bridgeman, Adam J.; Schmidt, Timothy W.; Young, Nigel A.
2013-01-01
The stretching modes of ML[subscript "x"] complexes have the same symmetry as the atomic orbitals on M that are used to form its s bonds. In the exercise suggested here, the atomic orbitals are used to derive the form of the stretching modes without the need for formal group theory. The analogy allows students to help understand many…
Bridgeman, Adam J.; Schmidt, Timothy W.; Young, Nigel A.
2013-01-01
The stretching modes of ML[subscript "x"] complexes have the same symmetry as the atomic orbitals on M that are used to form its s bonds. In the exercise suggested here, the atomic orbitals are used to derive the form of the stretching modes without the need for formal group theory. The analogy allows students to help understand many…
DEFF Research Database (Denmark)
Ruud, Kenneth; Helgaker, Trygve; Kobayashi, Rika
1994-01-01
Nuclear shielding calculations are presented for multiconfigurational self-consistent field wave functions using London atomic orbitals (gauge invariant atomic orbitals). Calculations of nuclear shieldings for eight molecules (H2O, H2S, CH4, N2, CO, HF, F2, and SO2) are presented and compared...
Directory of Open Access Journals (Sweden)
Sri Mursiti
2010-06-01
Full Text Available The research of Computer Asissted Instruction with animation and simulation was used to misconception remediation of atomic orbital, molecular orbital, and hibridiziation concepts. The applicated instruction model was focused on concept approach with macromedia flash player and power point programme. The subject of this research were the 2nd semestre students of Chemistry Department. The data were collected by using of true-false pre-test and post- test followed by the reason of its. The analysis reveals that the Computer Asissted Instruction with animation and simulation model increased the understanding of atomic orbital, molecular orbital, and hibridiziation concepts or remediation of concepts missconception, shown by the significant score gained between before and after the implementation of Computer Asissted Instruction with animation and simulation model. The instruction model developed the students's generic skills too. Keywords: animation simulation,misconception remediation, orbital, hibridization
Periodic orbits of hybrid systems and parameter estimation via AD.
Energy Technology Data Exchange (ETDEWEB)
Guckenheimer, John. (Cornell University); Phipps, Eric Todd; Casey, Richard (INRIA Sophia-Antipolis)
2004-07-01
Rhythmic, periodic processes are ubiquitous in biological systems; for example, the heart beat, walking, circadian rhythms and the menstrual cycle. Modeling these processes with high fidelity as periodic orbits of dynamical systems is challenging because: (1) (most) nonlinear differential equations can only be solved numerically; (2) accurate computation requires solving boundary value problems; (3) many problems and solutions are only piecewise smooth; (4) many problems require solving differential-algebraic equations; (5) sensitivity information for parameter dependence of solutions requires solving variational equations; and (6) truncation errors in numerical integration degrade performance of optimization methods for parameter estimation. In addition, mathematical models of biological processes frequently contain many poorly-known parameters, and the problems associated with this impedes the construction of detailed, high-fidelity models. Modelers are often faced with the difficult problem of using simulations of a nonlinear model, with complex dynamics and many parameters, to match experimental data. Improved computational tools for exploring parameter space and fitting models to data are clearly needed. This paper describes techniques for computing periodic orbits in systems of hybrid differential-algebraic equations and parameter estimation methods for fitting these orbits to data. These techniques make extensive use of automatic differentiation to accurately and efficiently evaluate derivatives for time integration, parameter sensitivities, root finding and optimization. The boundary value problem representing a periodic orbit in a hybrid system of differential algebraic equations is discretized via multiple-shooting using a high-degree Taylor series integration method [GM00, Phi03]. Numerical solutions to the shooting equations are then estimated by a Newton process yielding an approximate periodic orbit. A metric is defined for computing the distance
Distributed orbital state quantum cloning with atomic ensembles via quantum Zeno dynamics
Shen, Li-Tuo; Yang, Zhen-Biao
2011-01-01
We propose a scheme for distributed orbital state quantum cloning with atomic ensembles based on the quantum Zeno dynamics. These atomic ensembles which consist of identical three-level atoms are trapped in distant cavities connected by a single-mode integrated optical star coupler. These qubits can be manipulated through appropriate modulation of the coupling constants between atomic ensemble and classical field, and the cavity decay can be largely suppressed as the number of atoms in the ensemble qubits increases. The present scheme provides a new way to construct the quantum communication network.
Grimme, Stefan; Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas
2015-08-01
A density functional theory (DFT) based composite electronic structure approach is proposed to efficiently compute structures and interaction energies in large chemical systems. It is based on the well-known and numerically robust Perdew-Burke-Ernzerhoff (PBE) generalized-gradient-approximation in a modified global hybrid functional with a relatively large amount of non-local Fock-exchange. The orbitals are expanded in Ahlrichs-type valence-double zeta atomic orbital (AO) Gaussian basis sets, which are available for many elements. In order to correct for the basis set superposition error (BSSE) and to account for the important long-range London dispersion effects, our well-established atom-pairwise potentials are used. In the design of the new method, particular attention has been paid to an accurate description of structural parameters in various covalent and non-covalent bonding situations as well as in periodic systems. Together with the recently proposed three-fold corrected (3c) Hartree-Fock method, the new composite scheme (termed PBEh-3c) represents the next member in a hierarchy of "low-cost" electronic structure approaches. They are mainly free of BSSE and account for most interactions in a physically sound and asymptotically correct manner. PBEh-3c yields good results for thermochemical properties in the huge GMTKN30 energy database. Furthermore, the method shows excellent performance for non-covalent interaction energies in small and large complexes. For evaluating its performance on equilibrium structures, a new compilation of standard test sets is suggested. These consist of small (light) molecules, partially flexible, medium-sized organic molecules, molecules comprising heavy main group elements, larger systems with long bonds, 3d-transition metal systems, non-covalently bound complexes (S22 and S66×8 sets), and peptide conformations. For these sets, overall deviations from accurate reference data are smaller than for various other tested DFT methods
Grimme, Stefan; Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas
2015-08-07
A density functional theory (DFT) based composite electronic structure approach is proposed to efficiently compute structures and interaction energies in large chemical systems. It is based on the well-known and numerically robust Perdew-Burke-Ernzerhoff (PBE) generalized-gradient-approximation in a modified global hybrid functional with a relatively large amount of non-local Fock-exchange. The orbitals are expanded in Ahlrichs-type valence-double zeta atomic orbital (AO) Gaussian basis sets, which are available for many elements. In order to correct for the basis set superposition error (BSSE) and to account for the important long-range London dispersion effects, our well-established atom-pairwise potentials are used. In the design of the new method, particular attention has been paid to an accurate description of structural parameters in various covalent and non-covalent bonding situations as well as in periodic systems. Together with the recently proposed three-fold corrected (3c) Hartree-Fock method, the new composite scheme (termed PBEh-3c) represents the next member in a hierarchy of "low-cost" electronic structure approaches. They are mainly free of BSSE and account for most interactions in a physically sound and asymptotically correct manner. PBEh-3c yields good results for thermochemical properties in the huge GMTKN30 energy database. Furthermore, the method shows excellent performance for non-covalent interaction energies in small and large complexes. For evaluating its performance on equilibrium structures, a new compilation of standard test sets is suggested. These consist of small (light) molecules, partially flexible, medium-sized organic molecules, molecules comprising heavy main group elements, larger systems with long bonds, 3d-transition metal systems, non-covalently bound complexes (S22 and S66×8 sets), and peptide conformations. For these sets, overall deviations from accurate reference data are smaller than for various other tested DFT methods
Energy Technology Data Exchange (ETDEWEB)
Grimme, Stefan, E-mail: grimme@thch.uni-bonn.de; Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas [Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms Universität Bonn, Beringstraße 4, 53115 Bonn (Germany)
2015-08-07
A density functional theory (DFT) based composite electronic structure approach is proposed to efficiently compute structures and interaction energies in large chemical systems. It is based on the well-known and numerically robust Perdew-Burke-Ernzerhoff (PBE) generalized-gradient-approximation in a modified global hybrid functional with a relatively large amount of non-local Fock-exchange. The orbitals are expanded in Ahlrichs-type valence-double zeta atomic orbital (AO) Gaussian basis sets, which are available for many elements. In order to correct for the basis set superposition error (BSSE) and to account for the important long-range London dispersion effects, our well-established atom-pairwise potentials are used. In the design of the new method, particular attention has been paid to an accurate description of structural parameters in various covalent and non-covalent bonding situations as well as in periodic systems. Together with the recently proposed three-fold corrected (3c) Hartree-Fock method, the new composite scheme (termed PBEh-3c) represents the next member in a hierarchy of “low-cost” electronic structure approaches. They are mainly free of BSSE and account for most interactions in a physically sound and asymptotically correct manner. PBEh-3c yields good results for thermochemical properties in the huge GMTKN30 energy database. Furthermore, the method shows excellent performance for non-covalent interaction energies in small and large complexes. For evaluating its performance on equilibrium structures, a new compilation of standard test sets is suggested. These consist of small (light) molecules, partially flexible, medium-sized organic molecules, molecules comprising heavy main group elements, larger systems with long bonds, 3d-transition metal systems, non-covalently bound complexes (S22 and S66×8 sets), and peptide conformations. For these sets, overall deviations from accurate reference data are smaller than for various other tested DFT
Spin-splitting calculation for zincblende semiconductors using an atomic bond-orbital model.
Kao, Hsiu-Fen; Lo, Ikai; Chiang, Jih-Chen; Chen, Chun-Nan; Wang, Wan-Tsang; Hsu, Yu-Chi; Ren, Chung-Yuan; Lee, Meng-En; Wu, Chieh-Lung; Gau, Ming-Hong
2012-10-17
We develop a 16-band atomic bond-orbital model (16ABOM) to compute the spin splitting induced by bulk inversion asymmetry in zincblende materials. This model is derived from the linear combination of atomic-orbital (LCAO) scheme such that the characteristics of the real atomic orbitals can be preserved to calculate the spin splitting. The Hamiltonian of 16ABOM is based on a similarity transformation performed on the nearest-neighbor LCAO Hamiltonian with a second-order Taylor expansion k at the Γ point. The spin-splitting energies in bulk zincblende semiconductors, GaAs and InSb, are calculated, and the results agree with the LCAO and first-principles calculations. However, we find that the spin-orbit coupling between bonding and antibonding p-like states, evaluated by the 16ABOM, dominates the spin splitting of the lowest conduction bands in the zincblende materials.
The closed-orbit and the photoabsorption spectra of lithium atom in varyingmagnetic fields
Institute of Scientific and Technical Information of China (English)
Wang De-Hua; Ding Shi-Liang
2004-01-01
@@ Using a simple analytic formula from closed orbit theory, we have calculated the photoabsorption spectra of Li atom in different magnetic fields. Closed orbits in the corresponding classical system have also been obtained for B=5.96T. We demonstrate schematically that the closed orbits disappear gradually with the decrease of the magnitude of the magnetic field. This gives us a good method to control the closed orbits in the corresponding system by changing the magnetic field, and thus changing the peaks in the photoabaorption spectra. By comparing the photoabsorption spectra of Li atom with those of hydrogen case, we find the core-scattered effects play an important role in multi-electron Rydberg atoms.
Mapping trapped atomic gas with spin-orbit coupling to quantum Rabi-like model
Hu, Haiping; Chen, Shu
2013-01-01
We construct a connection of the ultracold atomic system in a harmonic trap with Raman-induced spin-orbit coupling to the quantum Rabi-like model. By mapping the trapped atomic system to a Rabi-like model, we can get the exact solution of the Rabi-like model following the methods to solve the quantum Rabi model. The existence of such a mapping implies that we can study the basic model in quantum optics by using trapped atomic gases with spin-orbit coupling.
QSPR modeling mineral crystal lattice energy by optimal descriptors of the graph of atomic orbitals
Toropova, A. P.; Toropov, A. A.; Maksudov, S. Kh.
2006-09-01
Models of the crystal lattice of minerals of general formula of A mC n: m, n = 1,2: A = Li, K, Na, Mg, Ca, Mn, Cu, Zn, Sr, Cd, Ba, Hg, Pb, Cs, and Rb ; C = Be, O, F, S, Cl, Br, and I; as a mathematical function of their structure have been constructed. Two elucidations of molecular structure have been used: molecular graph (vertexes are atoms, i.e., Li, Na, K, etc.) and graph of atomic orbitals, GAO (vertexes are atomic orbitals, i.e., 1s 2, 2p 5, 3d 10, etc). Statistical characteristics of the GAO-based models are better.
Orbital Battleship: A Guessing Game to Reinforce Atomic Structure
Kurushkin, Mikhail; Mikhaylenko, Maria
2016-01-01
A competitive educational guessing game "Orbital Battleship" which reinforces Madelung's and Hund's rules, values of quantum numbers, and understanding of periodicity was designed. The game develops strategic thinking, is not time-consuming, requires minimal preparation and supervision, and is an efficient and fun alternative to more…
On the Role of D Orbital Hybridization in the Chemistry Curriculum
Galbraith, John Morrison
2007-01-01
The role of d-orbital hybridization in the chemistry curriculum and a qualitative description of bonding in SF[subscript 6] are described. The sp[cubed]d[squared] hybridization model found to be helpful in understanding the chemical phenomenon of chemical bonding in SF[subscript 6] and are not applicable to all situations.
Mikajlo, E A; Ford, M J
2003-01-01
This paper presents an experimental measurement of the electronic structure of Na sub 2 O in the solid phase using electron momentum spectroscopy and compares the results with ab initio calculations performed within the linear combination of atomic orbitals (LCAO) approximation. While Hartree-Fock (HF) can reproduce elastic properties we find it overestimates splitting of the oxygen valence bands by around 30% and the width of the O 2p band by a factor of 2. Our experimental values are 15.85 +- 0.2 and 0.6 +- 0.2 eV for these two quantities, respectively. Density functional methods are significantly better, with the hybrid functional PBE0 predicting the oxygen bandgap to within the experimental error. PBE0 also gives the best estimate of the Na core level energies. In contrast, HF performs best for the splitting between the oxygen and sodium bands. Our experimental values of 32.85 +- 0.2 and 27.45 +- 0.2 eV for the Na 2p-Na 2s and O 2p-Na 2p splittings agree well with previous measurements. Distribution of el...
Institute of Scientific and Technical Information of China (English)
YAKAR,Yusuf
2007-01-01
Ab initio calculations of the orbital and the ground state energies of some open- and closed-shell atoms over Slater type orbitals with quantum numbers integer and Slater type orbitals with quantum numbers noninteger have been performed. In order to increase the efficiency of these calculations the atomic two-electron integrals were expressed in terms of incomplete beta function. Results were observed to be in good agreement with the literature.
Strong spin-orbit interaction of light on the surface of atomically thin crystals
Liu, Mengxia; Cai, Liang; Chen, Shizhen; Liu, Yachao; Luo, Hailu; Wen, Shuangchun
2017-06-01
The photonic spin Hall effect (SHE) can be regarded as a direct optical analogy of the SHE in electronic systems where a refractive index gradient plays the role of an electric potential. However, it has been demonstrated that the effective refractive index fails to adequately explain the light-matter interaction in atomically thin crystals. In this paper, we examine the spin-orbit interaction on the surface of the freestanding atomically thin crystals. We find that it is not necessary to involve the effective refractive index to describe the spin-orbit interaction and the photonic SHE in the atomically thin crystals. The strong spin-orbit interaction and giant photonic SHE are predicted, which can be explained as the large polarization rotation of plane-wave components in order to satisfy the transversality of photon polarization.
Long-Range Corrected Hybrid Density Functionals with Damped Atom-Atom Dispersion Corrections
Energy Technology Data Exchange (ETDEWEB)
Chai, Jeng-Da; Head-Gordon, Martin
2008-06-14
We report re-optimization of a recently proposed long-range corrected (LC) hybrid density functionals [J.-D. Chai and M. Head-Gordon, J. Chem. Phys. 128, 084106 (2008)] to include empirical atom-atom dispersion corrections. The resulting functional, {omega}B97X-D yields satisfactory accuracy for thermochemistry, kinetics, and non-covalent interactions. Tests show that for non-covalent systems, {omega}B97X-D shows slight improvement over other empirical dispersion-corrected density functionals, while for covalent systems and kinetics, it performs noticeably better. Relative to our previous functionals, such as {omega}B97X, the new functional is significantly superior for non-bonded interactions, and very similar in performance for bonded interactions.
Engineering an atom-interferometer with modulated light-induced $3 \\pi$ spin-orbit coupling
Olson, Abraham J; Blasing, David B; Niffenegger, Robert J; Chen, Yong P
2015-01-01
We have developed an experimental method to modify the single-particle dispersion using periodic modulation of Raman beams which couple two spin-states of an ultracold atomic gas. The modulation introduces a new coupling between Raman-induced spin-orbit-coupled dressed bands, creating a second generation of dressed-state eigenlevels that feature both a novel 3{\\pi} spin-orbit coupling and a pair of avoided crossings, which is used to realize an atomic interferometer. The spin polarization and energies of these eigenlevels are characterized by studying the transport of a Bose-Einstein condensate in this system, including observing a Stueckelberg interference.
Lin, Lin
2012-01-01
We describe how to apply the recently developed pole expansion plus selected inversion (PEpSI) technique to Kohn-Sham density function theory (DFT) electronic structure calculations that are based on atomic orbital discretization. We give analytic expressions for evaluating charge density, total energy, Helmholtz free energy and atomic forces without using the eigenvalues and eigenvectors of the Kohn-Sham Hamiltonian. We also show how to update the chemical potential without using Kohn-Sham...
Quantum Spectra of Hydrogen Atoms in Various Magnetic Fields with the Closed Orbit Theory
Institute of Scientific and Technical Information of China (English)
彭良友; 张现周; 饶建国
2002-01-01
The quantum spectra of hydrogen atoms in various magnetic fields have been calculated with the closed orbit theory. The magnitude of the magnetic field decreases from 5.96 T to 0.56 T with a step of 0. 6 T. We demonstrate schematically that the closed orbits disappear with the decrease of the magnitude of the magnetic field when the corresponding finite resolution of experiment is fixed. This may give us a good way to control the shape and the number of the closed orbits in the system, and thus to control where a peak should exist in the Fourier transformation of the quantum spectra.
Spin-orbit-coupled two-electron Fermi gases of ytterbium atoms
Song, Bo; He, Chengdong; Zhang, Shanchao; Hajiyev, Elnur; Huang, Wei; Liu, Xiong-Jun; Jo, Gyu-Boong
2016-12-01
We demonstrate all-optical implementation of spin-orbit coupling (SOC) in a two-electron Fermi gas of 173Yb atoms by coupling two hyperfine ground states with a narrow optical transition. Due to the SU (N ) symmetry of the S10 ground-state manifold which is insensitive to external magnetic fields, an optical ac Stark effect is applied to split the ground spin states, which exhibits a high stability compared with experiments on alkali-metal and lanthanide atoms, and separate out an effective spin-1/2 subspace from other hyperfine levels for the realization of SOC. The dephasing spin dynamics when a momentum-dependent spin-orbit gap is suddenly opened and the asymmetric momentum distribution of the spin-orbit-coupled Fermi gas are observed as a hallmark of SOC. The realization of all-optical SOC for ytterbium fermions should offer a route to a long-lived spin-orbit-coupled Fermi gas and greatly expand our capability of studying spin-orbit physics with alkaline-earth-metal-like atoms.
Rechargeable Mg battery cathode TiS3 with d-p orbital hybridized electronic structures
Taniguchi, Kouji; Gu, Yunpeng; Katsura, Yukari; Yoshino, Takafumi; Takagi, Hidenori
2016-01-01
Rechargeable performance is realized in Mg batteries using a TiS3 cathode without the nanometer-scale downsizing of electrode particles. The specific capacity is about 80 mAh/g for the first 50 cycles at room temperature. This observed specific capacity is comparable to that of the prototype cathode for Mg batteries. First-principles calculation indicates that TiS3 is a semiconductor with d-p orbital hybridized electronic structures around the Fermi level. The reversible electrode performance is likely assisted by the delocalized electronic distribution over metal-ligand units through d-p orbital hybridization.
The Bohr Correspondence Principle: Kepler Orbits of the Electron in a Hydrogen Atom
Indian Academy of Sciences (India)
2016-06-01
We consider the quantum-mechanical non-relativistichydrogen atom. We show that for boundstates with size much larger than the Bohr radius,one can construct a wave packet that is localizedin space corresponding to a classical particlemoving in a circular orbit.
DEFF Research Database (Denmark)
Ruud, K.; Helgaker, T.; Jørgensen, Poul
1994-01-01
We report a systematic investigation of the magnetizability of a series of small molecules. The use of London atomic orbitals ensures gauge invariance and a fast basis set convergence. Good agreement is obtained with experimental magnetizabilities, both isotropic and anisotropic. The calculations...
Perturbative calculation of the Sternheimer anti-shielding factor with Hartree-Fock atomic orbitals
2012-01-01
We report a calculation of the Sternheimer anti-shielding factor, \\gamma, by means of first order perturbation theory. In quality of basis functions, we use Hartree-Fock electronic orbitals, expanded on hydrogenic atomic states. The computed \\gamma(r) for Fe^{3+} and Cu^{1+} inner electronic cores are reported and compared with literature values, obtained from alternative methodologies.
Energy Technology Data Exchange (ETDEWEB)
Thiele, Robert; Son, Sang-Kil [Center for Free-Electron Laser Science, DESY, 22607 Hamburg (Germany); Ziaja, Beata [Center for Free-Electron Laser Science, DESY, 22607 Hamburg (Germany); Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Krakow (Poland); Santra, Robin [Center for Free-Electron Laser Science, DESY, 22607 Hamburg (Germany); Department of Physics, University of Hamburg, 20355 Hamburg (Germany)
2013-07-01
X-ray free-electron lasers (XFELs) are a promising tool for the structural determination of macro- and biomolecules, using coherent diffractive imaging. During imaging, the intense XFEL pulses also efficiently ionize the molecules, so it is important to estimate how the charged environment within the molecule modifies atomic properties, in comparison to the case of an isolated atom. Here, we apply the XATOM toolkit to obtain predictions on the modified ionization thresholds and rates of some photoinduced processes in carbon. The Hartree-Fock-Slater model is extended to include the electron screening and ion correlation effects, induced by external charges. With this extended model, we obtain predictions on modifications of orbital energies, photoabsorption cross sections, Auger decay rates, fluorescence emission rates, and atomic scattering factors as a function of the density and temperature of the surrounding charges. Our results have implications for the studies of dynamics within XFEL irradiated samples, in particular for those dedicated to coherent diffraction imaging.
Origin of Perpendicular Magnetic Anisotropy and Large Orbital Moment in Fe Atoms on MgO.
Baumann, S; Donati, F; Stepanow, S; Rusponi, S; Paul, W; Gangopadhyay, S; Rau, I G; Pacchioni, G E; Gragnaniello, L; Pivetta, M; Dreiser, J; Piamonteze, C; Lutz, C P; Macfarlane, R M; Jones, B A; Gambardella, P; Heinrich, A J; Brune, H
2015-12-04
We report on the magnetic properties of individual Fe atoms deposited on MgO(100) thin films probed by x-ray magnetic circular dichroism and scanning tunneling spectroscopy. We show that the Fe atoms have strong perpendicular magnetic anisotropy with a zero-field splitting of 14.0±0.3 meV/atom. This is a factor of 10 larger than the interface anisotropy of epitaxial Fe layers on MgO and the largest value reported for Fe atoms adsorbed on surfaces. The interplay between the ligand field at the O adsorption sites and spin-orbit coupling is analyzed by density functional theory and multiplet calculations, providing a comprehensive model of the magnetic properties of Fe atoms in a low-symmetry bonding environment.
Origin of Perpendicular Magnetic Anisotropy and Large Orbital Moment in Fe Atoms on MgO
Baumann, S.; Donati, F.; Stepanow, S.; Rusponi, S.; Paul, W.; Gangopadhyay, S.; Rau, I. G.; Pacchioni, G. E.; Gragnaniello, L.; Pivetta, M.; Dreiser, J.; Piamonteze, C.; Lutz, C. P.; Macfarlane, R. M.; Jones, B. A.; Gambardella, P.; Heinrich, A. J.; Brune, H.
2015-12-01
We report on the magnetic properties of individual Fe atoms deposited on MgO(100) thin films probed by x-ray magnetic circular dichroism and scanning tunneling spectroscopy. We show that the Fe atoms have strong perpendicular magnetic anisotropy with a zero-field splitting of 14.0 ±0.3 meV /atom . This is a factor of 10 larger than the interface anisotropy of epitaxial Fe layers on MgO and the largest value reported for Fe atoms adsorbed on surfaces. The interplay between the ligand field at the O adsorption sites and spin-orbit coupling is analyzed by density functional theory and multiplet calculations, providing a comprehensive model of the magnetic properties of Fe atoms in a low-symmetry bonding environment.
The splitting of atomic orbitals with a common principal quantum number revisited: np vs. ns.
Katriel, Jacob
2012-04-14
Atomic orbitals with a common principal quantum number are degenerate, as in the hydrogen atom, in the absence of interelectronic repulsion. Due to the virial theorem, electrons in such orbitals experience equal nuclear attractions. Comparing states of several-electron atoms that differ by the occupation of orbitals with a common principal quantum number, such as 1s(2) 2s vs. 1s(2) 2p, we find that although the difference in energies, ΔE, is due to the interelectronic repulsion term in the Hamiltonian, the difference between the interelectronic repulsions, ΔC, makes a smaller contribution to ΔE than the corresponding difference between the nuclear attractions, ΔL. Analysis of spectroscopic data for atomic isoelectronic sequences allows an extensive investigation of these issues. In the low nuclear charge range of pertinent isoelectronic sequences, i.e., for neutral atoms and mildly positively charged ions, it is found that ΔC actually reverses its sign. About 96% of the nuclear attraction difference between the 6p (2)P and the 6s (2)S states of the Cs atom is cancelled by the corresponding interelectronic repulsion difference. From the monotonic increase of ΔE with Z it follows (via the Hellmann-Feynman theorem) that ΔL > 0. Upon increasing the nuclear charge along an atomic isoelectronic sequence with a single electron outside a closed shell from Z(c), the critical charge below which the outmost electron is not bound, to infinity, the ratio ΔC/ΔL increases monotonically from lim(Z→Z(c)(+))ΔC/ΔL=-1 to lim(Z→∞)ΔC/ΔL=1. These results should allow for a more nuanced discussion than is usually encountered of the crude electronic structure of many-electron atoms and the structure of the periodic table.
Zhao, Xin; Geskin, Victor; Stadler, Robert
2017-03-01
Destructive quantum interference (DQI) in single molecule electronics is a purely quantum mechanical effect and is entirely defined by the inherent properties of the molecule in the junction such as its structure and symmetry. This definition of DQI by molecular properties alone suggests its relation to other more general concepts in chemistry as well as the possibility of deriving simple models for its understanding and molecular device design. Recently, two such models have gained a wide spread attention, where one was a graphical scheme based on visually inspecting the connectivity of the carbon sites in conjugated π systems in an atomic orbital (AO) basis and the other one puts the emphasis on the amplitudes and signs of the frontier molecular orbitals (MOs). There have been discussions on the range of applicability for these schemes, but ultimately conclusions from topological molecular Hamiltonians should not depend on whether they are drawn from an AO or a MO representation, as long as all the orbitals are taken into account. In this article, we clarify the relation between both models in terms of the zeroth order Green's function and compare their predictions for a variety of systems. From this comparison, we conclude that for a correct description of DQI from a MO perspective, it is necessary to include the contributions from all MOs rather than just those from the frontier orbitals. The cases where DQI effects can be successfully predicted within a frontier orbital approximation we show them to be limited to alternant even-membered hydrocarbons, as a direct consequence of the Coulson-Rushbrooke pairing theorem in quantum chemistry.
Pardini, Lorenzo; Löffler, Stefan; Biddau, Giulio; Hambach, Ralf; Kaiser, Ute; Draxl, Claudia; Schattschneider, Peter
2016-07-15
Transmission electron microscopy has been a promising candidate for mapping atomic orbitals for a long time. Here, we explore its capabilities by a first-principles approach. For the example of defected graphene, exhibiting either an isolated vacancy or a substitutional nitrogen atom, we show that three different kinds of images are to be expected, depending on the orbital character. To judge the feasibility of visualizing orbitals in a real microscope, the effect of the optics' aberrations is simulated. We demonstrate that, by making use of energy filtering, it should indeed be possible to map atomic orbitals in a state-of-the-art transmission electron microscope.
A Novel Image Encryption Scheme Based on Multi-orbit Hybrid of Discrete Dynamical System
Directory of Open Access Journals (Sweden)
Ruisong Ye
2014-10-01
Full Text Available A multi-orbit hybrid image encryption scheme based on discrete chaotic dynamical systems is proposed. One generalized Arnold map is adopted to generate three orbits for three initial conditions. Another chaotic dynamical system, tent map, is applied to generate one pseudo-random sequence to determine the hybrid orbit points from which one of the three orbits of generalized Arnold map. The hybrid orbit sequence is then utilized to shuffle the pixels' positions of plain-image so as to get one permuted image. To enhance the encryption security, two rounds of pixel gray values' diffusion is employed as well. The proposed encryption scheme is simple and easy to manipulate. The security and performance of the proposed image encryption have been analyzed, including histograms, correlation coefficients, information entropy, key sensitivity analysis, key space analysis, differential analysis, etc. All the experimental results suggest that the proposed image encryption scheme is robust and secure and can be used for secure image and video communication applications.
Spin-orbit hybrid entanglement quantum key distribution scheme
Institute of Scientific and Technical Information of China (English)
ZHANG ChengXian; GUO BangHong; CHENG GuangMing; GUO JianJun; FAN RongHua
2014-01-01
We propose a novel quantum key distribution scheme by using the SAM-OAM hybrid entangled state as the physical resource.To obtain this state,the polarization entangled photon pairs are created by the spontaneous parametric down conversion process,and then,the q-plate acts as a SAM-to-OAM transverter to transform the polarization entangled pairs into the hybrid entangled pattern,which opens the possibility to exploit the features of the higher-dimensional space of OAM state to encode information.In the manipulation and encoding process,Alice performs the SAM measurement by modulating the polarization state |θ＞π on one photon,whereas Bob modulates the OAM sector state |x＞1 on the other photon to encode his key elements using the designed holograms which is implemented by the computer-controlled SLM.With coincidence measurement,Alice could extract the key information.It is showed that N-based keys can be encoded with each pair of entangled photon,and this scheme is robust against Eve's individual attack.Also,the MUBs are not used.Alice and Bob do not need the classical communication for the key recovery.
Efimov physics and universal trimers in spin-orbit-coupled ultracold atomic mixtures
Shi, Zhe-Yu; Zhai, Hui; Cui, Xiaoling
2015-02-01
We study the two-body and three-body bound states in ultracold atomic mixtures with one of the atoms subjected to an isotropic spin-orbit (SO) coupling. We consider a system of two identical fermions interacting with one SO-coupled atom. It is found that there can exist two types of three-body bound states, Efimov trimers and universal trimers. The Efimov trimers are energetically less favored by the SO coupling, which will finally merge into the atom-dimer threshold as increasing the SO-coupling strength. Nevertheless, these trimers exhibit a discrete scaling law incorporating the SO-coupling effect. On the other hand, the universal trimers are more favored by the SO coupling. They can be induced at negative s -wave scattering lengths and with smaller mass ratios than those without SO coupling. These results are obtained by both the Born-Oppenheimer approximation and exact solutions from three-body equations.
Goos-H\\"anchen shifts in spin-orbit-coupled cold atoms
Zhou, Lu; Qin, Jie-Li; Lan, Zhihao; Dong, Guangjiong; Zhang, Weiping
2014-01-01
We consider a matter wave packet of cold atom gas impinging upon a step potential created by the optical light field. In the presence of spin-orbit (SO) coupling, the atomic eigenstates contain two types of evanescent states, one of which is the ordinary evanescent state with pure imaginary wave vector while the other possesses complex wave vector and is recognized as oscillating evanescent state. We show that the presence and interplay of these two types of evanescent states can give rise to...
Electron dynamics in the carbon atom induced by spin-orbit interaction
Rey, H F
2014-01-01
We use R-Matrix theory with Time dependence (RMT) to investigate multiphoton ionization of ground-state atomic carbon with initial orbital magnetic quantum number $M_L$=0 and $M_L$=1 at a laser wavelength of 390 nm and peak intensity of 10$^{14}$ W cm$^{-2}$. Significant differences in ionization yield and ejected-electron momentum distribution are observed between the two values for $M_L$. We use our theoretical results to model how the spin-orbit interaction affects electron emission along the laser polarization axis. Under the assumption that an initial C atom is prepared at zero time delay with $M_L=0$, the dynamics with respect to time delay of an ionizing probe pulse modelled using RMT theory is found to be in good agreement with available experimental data.
Rey, H. F.; van der Hart, H. W.
2014-09-01
We use R-matrix theory with time dependence (RMT) to investigate multiphoton ionization of ground-state atomic carbon with initial orbital magnetic quantum number ML=0 and ML=1 at a laser wavelength of 390 nm and peak intensity of 1014W/cm2. Significant differences in ionization yield and ejected-electron momentum distribution are observed between the two values for ML. We use our theoretical results to model how the spin-orbit interaction affects electron emission along the laser polarization axis. Under the assumption that an initial C atom is prepared at zero time delay with ML=0, the dynamics with respect to time delay of an ionizing probe pulse modeled by using RMT theory is found to be in good agreement with available experimental data.
Institute of Scientific and Technical Information of China (English)
Guseinov I. Israfil; Erturk Murat
2008-01-01
Using complete orthonormal sets of Ψα -exponential type orbitals in single exponent approximation the new approach has been suggested for construction of different kinds of functions which can be useful in the theory of linear combination of atomic orbitals. These functions can be chosen properly according to the nature of the problems under consideration. This is rather important because the choice of the basis set may be play a crucial role in applications to atomic and molecular problems. As an example of application, different atomic orbitals for the ground states of the neutral and the first ten cationic members of the isoelectronic series of He atom are constructed by the solution of Hartree-Fock Roothaan equations using Ψ1, Ψ0 and Ψ-1 basis sets. The calculated results are close to the numerical Hartree-Fock values. The total energy, expansion coefficients, orbital exponents and virial ratio for each atom are presented.
Dynamics of atomic spin-orbit-state wave packets produced by short-pulse laser photodetachment
Law, S M K
2016-01-01
We analyse the experiment by Hultgren et al. [Phys. Rev. A {\\bf 87}, 031404 (2013)] on orbital alignment and quantum beats in coherently excited atomic fine-structure manifolds produced by short-pulse laser photodetachment of C$^-$, Si$^-$ and Ge$^-$ negative ions, and derive a formula that describes the beats. Analysis of the experimental data enables us to extract the non-coherent background contribution for each species, and indicates the need for a full density matrix treatment of the problem.
Search for Efimov trimers in ultracold atomic mixtures in the presence of spin-orbit coupling
Wang, Su-Ju; Han, Huili; Perez-Rios, Jesus; Greene, Chris
2015-05-01
Realization of synthetic gauge fields in ultracold atomic systems has attracted much attention in both few-body and many-body physics. Especially, there are extensive works on the two-body aspects of spin-orbit coupled quantum gases, which have already shown intriguing new features due to the change in the energy dispersion relation. However, there are few studies on the three-body physics in the presence of spin-orbit coupling. In this work, we apply the hyperspherical coordinate approach in the adiabatic approximation to solve the three-body system in zero total angular momentum subspace, where two of them are spin-orbit coupled, and the third one of a different species is not. Examination of the computed hyperspherical potential curves should provide the information needed to explore the possible existence of universal three-body bound states.
Thorvaldsen, Andreas J.; Ruud, Kenneth; Rizzo, Antonio; Coriani, Sonia
2008-10-01
We present the first gauge-origin-independent, frequency-dependent calculations of the hypermagnetizability anisotropy, which determines the temperature-independent contribution to magnetic-field-induced linear birefringence, the so-called Cotton-Mouton effect. A density-matrix-based scheme for analytical calculations of frequency-dependent molecular properties for self-consistent field models has recently been developed, which is also valid with frequency- and field-dependent basis sets. Applying this scheme to Hartree-Fock wave functions and using London atomic orbitals in order to obtain gauge-origin-independent results, we have calculated the hypermagnetizability anisotropy. Our results show that the use of London orbitals leads to somewhat better basis-set convergence for the hypermagnetizability compared to conventional basis sets and that London orbitals are mandatory in order to obtain reliable magnetizability anisotropies.
Cheng, Lan; Xiao, Yunlong; Liu, Wenjian
2009-12-28
It is recognized only recently that the incorporation of the magnetic balance condition is absolutely essential for four-component relativistic theories of magnetic properties. Another important issue to be handled is the so-called gauge problem in calculations of, e.g., molecular magnetic shielding tensors with finite bases. It is shown here that the magnetic balance can be adapted to distributed gauge origins, leading to, e.g., magnetically balanced gauge-including atomic orbitals (MB-GIAOs) in which each magnetically balanced atomic orbital has its own local gauge origin placed on its center. Such a MB-GIAO scheme can be combined with any level of theory for electron correlation. The first implementation is done here at the coupled-perturbed Dirac-Kohn-Sham level. The calculated molecular magnetic shielding tensors are not only independent of the choice of gauge origin but also converge rapidly to the basis set limit. Close inspections reveal that (zeroth order) negative energy states are only important for the expansion of first order electronic core orbitals. Their contributions to the paramagnetism are therefore transferable from atoms to molecule and are essentially canceled out for chemical shifts. This allows for simplifications of the coupled-perturbed equations.
Spin-orbit coupled two-electron Fermi gases of ytterbium atoms
Song, Bo; Zhang, Shanchao; Zou, Yueyang; Haciyev, Elnur; Huang, Wei; Liu, Xiong-Jun; Jo, Gyu-Boong
2016-01-01
We demonstrate the spin-orbit coupling (SOC) in a two-electron Fermi gas of $^{173}$Yb atoms by coupling two hyperfine ground states via the two-photon Raman transition. Due to the SU($N$) symmetry of the $^1$S$_0$ ground-state manifold which is insensitive to external magnetic field, an optical AC Stark effect is applied to split the ground spin states and separate an effective spin-1/2 subspace out from other hyperfine levels for the realization of SOC. With a momentum-dependent spin-orbit gap being suddenly opened by switching on the Raman transition, the dephasing of spin dynamics is observed, as a consequence of the momentum-dependent Rabi oscillations. Moreover, the momentum asymmetry of the spin-orbit coupled Fermi gas is also examined after projection onto the bare spin state and the corresponding momentum distribution is measured for different two-photon detuning. The realization of SOC for Yb fermions may open a new avenue to the study of novel spin-orbit physics with alkaline-earth-like atoms.
Explicitly correlated atomic orbital basis second order Møller-Plesset theory.
Hollman, David S; Wilke, Jeremiah J; Schaefer, Henry F
2013-02-14
The scope of problems treatable by ab initio wavefunction methods has expanded greatly through the application of local approximations. In particular, atomic orbital (AO) based wavefunction methods have emerged as powerful techniques for exploiting sparsity and have been applied to biomolecules as large as 1707 atoms [S. A. Maurer, D. S. Lambrecht, D. Flaig, and C. Ochsenfeld, J. Chem. Phys. 136, 144107 (2012)]. Correlated wavefunction methods, however, converge notoriously slowly to the basis set limit and, excepting the use of large basis sets, will suffer from a severe basis set incompleteness error (BSIE). The use of larger basis sets is prohibitively expensive for AO basis methods since, for example, second-order Møller-Plesset perturbation theory (MP2) scales linearly with the number of atoms, but still scales as O(N(5)) in the number of functions per atom. Explicitly correlated F12 methods have been shown to drastically reduce BSIE for even modestly sized basis sets. In this work, we therefore explore an atomic orbital based formulation of explicitly correlated MP2-F12 theory. We present working equations for the new method, which produce results identical to the widely used molecular orbital (MO) version of MP2-F12 without resorting to a delocalized MO basis. We conclude with a discussion of several possible approaches to a priori screening of contraction terms in our method and the prospects for a linear scaling implementation of AO-MP2-F12. The discussion includes concrete examples involving noble gas dimers and linear alkane chains.
Dynamics of Finite Energy Airy Beams Carrying Orbital Angular Momentum in Multilevel Atomic Vapors
Wu, Zhenkun; Wang, Shun; Hu, Weifei; Gu, Yuzong
2016-10-01
We numerically investigate the dynamics of inward circular finite-energy Airy beams carrying different orbital angular momentum (OAM) numbers in a close-Λ three-level atomic vapor with the electromagnetically induced transparency (EIT) window. We report that due to the EIT induced by the microwave field, the transverse intensity distribution properties of Airy beam can be feasibly manipulated and modulated through adjusting OAM numbers l and the frequency detuning, as well as the propagation distance, in the multi-level atomic systems. What's more, the rotation of the beam also can be observed with different positions in atomic ensembles. The investigation may provide a useful tool for studying particle manipulation, signal processing and propagation in graded-index (GRIN) fibers.
Goos-Hänchen shifts in spin-orbit-coupled cold atoms
Zhou, Lu; Qin, Jie-Li; Lan, Zhihao; Dong, Guangjiong; Zhang, Weiping
2015-03-01
We consider a matter wave packet of cold atom gas impinging upon a step potential created by an optical light field. In the presence of spin-orbit coupling, the atomic eigenstates contain two types of evanescent states, one of which is an ordinary evanescent state with a pure imaginary wave vector while the other possesses a complex wave vector and is recognized as an oscillating evanescent state. We show that the presence and interplay of these two types of evanescent states can give rise to two different mechanisms for total internal reflection, and thus lead to an unusual Goos-Hänchen (GH) effect. As a result, not only large positive but also large negative GH shifts can be observed in the reflected atomic beam. The dependence of the GH shift on the incident angle, energy, and height of the step potential is studied numerically.
2010-01-01
The transition in structure and composition across the titanium carbide /nickel hybrid interface has been determined at near atomic resolution by...coupling high-resolution transmission electron microscopy with three-dimensional atom probe tomography. The titanium carbide phase adopts a rocksalt-type
Application of Computational Intelligence in Order to Develop Hybrid Orbit Propagation Methods
Directory of Open Access Journals (Sweden)
Iván Pérez
2013-01-01
Full Text Available We present a new approach in astrodynamics and celestial mechanics fields, called hybrid perturbation theory. A hybrid perturbation theory combines an integrating technique, general perturbation theory or special perturbation theory or semianalytical method, with a forecasting technique, statistical time series model or computational intelligence method. This combination permits an increase in the accuracy of the integrating technique, through the modeling of higher-order terms and other external forces not considered in the integrating technique. In this paper, neural networks have been used as time series forecasters in order to help two economic general perturbation theories describe the motion of an orbiter only perturbed by the Earth’s oblateness.
Quantum State Transmission in a Superconducting Charge Qubit-Atom Hybrid.
Yu, Deshui; Valado, María Martínez; Hufnagel, Christoph; Kwek, Leong Chuan; Amico, Luigi; Dumke, Rainer
2016-12-06
Hybrids consisting of macroscopic superconducting circuits and microscopic components, such as atoms and spins, have the potential of transmitting an arbitrary state between different quantum species, leading to the prospective of high-speed operation and long-time storage of quantum information. Here we propose a novel hybrid structure, where a neutral-atom qubit directly interfaces with a superconducting charge qubit, to implement the qubit-state transmission. The highly-excited Rydberg atom located inside the gate capacitor strongly affects the behavior of Cooper pairs in the box while the atom in the ground state hardly interferes with the superconducting device. In addition, the DC Stark shift of the atomic states significantly depends on the charge-qubit states. By means of the standard spectroscopic techniques and sweeping the gate voltage bias, we show how to transfer an arbitrary quantum state from the superconducting device to the atom and vice versa.
Quantum State Transmission in a Superconducting Charge Qubit-Atom Hybrid
Yu, Deshui; Hufnagel, Christoph; Kwek, Leong Chuan; Amico, Luigi; Dumke, Rainer
2016-01-01
Hybrids consisting of macroscopic superconducting circuits and microscopic components, such as atoms and spins, have the potential of transmitting an arbitrary state between different quantum species, leading to the prospective of high-speed operation and long-time storage of quantum information. Here we propose a novel hybrid structure, where a neutral-atom qubit directly interfaces with a superconducting charge qubit, to implement the qubit-state transmission. The highly-excited Rydberg atom located inside the gate capacitor strongly affects the behavior of Cooper pairs in the box while the atom in the ground state hardly interferes with the superconducting device. In addition, the DC Stark shift of the atomic states significantly depends on the charge-qubit states. By means of the standard spectroscopic techniques and sweeping the gate voltage bias, we show how to transfer an arbitrary quantum state from the superconducting device to the atom and vice versa.
Ascertainment of the hybridization states of Fe atoms in austenite and martensite
Institute of Scientific and Technical Information of China (English)
孙振国; 刘志林; 李志林
1997-01-01
Based on Yu Ruihuang’s theory of electron structure calculation, applying the boundary condition that "the electron density of the contacting surface between atoms must be continuous" advanced by Cheng Kaijia, the hybridization states of Fec and Fef atoms in C-containing structure unit of austenite and FeⅠ, FeⅡ and FeⅢ atoms in C-containing unit of martensite are ascertained. The hybrid levels of Fec and Fef atoms in austenite are 13 and 14, respectively; and those of FeⅠ , FeⅡ and FeⅢ atoms are 12, 10 and 9, respectively. When the C content is low, the 11th, 10th and 9th levels are also the probable atom, state in martensite.
Hybrid statistics-simulations based method for atom-counting from ADF STEM images.
De Wael, Annelies; De Backer, Annick; Jones, Lewys; Nellist, Peter D; Van Aert, Sandra
2017-01-25
A hybrid statistics-simulations based method for atom-counting from annular dark field scanning transmission electron microscopy (ADF STEM) images of monotype crystalline nanostructures is presented. Different atom-counting methods already exist for model-like systems. However, the increasing relevance of radiation damage in the study of nanostructures demands a method that allows atom-counting from low dose images with a low signal-to-noise ratio. Therefore, the hybrid method directly includes prior knowledge from image simulations into the existing statistics-based method for atom-counting, and accounts in this manner for possible discrepancies between actual and simulated experimental conditions. It is shown by means of simulations and experiments that this hybrid method outperforms the statistics-based method, especially for low electron doses and small nanoparticles. The analysis of a simulated low dose image of a small nanoparticle suggests that this method allows for far more reliable quantitative analysis of beam-sensitive materials.
Cold atom-ion experiments in hybrid traps
Härter, Arne
2013-01-01
In the last 5 years, a novel field of physics and chemistry has developed in which cold trapped ions and ultracold atomic gases are brought into contact with each other. Combining ion traps with traps for neutral atoms yields a variety of new possibilities for research and experiments. These range from studies of cold atom-ion collisions and atom-ion chemistry to applications in quantum information science and condensed matter related research. In this article we give a brief introduction into this new field and describe some of the perspectives for its future development.
Institute of Scientific and Technical Information of China (English)
WANG De-Hua; LIN Sheng-Lu
2004-01-01
@@ We show how to extract the closed orbits from the quantum spectra data. According to the closed orbit theory,each closed orbit produces a sharp peak in the recurrence spectra of a non-hydrogenic atom in parallel electric and magnetic fields. For a given initial state, closed-orbit theory gives the dependence of this recurrence amplitude on the initial angle of an orbit. By comparing the recurrence amplitude for different initial states, we can determine the initial angles of the closed classical orbits from the quantum recurrence spectra. Therefore, by integrating the Hamiltonian motion equations, we can obtain the closed orbits directly. This method can also be used to extract the closed orbits from the experimental data.
Energy Technology Data Exchange (ETDEWEB)
Lin, Lin; Chen, Mohan; Yang, Chao; He, Lixin
2012-02-10
We describe how to apply the recently developed pole expansion plus selected inversion (PEpSI) technique to Kohn-Sham density function theory (DFT) electronic structure calculations that are based on atomic orbital discretization. We give analytic expressions for evaluating charge density, total energy, Helmholtz free energy and atomic forces without using the eigenvalues and eigenvectors of the Kohn-Sham Hamiltonian. We also show how to update the chemical potential without using Kohn-Sham eigenvalues. The advantage of using PEpSI is that it has a much lower computational complexity than that associated with the matrix diagonalization procedure. We demonstrate the performance gain by comparing the timing of PEpSI with that of diagonalization on insulating and metallic nanotubes. For these quasi-1D systems, the complexity of PEpSI is linear with respect to the number of atoms. This linear scaling can be observed in our computational experiments when the number of atoms in a nanotube is larger than a few hundreds. Both the wall clock time and the memory requirement of PEpSI is modest. This makes it even possible to perform Kohn-Sham DFT calculations for 10,000-atom nanotubes on a single processor. We also show that the use of PEpSI does not lead to loss of accuracy required in a practical DFT calculation.
Atomic Oxygen Interactions With Silicone Contamination on Spacecraft in Low Earth Orbit Studied
Banks, Bruce A.
2001-01-01
Silicones have been widely used on spacecraft as potting compounds, adhesives, seals, gaskets, hydrophobic surfaces, and atomic oxygen protective coatings. Contamination of optical and thermal control surfaces on spacecraft in low Earth orbit (LEO) has been an ever-present problem as a result of the interaction of atomic oxygen with volatile species from silicones and hydrocarbons onboard spacecraft. These interactions can deposit a contaminant that is a risk to spacecraft performance because it can form an optically absorbing film on the surfaces of Sun sensors, star trackers, or optical components or can increase the solar absorptance of thermal control surfaces. The transmittance, absorptance, and reflectance of such contaminant films seem to vary widely from very transparent SiOx films to much more absorbing SiOx-based films that contain hydrocarbons. At the NASA Glenn Research Center, silicone contamination that was oxidized by atomic oxygen has been examined from LEO spacecraft (including the Long Duration Exposure Facility and the Mir space station solar arrays) and from ground laboratory LEO simulations. The findings resulted in the development of predictive models that may help explain the underlying issues and effects. Atomic oxygen interactions with silicone volatiles and mixtures of silicone and hydrocarbon volatiles produce glassy SiOx-based contaminant coatings. The addition of hydrocarbon volatiles in the presence of silicone volatiles appears to cause much more absorbing (and consequently less transmitting) contaminant films than when no hydrocarbon volatiles are present. On the basis of the LDEF and Mir results, conditions of high atomic oxygen flux relative to low contaminant flux appear to result in more transparent contaminant films than do conditions of low atomic oxygen flux with high contaminant flux. Modeling predictions indicate that the deposition of contaminant films early in a LEO flight should depend much more on atomic oxygen flux than
Matzkin, A.; Dando, P. A.; Monteiro, T. S.
2003-02-01
In a previous work [Phys. Rev. A 66, 013410 (2002)], we noted a partial disagreement between quantum R matrix and semiclassical calculations of photoabsorption spectra of molecules in a magnetic field. We show that this disagreement is due to a nonvanishing contribution of processes, which are forbidden according to the usual semiclassical formalism. Formulas to include these processes are obtained by using a refined stationary phase approximation. The resulting higher order in ħ contributions also account for previously unexplained “recurrences without closed orbits.” Quantum and semiclassical photoabsorption spectra for Rydberg atoms and molecules in a magnetic field are calculated and compared to assess the validity of the first-order forbidden orbit contributions.
Matzkin, A; Monteiro, T S
2003-01-01
In a previous work [Phys. Rev. A \\textbf{66}, 0134XX (2002)] we noted a partial disagreement between quantum R-matrix and semiclassical calculations of photoabsorption spectra of molecules in a magnetic field. We show this disagreement is due to a non-vanishing contribution of processes which are forbidden according to the usual semiclassical formalism. Formulas to include these processes are obtained by using a refined stationary phase approximation. The resulting higher order in $\\hbar$ contributions also account for previously unexplained ``recurrences without closed-orbits''. Quantum and semiclassical photoabsorption spectra for Rydberg atoms and molecules in a magnetic field are calculated and compared to assess the validity of the first-order forbidden orbit contributions.
Zitterbewegung with spin-orbit coupled ultracold atoms in a fluctuating optical lattice
Argonov, V. Yu; Makarov, D. V.
2016-09-01
The dynamics of non-interacting ultracold atoms with artificial spin-orbit coupling is considered. Spin-orbit coupling is created using two moving optical lattices with orthogonal polarizations. Our main goal is to study influence of lattice noise on Rabi oscillations. Special attention is paid to the phenomenon of the Zitterbewegung being trembling motion caused by Rabi transitions between states with different velocities. Phase and amplitude fluctuations of lattices are modelled by means of the two-dimensional stochastic Ornstein-Uhlenbeck process, also known as harmonic noise. In the the noiseless case the problem is solved analytically in terms of the momentum representation. It is shown that lattice noise significantly extends duration of the Zitterbewegung as compared to the noiseless case. This effect originates from noise-induced decoherence of Rabi oscillations.
Linear scaling coupled cluster and perturbation theories in the atomic orbital basis
Scuseria, Gustavo E.; Ayala, Philippe Y.
1999-11-01
We present a reformulation of the coupled cluster equations in the atomic orbital (AO) basis that leads to a linear scaling algorithm for large molecules. Neglecting excitation amplitudes in a screening process designed to achieve a target energy accuracy, we obtain an AO coupled cluster method which is competitive in terms of number of amplitudes with the traditional molecular orbital (MO) solution, even for small molecules. For large molecules, the decay properties of integrals and excitation amplitudes becomes evident and our AO method yields a linear scaling algorithm with respect to molecular size. We present benchmark calculations to demonstrate that our AO reformulation of the many-body electron correlation problem defeats the "exponential scaling wall" that has characterized high-level MO quantum chemistry calculations for many years.
Atomic Gaussian type orbitals and their Fourier transforms via the Rayleigh expansion
Yükçü, Niyazi
2016-03-01
Gaussian type orbitals (GTOs), which are one of the types of exponential type orbitals (ETOs), are used usually as basis functions in the multi-center atomic and molecular integrals to better understand physical and chemical properties of matter. In the Fourier transform method (FTM), basis functions have not simplicity to make mathematical operations, but their Fourier transforms are easier to use. In this work, with the help of FTM, Rayleigh expansion and some properties of unnormalized GTOs, we present new mathematical results for the Fourier transform of GTOs in terms of Laguerre polynomials, hypergeometric and Whittaker functions. Physical and analytical properties of GTOs are discussed and some numerical results have been given in a table. Finally, we compare our mathematical results with the other known literature results by using a computer program and details of evaluation are presented.
Hübener, Hannes; Giustino, Feliciano
2014-02-01
We present the implementation of linear-response time-dependent density functional theory based on the self-consistent Sternheimer equation and employing a basis set of numerical pseudo-atomic orbitals. We demonstrate this method by presenting test calculations on systems of increasing size ranging from benzene to chlorophyll a, and by comparing our results with those obtained within Casida's formalism and with previous calculations. We provide a detailed assessment of the accuracy of this method, both in relation to the use of local orbitals for describing electronic excitations and to the handling of the frequency response using Padé approximants. We establish a simple criterion for estimating a priori the accuracy of the basis set in the calculation of optical spectra. We show that the computational cost of this method scales quadratically with the system size.
Graph of atomic orbitals and the molecular structure-descriptors based on it
Directory of Open Access Journals (Sweden)
ANDREY A. TOROPOV
2005-04-01
Full Text Available The graph of atomic orbitals (GAO is a novel type of molecular graph, recently proposed by one of the authors. Various molecular structure-descriptors computed for GAO are compared with their analogs computed for ordinary molecular graphs. The quality of these structure-descriptors was tested for correlation with the normal boiling points of alkanes and cycloalkanes. In all the studied cases, the results based on GAO are similar to, and usually slightly better than, those obtained by means of ordinary molecular graps.
Off-axis retrieval of orbital angular momentum of light stored in cold atoms
de Oliveira, R A; Barbosa, P S; Martins, W S; Barreiro, S; Felinto, D; Bloch, D; Tabosa, J W R
2014-01-01
We report on the storage of orbital angu- lar momentum (OAM) of light of a Laguerre-Gaussian mode in an ensemble of cold cesium atoms and its re- trieval along an axis different from the incident light beam. We employed a time-delayed four-wave mixing configuration to demonstrate that at small angle (2o), after storage, the retrieved beam carries the same OAM as the one encoded in the input beam. A calculation based on mode decomposition of the retrieved beam over the Laguerre-Gaussian basis is in agreement with the experimental observations done at small angle values. However, the calculation shows that the OAM retrieving would get lost at larger angles, reducing the fidelity of such storing-retrieving process. In addition, we have also observed that by applying an external magnetic field to the atomic ensemble the retrieved OAM presents Larmor oscillations, demonstrating the possibility of its manipulation and off-axis retrieval.
Lin, Lin; Yang, Chao; He, Lixin
2012-01-01
We describe how to apply the recently developed pole expansion plus selected inversion (PEpSI) technique to Kohn-Sham density function theory (DFT) electronic structure calculations that are based on atomic orbital discretization. We give analytic expressions for evaluating charge density, total energy, Helmholtz free energy and atomic forces without using the eigenvalues and eigenvectors of the Kohn-Sham Hamiltonian. We also show how to update the chemical potential without using Kohn-Sham eigenvalues. The advantage of using PEpSI is that it has a much lower computational complexity than that associated with the matrix diagonalization procedure. We demonstrate the performance gain by comparing the timing of PEpSI with that of diagonalization on insulating and metallic nanotubes. For these quasi-1D systems, the complexity of PEpSI is linear with respect to the number of atoms. This linear scaling can be observed in our computational experiments when the number of atoms in a nanotube is larger than a few hundr...
Energy Technology Data Exchange (ETDEWEB)
Koide, M. [Department of Science and Technology, Meisei University, Tokyo 191-8656 (Japan)]. E-mail: mkoide@galaxy.ocn.ne.jp; Koike, F. [School of Medicine, Kitasato University, Kanagawa 228-8555 (Japan); Azuma, Y. [PhotonFactory, IMSS, KEK, Ibaraki 305-0801 (Japan); Nagata, T. [Department of Science and Technology, Meisei University, Tokyo 191-8656 (Japan)
2005-06-15
We study the origin of dual window-type 3s->4p photoexcitation resonances of potassium atoms that have been observed previously [M. Koide et al., J. Phys. Soc. Jpn. 71 (2002) 1676] by means of photoion spectroscopy. We also consider the sub-valence shell photoexcitations of other alkali metal atoms. In potassium 3p photoionizations, the photoion energy levels may be labeled by their total angular momenta, and they are well separated due to the spin-orbit couplings in 3p subshells. The system of a photoion and a photoelectron is therefore a superposition of different total spin states if expressed in terms of the LS-coupling scheme. The ionization continuum may couple with several intermediate discrete states with different total spin quantum numbers, giving a possibility to observe split resonance structures in the spectra of 3s->np photoexcitations and in other alkali-atom photoexcitations. We discuss the dual window-type resonances in potassium, rubidium, and cesium atoms.
Hiberty, Philippe C.; Danovich, David; Shaik, Sason
2015-01-01
This commentary summarizes the authors' basic disagreements with the paper, "Rabbit-Ears, VSEPR Sterics, and Other Orbital Anachronisms," which criticizes the authors' usage of the hybrid orbitals for H[subscript 2]O in their book, "A Chemist's Guide to Valence Bond Theory" (Shaik and Hiberty, 2008). The current article shows…
Guseinov, I I
2010-01-01
The new combined formulas have been established for the complex and real rotation-angular functions arising in the evaluation of two-center overlap integrals over arbitrary atomic orbitals in molecular coordinate system. These formulas can be useful in the study of different quantum mechanical problems in both the theory and practice of calculations dealing with atoms, molecules, nuclei and solids when the integer and noninteger n complex and real atomic orbitals basis sets are emploed. This work presented the development of our previous paper (I.I. Guseinov, Phys. Rev. A, 32 (1985) 1864).
Institute of Scientific and Technical Information of China (English)
YUN Su-Jun; WANG Fu-He; ZHOU Yun-Song; DU Meng-Li
2007-01-01
We study the oscillations in the spontaneous emission rate of an atom near a dielectric slab. The emission rate is calculated as a function of system size using quantum electrodynamics. It exhibits multi-periodic oscillations.Four frequencies of the oscillations are extracted by Fourier transforms. They agree with actions of photon closed-orbits going away and returning to the atom. These oscillations are explained as manifestations of quantum interference effects between the emitted photon wave near the atom and the returning photon waves travelling along various closed-orbits.
Magnetic-field-mediated coupling and control in hybrid atomic-nanomechanical systems
Tretiakov, A
2016-01-01
Magnetically coupled hybrid quantum systems enable robust quantum state control through Landau-Zener transitions. Here, we show that an ultracold atomic sample coupled to a nanomechanical resonator via oscillating magnetic fields can be used to cool the resonator's mechanical motion, to measure the mechanical temperature, and to enable entanglement of these mesoscopic objects. We calculate the expected coupling for both permanent-magnet and current-conducting nanostring resonators and describe how this hybridization is attainable using recently developed fabrication techniques, including SiN nanostrings and atom chips.
Xu, Guochang
2008-01-01
This is the first book of the satellite era which describes orbit theory with analytical solutions of the second order with respect to all possible disturbances. Based on such theory, the algorithms of orbits determination are completely revolutionized.
Atomic Oxygen Erosion Yield Prediction for Spacecraft Polymers in Low Earth Orbit
Banks, Bruce A.; Backus, Jane A.; Manno, Michael V.; Waters, Deborah L.; Cameron, Kevin C.; deGroh, Kim K.
2009-01-01
The ability to predict the atomic oxygen erosion yield of polymers based on their chemistry and physical properties has been only partially successful because of a lack of reliable low Earth orbit (LEO) erosion yield data. Unfortunately, many of the early experiments did not utilize dehydrated mass loss measurements for erosion yield determination, and the resulting mass loss due to atomic oxygen exposure may have been compromised because samples were often not in consistent states of dehydration during the pre-flight and post-flight mass measurements. This is a particular problem for short duration mission exposures or low erosion yield materials. However, as a result of the retrieval of the Polymer Erosion and Contamination Experiment (PEACE) flown as part of the Materials International Space Station Experiment 2 (MISSE 2), the erosion yields of 38 polymers and pyrolytic graphite were accurately measured. The experiment was exposed to the LEO environment for 3.95 years from August 16, 2001 to July 30, 2005 and was successfully retrieved during a space walk on July 30, 2005 during Discovery s STS-114 Return to Flight mission. The 40 different materials tested (including Kapton H fluence witness samples) were selected specifically to represent a variety of polymers used in space as well as a wide variety of polymer chemical structures. The MISSE 2 PEACE Polymers experiment used carefully dehydrated mass measurements, as well as accurate density measurements to obtain accurate erosion yield data for high-fluence (8.43 1021 atoms/sq cm). The resulting data was used to develop an erosion yield predictive tool with a correlation coefficient of 0.895 and uncertainty of +/-6.3 10(exp -25)cu cm/atom. The predictive tool utilizes the chemical structures and physical properties of polymers to predict in-space atomic oxygen erosion yields. A predictive tool concept (September 2009 version) is presented which represents an improvement over an earlier (December 2008) version.
Superconducting Resonator-Rydberg Atom Hybrid in the Strong Coupling Regime
Yu, Deshui; Valado, Maria Martinez; Hufnagel, Christoph; Kwek, Leong Chuan; Amico, Luigi; Dumke, Rainer
2016-01-01
We propose a promising hybrid quantum system, where a highly-excited atom strongly interacts with a superconducting LC oscillator via the electric field of capacitor. An external electrostatic field is applied to tune the energy spectrum of atom. The atomic qubit is implemented by two eigenstates near an avoided-level crossing in the DC Stark map of Rydberg atom. Varying the electrostatic field brings the atomic-qubit transition on- or off-resonance to the microwave resonator, leading to a strong atom-resonator coupling with an extremely large cooperativity. Like the nonlinearity induced by Josephson junctions in superconducting circuits, the large atom-resonator interface disturbs the harmonic potential of resonator, resulting in an artificial two-level particle. Different universal two-qubit logic gates can also be performed on our hybrid system within the space where an atomic qubit couples to a single photon with an interaction strength much larger than any relaxation rates, opening the door to the cavity...
Superconducting resonator and Rydberg atom hybrid system in the strong coupling regime
Yu, Deshui; Landra, Alessandro; Valado, María Martínez; Hufnagel, Christoph; Kwek, Leong Chuan; Amico, Luigi; Dumke, Rainer
2016-12-01
We propose a promising hybrid quantum system, where a highly excited atom strongly interacts with a superconducting L C oscillator via the electric field of capacitor. An external electrostatic field is applied to tune the energy spectrum of the atom. The atomic qubit is implemented by two eigenstates near an avoided-level crossing in the dc Stark map of a Rydberg atom. Varying the electrostatic field brings the atomic-qubit transition on or off resonance with respect to the microwave resonator, leading to a strong atom-resonator coupling with an extremely large cooperativity. Like the nonlinearity induced by Josephson junctions in superconducting circuits, the large atom-resonator interface disturbs the harmonic potential of the resonator, resulting in an artificial two-level particle. Different universal two-qubit logic gates can also be performed on our hybrid system within the space where an atomic qubit couples to a single photon with an interaction strength much larger than any relaxation rates, opening the door to the cavity-mediated state transmission.
Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit
Bank, Bruce A.; de Groh, Kim K.; Backus, Jane A.
2008-01-01
A predictive tool was developed to estimate the low Earth orbit (LEO) atomic oxygen erosion yield of polymers based on the results of the Polymer Erosion and Contamination Experiment (PEACE) Polymers experiment flown as part of the Materials International Space Station Experiment 2 (MISSE 2). The MISSE 2 PEACE experiment accurately measured the erosion yield of a wide variety of polymers and pyrolytic graphite. The 40 different materials tested were selected specifically to represent a variety of polymers used in space as well as a wide variety of polymer chemical structures. The resulting erosion yield data was used to develop a predictive tool which utilizes chemical structure and physical properties of polymers that can be measured in ground laboratory testing to predict the in-space atomic oxygen erosion yield of a polymer. The properties include chemical structure, bonding information, density and ash content. The resulting predictive tool has a correlation coefficient of 0.914 when compared with actual MISSE 2 space data for 38 polymers and pyrolytic graphite. The intent of the predictive tool is to be able to make estimates of atomic oxygen erosion yields for new polymers without requiring expensive and time consumptive in-space testing.
The role of radial nodes of atomic orbitals for chemical bonding and the periodic table.
Kaupp, Martin
2007-01-15
The role of radial nodes, or of their absence, in valence orbitals for chemical bonding and periodic trends is discussed from a unified viewpoint. In particular, we emphasize the special role of the absence of a radial node whenever a shell with angular quantum number l is occupied for the first time (lack of "primogenic repulsion"), as with the 1s, 2p, 3d, and 4f shells. Although the consequences of the very compact 2p shell (e.g. good isovalent hybridization, multiple bonding, high electronegativity, lone-pair repulsion, octet rule) are relatively well known, it seems that some of the aspects of the very compact 3d shell in transition-metal chemistry are less well appreciated, e.g., the often weakened and stretched bonds at equilibrium structure, the frequently colored complexes, and the importance of nondynamical electron-correlation effects in bonding. Copyright (c) 2006 Wiley Periodicals, Inc.
Bzowski, M
2008-01-01
Contect: With the forthcoming launch of a NASA SMEX mission IBEX devoted to imaging of heliospheric interface by in-situ detection of Energetic Neutral Atoms (ENA) an important issue becomes recognizing of transport of these atoms from the termination shock of the solar wind to Earth orbit. Aims: Investigate modifications of energy and of survival probability of the H ENA detectable by IBEX (0.01 -- 6 keV) between the termination shock and Earth orbit taking into account the influence of the variable and anisotropic solar wind and solar EUV radiation. Methods: Energy change of the atoms is calculated by numerical simulations of orbits of the H ENA atoms from ~100 AU from the Sun down to Earth orbit, taking into account solar gravity and Lyman-$\\alpha$ radiation pressure, which is variable in time and depends on radial velocity of the atom. To calculate survival probabilities of the atoms against onization, a detailed 3D and time-dependent model of H ENA ionization based on observations of the solar wind and E...
Directory of Open Access Journals (Sweden)
Eduardo A. Castro
2004-12-01
Full Text Available We report the results of a calculation of the normal boiling points of a representative set of 200 organic molecules through the application of QSPR theory. For this purpose we have used a particular set of flexible molecular descriptors, the so called Correlation Weighting of Atomic Orbitals with Extended Connectivity of Zero- and First-Order Graphs of Atomic Orbitals. Although in general the results show suitable behavior to predict this physical chemistry property, the existence of some deviant behaviors points to a need to complement this index with some other sort of molecular descriptors. Some possible extensions of this study are discussed.
Mota,F.B.; Rivelino, R.; Medeiros, P.V.C.; Mascarenhas, A.J.S.; de Castilho, C. M. C.
2014-01-01
p.23558-23563 First-principles calculations demonstrate that line/ribbon defects, resulting from a controlled dehydrogenation in graphane, lead to the formation of low-dimensional electron-rich tracks in a monolayer. The present simulations point out that hybrid graphane–graphene nanostructures exhibit important elements, greatly required for the fabrication of efficient electronic circuits at the atomic level.
Atomic-scale photonic hybrids for mid-infrared and terahertz nanophotonics
Caldwell, Joshua D.; Vurgaftman, Igor; Tischler, Joseph G.; Glembocki, Orest J.; Owrutsky, Jeffrey C.; Reinecke, Thomas L.
2016-01-01
The field of nanophotonics focuses on the ability to confine light to nanoscale dimensions, typically much smaller than the wavelength of light. The goal is to develop light-based technologies that are impossible with traditional optics. Subdiffractional confinement can be achieved using either surface plasmon polaritons (SPPs) or surface phonon polaritons (SPhPs). SPPs can provide a gate-tunable, broad-bandwidth response, but suffer from high optical losses; whereas SPhPs offer a relatively low-loss, crystal-dependent optical response, but only over a narrow spectral range, with limited opportunities for active tunability. Here, motivated by the recent results from monolayer graphene and multilayer hexagonal boron nitride heterostructures, we discuss the potential of electromagnetic hybrids -- materials incorporating mixtures of SPPs and SPhPs -- for overcoming the limitations of the individual polaritons. Furthermore, we also propose a new type of atomic-scale hybrid the crystalline hybrid -- where mixtures of two or more atomic-scale (~3 nm or less) polar dielectric materials lead to the creation of a new material resulting from hybridized optic phonon behaviour of the constituents, potentially allowing direct control over the dielectric function. These atomic-scale hybrids expand the toolkit of materials for mid-infrared to terahertz nanophotonics and could enable the creation of novel actively tunable, yet low-loss optics at the nanoscale.
A Subfemtotesla Atomic Magnetometer Based on Hybrid Optical Pumping of Potassium and Rubidium
Li, Yang; Cai, Hongwei; Ding, Ming; Quan, Wei; Fang, Jiancheng
2016-05-01
Atomic magnetometers, based on detection of Larmor spin precession of optically pumped atoms, have been researched and applied extensively. Higher sensitivity and spatial resolution combined with no cryogenic cooling of atomic magnetometers would enable many applications with low cost, including the magnetoencephalography (MEG). Ultrahigh sensitivity atomic magnetometer is considered to be the main development direction for the future. Hybrid optical pumping has been proposed to improve the efficiency of nuclear polarization. But it can also be used for magnetic field measurement. This method can control absorption of optical pumping light, which is benefit for improving the uniformity of alkali metal atoms polarization and the sensitivity of atomic magnetometer. In addition, it allows optical pumping in the absence of quenching gas. We conduct experiments with a hybrid optically pumped atomic magnetometer using a cell containing potassium and rubidium. By adjusting the density ratio of alkali metal and the pumping laser conditions, we measured the magnetic field sensitivity better than 0.7 fT/sqrt(Hz).
Institute of Scientific and Technical Information of China (English)
Wang De-Hua
2007-01-01
Using the closed orbit theory,we study the classical motion and calculate the photoabsorption spectra of Rydberg hydrogen atom between two parallel metallic surfaces.The results show that the metallic surfaces have a significant effect on the photoabsorption process.When the distances between the hydrogen atom and the two metallic surfaces are close to a critical value dc,the number of the closed orbits is the greatest.When the distance larger or smaller than dc,the number of the closed orbits decreases and the absorption spectra are shown to exhibit a damping oscillation.This work is an interesting new application of closed-orbit theory and is of potential experimental interest.
Effects of losses in the atom-light hybrid SU(1,1) interferometer.
Chen, Zhao-Dan; Yuan, Chun-Hua; Ma, Hong-Mei; Li, Dong; Chen, L Q; Ou, Z Y; Zhang, Weiping
2016-08-08
Collective atomic excitation can be realized by the Raman scattering. Such a photon-atom interface can form an SU(1,1)-typed atom-light hybrid interferometer, where the atomic Raman amplification processes take the place of the beam splitting elements in a traditional Mach-Zehnder interferometer. We numerically calculate the phase sensitivities and the signal-to-noise ratios (SNRs) of this interferometer with the method of homodyne detection and intensity detection, and give their differences of the optimal phase points to realize the best phase sensitivities and the maximal SNRs from these two detection methods. The difference of the effects of loss of light field and atomic decoherence on measure precision is analyzed.
Emulating solid-state physics with a hybrid system of ultracold ions and atoms.
Bissbort, U; Cocks, D; Negretti, A; Idziaszek, Z; Calarco, T; Schmidt-Kaler, F; Hofstetter, W; Gerritsma, R
2013-08-23
We propose and theoretically investigate a hybrid system composed of a crystal of trapped ions coupled to a cloud of ultracold fermions. The ions form a periodic lattice and induce a band structure in the atoms. This system combines the advantages of high fidelity operations and detection offered by trapped ion systems with ultracold atomic systems. It also features close analogies to natural solid-state systems, as the atomic degrees of freedom couple to phonons of the ion lattice, thereby emulating a solid-state system. Starting from the microscopic many-body Hamiltonian, we derive the low energy Hamiltonian, including the atomic band structure, and give an expression for the atom-phonon coupling. We discuss possible experimental implementations such as a Peierls-like transition into a period-doubled dimerized state.
Intrinsic Atomic Orbitals: An Unbiased Bridge between Quantum Theory and Chemical Concepts.
Knizia, Gerald
2013-11-12
Modern quantum chemistry can make quantitative predictions on an immense array of chemical systems. However, the interpretation of those predictions is often complicated by the complex wave function expansions used. Here we show that an exceptionally simple algebraic construction allows for defining atomic core and valence orbitals, polarized by the molecular environment, which can exactly represent self-consistent field wave functions. This construction provides an unbiased and direct connection between quantum chemistry and empirical chemical concepts, and can be used, for example, to calculate the nature of bonding in molecules, in chemical terms, from first principles. In particular, we find consistency with electronegativities (χ), C 1s core-level shifts, resonance substituent parameters (σR), Lewis structures, and oxidation states of transition-metal complexes.
Bzowski, M.
2008-01-01
Context: With the forthcoming launch of a NASA SMEX mission IBEX devoted to imaging of heliospheric interface by in-situ detection of Energetic Neutral Atoms (ENA) an important issue becomes recognizing of transport of these atoms from the termination shock of the solar wind to Earth orbit. Aims: Investigate modifications of energy and of survival probability of the H ENA detectable by IBEX (0.01 -- 6 keV) between the termination shock and Earth orbit taking into account the influence of the ...
Weyl spin-orbit-coupling-induced interactions in uniform and trapped atomic quantum fluids
Gupta, Reena; Singh, G. S.; Bosse, Jürgen
2013-11-01
We establish through analytical and numerical studies of thermodynamic quantities for noninteracting atomic gases that the isotropic three-dimensional spin-orbit coupling, the Weyl coupling, induces interaction which counters “effective” attraction (repulsion) of the exchange symmetry present in zero-coupling Bose (Fermi) gas. The exact analytical expressions for the grand potential and hence for several thermodynamic quantities have been obtained for this purpose in both uniform and trapped cases. It is enunciated that many interesting features of spin-orbit-coupled systems revealed theoretically can be understood in terms of coupling-induced modifications in statistical interparticle potential. The temperature dependence of the chemical potential, specific heat, and isothermal compressibility for a uniform Bose gas is found to have signature of the incipient Bose-Einstein condensation in the very weak coupling regime although the system does not really go in the Bose-condensed phase. The transition temperature in the harmonically trapped case decreases with an increase of coupling strength consistent with the weakening of the statistical attractive interaction. Anomalous behavior of some thermodynamic quantities, partly akin to that in dimensions less than two, appears for uniform fermions as soon as the Fermi level goes down the Dirac point on increasing the coupling strength. It is suggested that the fluctuation-dissipation theorem can be utilized to verify anomalous behaviors from studies of long-wavelength fluctuations in bunching and antibunching effects.
Corsetti, Fabiano
2014-01-01
The implementation of the orbital minimization method (OMM) for solving the self-consistent Kohn-Sham (KS) problem for electronic structure calculations in a basis of non-orthogonal numerical atomic orbitals of finite-range is reported. We explore the possibilities for using the OMM as an exact cubic-scaling solver for the KS problem, and compare its performance with that of explicit diagonalization in realistic systems. We analyze the efficiency of the method depending on the choice of line search algorithm and on two free parameters, the scale of the kinetic energy preconditioning and the eigenspectrum shift. The results of several timing tests are then discussed, showing that the OMM can achieve a noticeable speedup with respect to diagonalization even for minimal basis sets for which the number of occupied eigenstates represents a significant fraction of the total basis size (>15%). We investigate the hard and soft parallel scaling of the method on multiple cores, finding a performance equal to or better ...
Global hybrids from the semiclassical atom theory satisfying the local density linear response
Fabiano, E; Cortona, P; Della Sala, F
2015-01-01
We propose global hybrid approximations of the exchange-correlation (XC) energy functional which reproduce well the modified fourth-order gradient expansion of the exchange energy in the semiclassical limit of many-electron neutral atoms and recover the full local density approximation (LDA) linear response. These XC functionals represent the hybrid versions of the APBE functional [Phys. Rev. Lett. 106, 186406, (2011)] yet employing an additional correlation functional which uses the localization concept of the correlation energy density to improve the compatibility with the Hartree-Fock exchange as well as the coupling-constant-resolved XC potential energy. Broad energetical and structural testings, including thermochemistry and geometry, transition metal complexes, non-covalent interactions, gold clusters and small gold-molecule interfaces, as well as an analysis of the hybrid parameters, show that our construction is quite robust. In particular, our testing shows that the resulting hybrid, including 20\\% o...
Rhile, Ian J.
2014-01-01
Atomic orbitals are a theme throughout the undergraduate chemistry curriculum, and visualizing them has been a theme in this journal. Contour plots as isosurfaces or contour lines in a plane are the most familiar representations of the hydrogen wave functions. In these representations, a surface of a fixed value of the wave function ? is plotted…
Universal quantum gates for photon-atom hybrid systems assisted by bad cavities.
Wang, Guan-Yu; Liu, Qian; Wei, Hai-Rui; Li, Tao; Ai, Qing; Deng, Fu-Guo
2016-01-01
We present two deterministic schemes for constructing a CNOT gate and a Toffoli gate on photon-atom and photon-atom-atom hybrid quantum systems assisted by bad cavities, respectively. They are achieved by cavity-assisted photon scattering and work in the intermediate coupling region with bad cavities, which relaxes the difficulty of their implementation in experiment. Also, bad cavities are feasible for fast quantum operations and reading out information. Compared with previous works, our schemes do not need any auxiliary qubits and measurements. Moreover, the schematic setups for these gates are simple, especially that for our Toffoli gate as only a quarter wave packet is used to interact the photon with each of the atoms every time. These atom-cavity systems can be used as the quantum nodes in long-distance quantum communication as their relatively long coherence time is suitable for multi-time operations between the photon and the system. Our calculations show that the average fidelities and efficiencies of our two universal hybrid quantum gates are high with current experimental technology.
Huang, Yongxian; Tian, Xiubo; Yang, Shiqin; Chu, Paul K
2007-10-01
A radio frequency (rf) inductively coupled plasma apparatus has been developed to simulate the atomic oxygen environment encountered in low Earth orbit (LEO). Basing on the novel design, the apparatus can achieve stable, long lasting operation, pure and high density oxygen plasma beam. Furthermore, the effective atomic oxygen flux can be regulated. The equivalent effective atomic oxygen flux may reach (2.289-2.984) x 10(16) at.cm(2) s at an oxygen pressure of 1.5 Pa and rf power of 400 W. The equivalent atomic oxygen flux is about 100 times than that in the LEO environment. The mass loss measured from the polyimide sample changes linearly with the exposure time, while the density of the eroded holes becomes smaller. The erosion mechanism of the polymeric materials by atomic oxygen is complex and involves initial reactions at the gas-surface interface as well as steady-state material removal.
External Heavy-Atom Effect via Orbital Interactions Revealed by Single-Crystal X-ray Diffraction.
Sun, Xingxing; Zhang, Baicheng; Li, Xinyang; Trindle, Carl O; Zhang, Guoqing
2016-07-28
Enhanced spin-orbit coupling through external heavy-atom effect (EHE) has been routinely used to induce room-temperature phosphorescence (RTP) for purely organic molecular materials. Therefore, understanding the nature of EHE, i.e., the specific orbital interactions between the external heavy atom and the luminophore, is of essential importance in molecular design. For organic systems, halogens (e.g., Cl, Br, and I) are the most commonly seen heavy atoms serving to realize the EHE-related RTP. In this report, we conduct an investigation on how heavy-atom perturbers and aromatic luminophores interact on the basis of data obtained from crystallography. We synthesized two classes of molecular systems including N-haloalkyl-substituted carbazoles and quinolinium halides, where the luminescent molecules are considered as "base" or "acid" relative to the heavy-atom perturbers, respectively. We propose that electron donation from a π molecular orbital (MO) of the carbazole to the σ* MO of the C-X bond (π/σ*) and n electron donation to a π* MO of the quinolinium moiety (n/π*) are responsible for the EHE (RTP) in the solid state, respectively.
Song, Chenchen; Martínez, Todd J.
2016-05-01
We present a tensor hypercontracted (THC) scaled opposite spin second order Møller-Plesset perturbation theory (SOS-MP2) method. By using THC, we reduce the formal scaling of SOS-MP2 with respect to molecular size from quartic to cubic. We achieve further efficiency by exploiting sparsity in the atomic orbitals and using graphical processing units (GPUs) to accelerate integral construction and matrix multiplication. The practical scaling of GPU-accelerated atomic orbital-based THC-SOS-MP2 calculations is found to be N2.6 for reference data sets of water clusters and alanine polypeptides containing up to 1600 basis functions. The errors in correlation energy with respect to density-fitting-SOS-MP2 are less than 0.5 kcal/mol for all systems tested (up to 162 atoms).
Liquid Water through Density-Functional Molecular Dynamics: Plane-Wave vs Atomic-Orbital Basis Sets
Miceli, Giacomo; Pasquarello, Alfredo
2016-01-01
We determine and compare structural, dynamical, and electronic properties of liquid water at near ambient conditions through density-functional molecular dynamics simulations, when using either plane-wave or atomic-orbital basis sets. In both frameworks, the electronic structure and the atomic forces are self-consistently determined within the same theoretical scheme based on a nonlocal density functional accounting for van der Waals interactions. The overall properties of liquid water achieved within the two frameworks are in excellent agreement with each other. Thus, our study supports that implementations with plane-wave or atomic-orbital basis sets yield equivalent results and can be used indiscriminately in study of liquid water or aqueous solutions.
Institute of Scientific and Technical Information of China (English)
WANG De-Hua
2010-01-01
@@ In a paper published by us,[1] we studied how to extract the closed orbit of the non-hydrogenic atom in parallel electric and magnetic fields. However, there was another paper published in 1996 by Courtney,[2] which studied the initial conditions of closed classical orbits from quantum spectra of hydrogen atom in magnetic field.
Multiple Majorana zero modes in atomic Fermi double wires with spin-orbit coupling
Wang, Liang-Liang; Gong, Ming; Liu, W.-M.
2017-08-01
Majorana zero modes, quasiparticles with non-Abelian statistics, have gained increasing interest for their fundamental role as building blocks in topological quantum computation. Previous studies have mainly focused on two well-separated Majorana zero modes, which could form two degenerate states serving as one nonlocal qubit for fault-tolerant quantum memory. However, creating and manipulating multiple Majorana zero modes, which could encode more qubits, remain an ongoing research topic. Here we report that multiple Majorana zero modes can exist in atomic Fermi double wires with spin-orbit coupling and perpendicular Zeeman field. This system belongs to the topological BDI class, thus all the topological superfluids are classified by integer numbers. Especially, diverse topological superfluids can be formed in a trap, where the zero energy modes can be found at the interfaces between different topological superfluids. The structure of these zero energy modes in the trap can be engineered by the trapping potential as well as other system parameters. This system would be a significant step towards utilization of Majorana zero modes in quantum computation.
Harding, Philip J; Mosk, Allard P; Vos, Willem L
2014-01-01
We study a hybrid system consisting of a narrowband atomic optical resonance and the long-range periodic order of an opaline photonic nanostructure. To this end, we have infiltrated atomic cesium vapor in a thin silica opal photonic crystal. With increasing temperature, the frequencies of the opal's reflectivity peaks shift down by >20% due to chemical reduction of the silica. Simultaneously, the photonic bands and gaps shift relative to the fixed near-infrared cesium D1 transitions. As a result the narrow atomic resonances with high finesse (f/df=8E5) dramatically change shape from a usual dispersive shape at the blue edge of a stop gap, to an inverted dispersion lineshape at the red edge of a stop gap. The lineshape, amplitude, and off-resonance reflectivity are well modeled with a transfer-matrix model that includes the dispersion and absorption of Cs hyperfine transitions and the chemically-reduced opal. An ensemble of atoms in a photonic crystal is an intriguing hybrid system that features narrow defect-...
Chemical Reaction of Ultracold Atoms and Ions in a Hybrid Trap
Rellergert, Wade G; Kotochigova, Svetlana; Petrov, Alexander; Chen, Kuang; Schowalter, Steven J; Hudson, Eric R
2011-01-01
Interactions between cold ions and atoms have been proposed for use in implementing quantum gates\\cite{Idziaszek2007}, probing quantum gases\\cite{Sherkunov2009}, observing novel charge-transport dynamics\\cite{Cote2000}, and sympathetically cooling atomic and molecular systems which cannot be laser cooled\\cite{Smith2005,Hudson2009}. Furthermore, the chemistry between cold ions and atoms is foundational to issues in modern astrophysics, including the formation of stars, planets, and interstellar clouds\\cite{Smith1992}, the diffuse interstellar bands\\cite{Reddy2010}, and the post-recombination epoch of the early universe\\cite{Stancil1996b}. However, as pointed out in refs 9 and 10, both experimental data and a theoretical description of the ion-atom interaction at low temperatures, reached in these modern atomic physics experiments and the interstellar environment, are still largely missing. Here we observe a chemical reaction between ultracold $^{174}$Yb$^+$ ions and $^{40}$Ca atoms held in a hybrid trap. We me...
Ultracold, radiative charge transfer in hybrid Yb ion - Rb atom traps
McLaughlin, B M; Lane, I C; McCann, J F
2014-01-01
Ultracold hybrid ion-atom traps offer the possibility of microscopic manipulation of quantum coherences in the gas using the ion as a probe. However, inelastic processes, particularly charge transfer can be a significant process of ion loss and has been measured experimentally for the Yb$^{+}$ ion immersed in a Rb vapour. We use first-principles quantum chemistry codes to obtain the potential energy curves and dipole moments for the lowest-lying energy states of this complex. Calculations for the radiative decay processes cross sections and rate coefficients are presented for the total decay processes. Comparing the semi-classical Langevin approximation with the quantum approach, we find it provides a very good estimate of the background at higher energies. The results demonstrate that radiative decay mechanisms are important over the energy and temperature region considered. In fact, the Langevin process of ion-atom collisions dominates cold ion-atom collisions. For spin dependent processes \\cite{kohl13} the...
Hybrid Quantum System of a Nanofiber Mode Coupled to Two Chains of Optically Trapped Atoms
Zoubi, Hashem
2010-01-01
A tapered optical nanofiber simultaneously used to trap and optically interface of cold atoms through evanescent fields constitutes a new and well controllable hybrid quantum system. The atoms are trapped in two parallel 1D optical lattices generated by suitable far blue and red detuned evanescent field modes very close to opposite sides of the nanofiber surface. Collective electronic excitations (excitons) of each of the optical lattices are resonantly coupled to the second lattice forming symmetric and antisymmetric common excitons. In contrast to the inverse cube dependence of the individual atomic dipole-dipole interaction, we analytically find an exponentially decaying coupling strength with distance between the lattices. The resulting symmetric (bright) excitons strongly interact with the resonant nanofiber photons to form fiber polaritons, which can be observed through linear optical spectra. For large enough wave vectors the polariton decay rate to free space is strongly reduced, which should render t...
Agapito, Luis; Calzolari, Arrigo; Ferretti, Andrea; Nardelli, Marco
2013-03-01
Metal-organic frameworks (MOF) are a new class of artificial crystalline materials. Because of their flexibility for synthesis and instrinsic ultrahigh surface area and porosity, MOFs show superior performance in gas storage, catalysis, and sensing applications. We use an efficient projection of plane-wave wavefunctions onto atomic orbitals for studying the electronic properties of these intriguing materials. The present scheme harnesses the robust periodic algorithms and systematic convergence of the plane-wave method for an atomistic electronic (Landauer conductance) and chemical (charge transfer, bond and atomic charge) analysis that provides guidelines for the design of MOF electronic materials.
Xiong, Xiao-Gen; Yanai, Takeshi
2017-07-11
The Projector Augmented Wave (PAW) method developed by Blöchl is well recognized as an efficient, accurate pseudopotential approach in solid-state density functional theory (DFT) calculations with the plane-wave basis. Here we present an approach to incorporate the PAW method into the Gauss-type function (GTF) based DFT implementation, which is widely used for molecular quantum chemistry calculations. The nodal and high-exponent GTF components of valence molecular orbitals (MOs) are removed or pseudized by the ultrasoft PAW treatment, while there is elaborate transparency to construct an accurate and well-controlled pseudopotential from all-electron atomic description and to reconstruct an all-electron form of valence MOs from the pseudo MOs. The smoothness of the pseudo MOs should benefit the efficiency of GTF-based DFT calculations in terms of elimination of high-exponent primitive GTFs and reduction of grid points in the numerical quadrature. The processes of the PAW method are divided into basis-independent and -dependent parts. The former is carried out using the previously developed PAW libraries libpaw and atompaw. The present scheme is implemented by incorporating libpaw into the conventional GTF-based DFT solver. The details of the formulations and implementations of GTF-related PAW procedures are presented. The test calculations are shown for illustrating the performance. With the near-complete GTF basis at the cc-pVQZ level, the total energies obtained using our PAW method with suited frozen core treatments converge to those with the conventional all-electron GTF-based method with a rather small absolute error.
Isaev, L.; Schachenmayer, J.; Rey, A. M.
2016-09-01
We show that an interplay between quantum effects, strong on-site ferromagnetic exchange interaction, and antiferromagnetic correlations in Kondo lattices can give rise to an exotic spin-orbit coupled metallic state in regimes where classical treatments predict a trivial insulating behavior. This phenomenon can be simulated with ultracold alkaline-earth fermionic atoms subject to a laser-induced magnetic field by observing dynamics of spin-charge excitations in quench experiments.
Isaev, L; Schachenmayer, J; Rey, A M
2016-09-23
We show that an interplay between quantum effects, strong on-site ferromagnetic exchange interaction, and antiferromagnetic correlations in Kondo lattices can give rise to an exotic spin-orbit coupled metallic state in regimes where classical treatments predict a trivial insulating behavior. This phenomenon can be simulated with ultracold alkaline-earth fermionic atoms subject to a laser-induced magnetic field by observing dynamics of spin-charge excitations in quench experiments.
Wang, Yueming; Liu, Bin; Lian, Jinling; Liang, Jiuqing
2012-04-23
We proposed a scheme for detecting the atom-field coupling constant in the Dicke superradiation regime based on a hybrid cavity optomechanical system assisted by an atomic gas. The critical behavior of the Dicke model was obtained analytically using the spin-coherent-state representation. Without regard to the dynamics of cavity field an analytical formula of one-to-one correspondence between movable mirror's steady position and atom-field coupling constant for a given number of atoms is obtained. Thus the atom-field coupling constant can be probed by measuring the movable mirror's steady position, which is another effect of the cavity optomechanics. © 2012 Optical Society of America
Compact quantum gates for hybrid photon-atom systems assisted by Faraday rotation
Song, Guo-Zhu; Yang, Guo-Jian; Zhang, Mei
2017-02-01
We present some compact circuits for a deterministic quantum computing on the hybrid photon-atom systems, including the Fredkin gate and SWAP gate. These gates are constructed by exploiting the optical Faraday rotation induced by an atom trapped in a single-sided optical microcavity. The control qubit of our gates is encoded on the polarization states of the single photon, and the target qubit is encoded on the ground states of an atom confined in an optical microcavity. Since the decoherence of the flying qubit with atmosphere for a long distance is negligible and the stationary qubits are trapped inside single-sided microcavities, our gates are robust. Moreover, ancillary single photon is not needed and only some linear-optical devices are adopted, which makes our protocols efficient and practical. Our schemes need not meet the condition that the transmission for the uncoupled cavity is balanceable with the reflectance for the coupled cavity, which is different from the quantum computation with a double-sided optical microcavity. Our calculations show that the fidelities of the two hybrid quantum gates are high with the available experimental technology.
Energy Technology Data Exchange (ETDEWEB)
Lindfors-Vrejoiu, Ionela; Engelmayer, Johannes; Loosdrecht, Paul H.M. van [II. Physikalisches Institut, Koeln Univ. (Germany); Jin, Lei; Jia, Chun-Lin [Peter Gruenberg Institut (PGI-5) and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Juelich GmbH (Germany); Himcinschi, Cameliu [Institut fuer Theoretische Physik, TU Bergakademie Freiberg (Germany); Hensling, Felix; Waser, Rainer; Dittmann, Regina [Peter Gruenberg Institut (PGI-7), Forschungszentrum Juelich GmbH (Germany)
2017-03-15
Orbital ordering has been less investigated in epitaxial thin films, due to the difficulty to evidence directly the occurrence of this phenomenon in thin film samples. Atomic resolution electron microscopy enabled us to observe the structural details of the ultrathin LaVO{sub 3} films. The transition to orbital ordering of epitaxial layers as thin as ∼4 nm was probed by temperature-dependent Raman scattering spectroscopy of multilayer samples. From the occurrence and temperature dependence of the 700 cm{sup -1} Raman active mode it can be inferred that the structural phase transition associated with orbital ordering takes place in ultrathin LaVO{sub 3} films at about 130 K. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Controllable growth and characterizations of hybrid spiral-like atomically thin molybdenum disulfide
Hao, Song; Yang, Bingchu; Gao, Yongli
2016-10-01
Monolayer MoS2 is an emerging two-dimensional semiconductor with wide-ranging potential applications in novel electronic and optoelectronic devices. Here, we reported controlled vapor phase growth of hybrid spiral-like MoS2 crystals investigated by multiple means of X-Ray photoemission spectroscopy, scanning electron microscopy, atomic force microscopy, kelvin probe force microscopy, Raman and Photoluminescence techniques. Morphological characterizations reveal an intriguing hybrid spiral-like MoS2 feature whose lower planes are AB Bernal stacking and upper structure is spiral. We ascribe the hybrid spiral-like structure to a screw dislocation drive growth mechanism owing to lower supersaturation and layer-by-layer growth mode. In addition, the electrostatic properties of MoS2 microflakes with hybrid spiral structures are obvious inhomogeneous and dependent on morphology manifested by kelvin probe force microscopy. Our work deepens the understanding of growth mechanisms of CVD-grown MoS2, which is also adoptable to other TMDC materials.
Fauché, Pierre; Kosionis, Spyridon G.; Lalanne, Philippe
2017-05-01
There is considerable interest in collective effects in hybrid systems formed by molecular or atomic ensembles strongly coupled by an electromagnetic resonance. For analyzing such collective effects, we develop an efficient and general theoretical formalism based on the natural modes of the resonator. The main strength of our approach is its generality and the high level of analyticity enabled by modal analysis, which allows one to model complex hybrid systems without any restriction on the resonator shapes or material properties, and to perform statistical computations to predict general properties that are robust to spatial and polarization disorders. Most notably, we establish that super-radiant modes remain even after ensemble averaging and act as an "invisibility cloak" with a spectral bandwidth that scales with the number of oscillators and the spatially averaged Purcell factor.
Meng, Kangkang; Xiao, Jiaxing; Wu, Yong; Miao, Jun; Xu, Xiaoguang; Zhao, Jianhua; Jiang, Yong
2016-02-04
The hybrid magnetoresistance (MR) behaviors in Pt/Co90Fe10/Pt, Mn1.5Ga/Pt and Mn1.5Ga/Pt/Co90Fe10/Pt multilayers have been investigated. Both planer Hall effect (PHE) and angle-dependent MR in Pt/Co90Fe10/Pt revealed the combination of spin Hall MR (SMR) and normal anisotropic MR (AMR), indicating the large contribution of strong spin-orbit coupling (SOC) at the interfaces. When Pt contacted with perpendicular magnetic anisotropy (PMA) metal Mn1.5Ga, the strong interfacial SOC modified the effective anomalous Hall effect. The MR in Mn1.5Ga/Pt/Co90Fe10/Pt is not a simple combination of SMR and AMR, but ascribed to the complicated domain wall scattering and strong interfacial SOC when Pt is sandwiched by the in-plane magnetized Co90Fe10 and the PMA Mn1.5Ga.
Bathen, Marianne Etzelmüller; Linder, Jacob
2017-01-01
We theoretically consider the spin Seebeck effect, the charge Seebeck coefficient, and the thermoelectric figure of merit in superconducting hybrid structures including either magnetic textures or intrinsic spin-orbit coupling. We demonstrate that large magnitudes for all these quantities are obtainable in Josephson-based systems with either zero or a small externally applied magnetic field. This provides an alternative to the thermoelectric effects generated in high-field (~1 T) superconducting hybrid systems, which were recently experimentally demonstrated. The systems studied contain either conical ferromagnets, spin-active interfaces, or spin-orbit coupling. We present a framework for calculating the linear thermoelectric response for both spin and charge of a system upon applying temperature and voltage gradients based on quasiclassical theory which allows for arbitrary spin-dependent textures and fields to be conveniently incorporated.
Selvaraj, Sathees Kannan; Jursich, Gregory; Takoudis, Christos G
2013-09-01
We report the development of a novel portable atomic layer deposition chemical vapor deposition (ALD/CVD) hybrid reactor setup. Unique feature of this reactor is the use of ALD/CVD mode in a single portable deposition system to fabricate multi-layer thin films over a broad range from "bulk-like" multi-micrometer to nanometer atomic dimensions. The precursor delivery system and control-architecture are designed so that continuous reactant flows for CVD and cyclic pulsating flows for ALD mode are facilitated. A custom-written LabVIEW program controls the valve sequencing to allow synthesis of different kinds of film structures under either ALD or CVD mode or both. The entire reactor setup weighs less than 40 lb and has a relatively small footprint of 8 × 9 in., making it compact and easy for transportation. The reactor is tested in the ALD mode with titanium oxide (TiO2) ALD using tetrakis(diethylamino)titanium and water vapor. The resulting growth rate of 0.04 nm/cycle and purity of the films are in good agreement with literature values. The ALD/CVD hybrid mode is demonstrated with ALD of TiO2 and CVD of tin oxide (SnOx). Transmission electron microscopy images of the resulting films confirm the formation of successive distinct TiO2-ALD and SnO(x)-CVD layers.
Selvaraj, Sathees Kannan; Jursich, Gregory; Takoudis, Christos G.
2013-09-01
We report the development of a novel portable atomic layer deposition chemical vapor deposition (ALD/CVD) hybrid reactor setup. Unique feature of this reactor is the use of ALD/CVD mode in a single portable deposition system to fabricate multi-layer thin films over a broad range from "bulk-like" multi-micrometer to nanometer atomic dimensions. The precursor delivery system and control-architecture are designed so that continuous reactant flows for CVD and cyclic pulsating flows for ALD mode are facilitated. A custom-written LabVIEW program controls the valve sequencing to allow synthesis of different kinds of film structures under either ALD or CVD mode or both. The entire reactor setup weighs less than 40 lb and has a relatively small footprint of 8 × 9 in., making it compact and easy for transportation. The reactor is tested in the ALD mode with titanium oxide (TiO2) ALD using tetrakis(diethylamino)titanium and water vapor. The resulting growth rate of 0.04 nm/cycle and purity of the films are in good agreement with literature values. The ALD/CVD hybrid mode is demonstrated with ALD of TiO2 and CVD of tin oxide (SnOx). Transmission electron microscopy images of the resulting films confirm the formation of successive distinct TiO2-ALD and SnOx-CVD layers.
Directory of Open Access Journals (Sweden)
Xiaotang Hu
2011-12-01
Full Text Available A hybrid atomic force microscopic (AFM measurement system combined with white light scanning interferometry for micro/nanometer dimensional measurement is developed. The system is based on a high precision large-range positioning platform with nanometer accuracy on which a white light scanning interferometric module and an AFM head are built. A compact AFM head is developed using a self-sensing tuning fork probe. The head need no external optical sensors to detect the deflection of the cantilever, which saves room on the head, and it can be directly fixed under an optical microscopic interferometric system. To enhance the system’s dynamic response, the frequency modulation (FM mode is adopted for the AFM head. The measuring data can be traceable through three laser interferometers in the system. The lateral scanning range can reach 25 mm × 25 mm by using a large-range positioning platform. A hybrid method combining AFM and white light scanning interferometry is proposed to improve the AFM measurement efficiency. In this method, the sample is measured firstly by white light scanning interferometry to get an overall coarse morphology, and then, further measured with higher resolution by AFM. Several measuring experiments on standard samples demonstrate the system’s good measurement performance and feasibility of the hybrid measurement method.
DataBus-based hybrid routing approach for orbit access networks in lunar exploration
Zeng, Hui; Meng, Ke; Deng, Julia
2012-06-01
One of the major challenges for lunar exploration missions is how to achieve dynamic and robust routing. To reduce the development cost, it is desirable to leverage existing technologies, such as routing in mobile ad hoc networks (MANETs) and delay tolerant networks (DTN). However, these technologies are developed for the Earth environment and hence need further investigation for the lunar environment. To support robust access and dynamic mission operations, we propose a DataBus-based Hybrid Routing (DBHR) approach that combines MANET reactive routing protocol (such as AODV) and DTN-based bundle delivery. Our DBHR approach is designed for a tiered architecture where remote nodes communicate with upper-tier gateways through data carriers (DataBus) using short-range radio interfaces. Our scheme explores the (non)availability of the end-to-end path between two peers using MANET routing and provides diverse route options based upon different parameters. This interaction between hop-by-hop DTN technologies and end-to-end MANET protocol will result in a reliable and robust routing protocol for orbit access and improve the overall communication capabilities. To evaluate its performance, we implemented our proposed scheme on commercial-off-theshelf (COTS) routers with the custom OpenWRT and tailored IBR-DTN bundle protocol distribution. The on-demand service request and grant mechanisms are also developed in our implementation to allow certain DTN nodes to reserve the future access opportunities. Finally, we demonstrate the achieved capabilities and performance gains through experiments on a hardware test bed that consists of several COTS routers with our implementation.
Spin-orbit and rotational couplings in radiative association of C(3P) and N(4S) atoms.
Antipov, Sergey V; Gustafsson, Magnus; Nyman, Gunnar
2011-11-14
The role of spin-orbit and rotational couplings in radiative association of C((3)P) and N((4)S) atoms is investigated. Couplings among doublet electronic states of the CN radical are considered, giving rise to a 6-state model of the process. The solution of the dynamical problem is based on the L(2) method, where a complex absorbing potential is added to the Hamiltonian operator in order to treat continuum and bound levels in the same manner. Comparison of the energy-dependent rate coefficients calculated with and without spin-orbit and rotational couplings shows that the couplings have a strong effect on the resonance structure and low-energy baseline of the rate coefficient.
Phillips, Patrick J.; Rui, Xue; Georgescu, Alexandru B.; Disa, Ankit S.; Longo, Paolo; Okunishi, Eiji; Walker, Fred; Ahn, Charles H.; Ismail-Beigi, Sohrab; Klie, Robert F.
2017-05-01
Epitaxial strain, layer confinement, and inversion symmetry breaking have emerged as powerful new approaches to control the electronic and atomic-scale structural properties of complex metal oxides. Trivalent rare-earth (RE) nickelate R E NiO3 heterostructures have been shown to be exemplars since the orbital occupancy, degeneracy, and, consequently, electronic/magnetic properties can be altered as a function of epitaxial strain, layer thickness, and superlattice structure. One recent example is the tricomponent LaTiO3-LaNiO3-LaAlO3 superlattice which exhibits charge transfer and orbital polarization as the result of its interfacial dipole electric field. A crucial step towards control of these parameters for future electronic and magnetic device applications is to develop an understanding of both the magnitude and range of the octahedral network's response towards interfacial strain and electric fields. An approach that provides atomic-scale resolution and sensitivity towards the local octahedral distortions and orbital occupancy is therefore required. Here, we employ atomic-resolution imaging coupled with electron spectroscopies and first-principles theory to examine the role of interfacial charge transfer and symmetry breaking in a tricomponent nickelate superlattice system. We find that nearly complete charge transfer occurs between the LaTiO3 and LaNiO3 layers, resulting in a mixed Ni2 +/Ni3 + valence state. We further demonstrate that this charge transfer is highly localized with a range of about 1 unit cell within the LaNiO3 layers. We also show how Wannier-function-based electron counting provides a simple physical picture of the electron distribution that connects directly with formal valence charges. The results presented here provide important feedback to synthesis efforts aimed at stabilizing new electronic phases that are not accessible by conventional bulk or epitaxial film approaches.
Directory of Open Access Journals (Sweden)
Yosuke Ito
2012-09-01
Full Text Available We have developed an optically pumped atomic magnetometer using a hybrid cell of K and Rb. The hybrid optical pumping technique can apply dense alkali-metal vapor to the sensor head and leads to high signal intensity. We use dense Rb vapor as probed atoms, and achieve a sensitivity of approximately 100 fTrms/Hz1/2 around 10 Hz. In this case, the sensitivity is limited by the system noise, and the magnetic linewidth is narrower than that for direct Rb optical pumping. We demonstrated magnetocardiography using the magnetometer and obtained clear human magnetocardiograms.
The atomic structure of ternary amorphous TixSi1-xO2 hybrid oxides.
Landmann, M; Köhler, T; Rauls, E; Frauenheim, T; Schmidt, W G
2014-06-25
Atomic length-scale order characteristics of binary and ternary amorphous oxides are presented within the framework of ab initio theory. A combined numerically efficient density functional based tight-binding molecular dynamics and density functional theory approach is applied to model the amorphous (a) phases of SiO2 and TiO2 as well as the amorphous phase of atomically mixed TixSi1-xO2 hybrid-oxide alloys over the entire composition range. Short and mid-range order in the disordered material phases are characterized by bond length and bond-angle statistics, pair distribution function analysis, coordination number and coordination polyhedra statistics, as well as ring statistics. The present study provides fundamental insights into the order characteristics of the amorphous hybrid-oxide frameworks formed by versatile types of TiOn and SiOm coordination polyhedra. In a-SiO2 the fourfold crystal coordination of Si ions is almost completely preserved and the atomic structure is widely dominated by ring-like mid-range order characteristics. In contrast, the structural disorder of a-TiO2 arises from short-range disorder in the local coordination environment of the Ti ion. The coordination number analysis indicates a large amount of over and under-coordinated Ti ions (coordination defects) in a-TiO2. Aside from the ubiquitous distortions of the crystal-like coordinated polyhedra, even the basic coordination-polyhedra geometry type changes for a significant fraction of TiO6 units (geometry defects). The combined effects of topological and chemical disorder in a-TixSi1-xO2 alloys lead to a continuos increase in both the Si as well as the Ti coordination number with the chemical composition x. The important roles of intermediate fivefold coordination states of Ti and Si cations are highlighted for ternary a-TixSi1-xO2 as well as for binary a-TiO2. The continuous decrease in ring size with increasing Ti content reflects the progressive loss of mid-range order structure
Ji, Wen-Xin; Xu, Wei; Schwarz, W H Eugen; Wang, Shu-Guang
2015-03-15
Lanthanide trihalide molecules LnX3 (X = F, Cl, Br, I) were quantum chemically investigated, in particular detail for Ln = Lu (lutetium). We applied density functional theory (DFT) at the nonrelativistic and scalar and SO-coupled relativistic levels, and also the ab initio coupled cluster approach. The chemically active electron shells of the lanthanide atoms comprise the 5d and 6s (and 6p) valence atomic orbitals (AO) and also the filled inner 4f semivalence and outer 5p semicore shells. Four different frozen-core approximations for Lu were compared: the (1s(2) -4d(10) ) [Pd] medium core, the [Pd+5s(2) 5p(6) = Xe] and [Pd+4f(14) ] large cores, and the [Pd+4f(14) +5s(2) 5p(6) ] very large core. The errors of LuX bonding are more serious on freezing the 5p(6) shell than the 4f(14) shell, more serious upon core-freezing than on the effective-core-potential approximation. The LnX distances correlate linearly with the AO radii of the ionic outer shells, Ln(3+) -5p(6) and X(-) -np(6) , characteristic for dominantly ionic Ln(3+) -X(-) binding. The heavier halogen atoms also bind covalently with the Ln-5d shell. Scalar relativistic effects contract and destabilize the LuX bonds, spin orbit coupling hardly affects the geometries but the bond energies, owing to SO effects in the free atoms. The relativistic changes of bond energy BE, bond length Re , bond force k, and bond stretching frequency vs do not follow the simple rules of Badger and Gordy (Re ∼BE∼k∼vs ). The so-called degeneracy-driven covalence, meaning strong mixing of accidentally near-degenerate, nearly nonoverlapping AOs without BE contribution is critically discussed. © 2015 Wiley Periodicals, Inc.
Photon-Induced Spin-Orbit Coupling in Ultracold Atoms inside Optical Cavity
Directory of Open Access Journals (Sweden)
Lin Dong
2015-05-01
Full Text Available We consider an atom inside a ring cavity, where a plane-wave cavity field together with an external coherent laser beam induces a two-photon Raman transition between two hyperfine ground states of the atom. This cavity-assisted Raman transition induces effective coupling between atom’s internal degrees of freedom and its center-of-mass motion. In the meantime, atomic dynamics exerts a back-action to cavity photons. We investigate the properties of this system by adopting a mean-field and a full quantum approach, and show that the interplay between the atomic dynamics and the cavity field gives rise to intriguing nonlinear phenomena.
Liu, Chao-Fei; JuzeliÅ«nas, Gediminas; Liu, W. M.
2017-02-01
Atomic-molecular Bose-Einstein condensates (BECs) offer brand new opportunities to revolutionize quantum gases and probe the variation of fundamental constants with unprecedented sensitivity. The recent realization of spin-orbit coupling (SOC) in BECs provides a new platform for exploring completely new phenomena unrealizable elsewhere. In this study, we find a way of creating a Rashba-Dresselhaus SOC in atomic-molecular BECs by combining the spin-dependent photoassociation and Raman coupling, which can control the formation and distribution of a different type of topological excitation—carbon-dioxide-like skyrmion. This skyrmion is formed by two half-skyrmions of molecular BECs coupling with one skyrmion of atomic BECs, where the two half-skyrmions locate at both sides of one skyrmion. Carbon-dioxide-like skyrmion can be detected by measuring the vortices structures using the time-of-flight absorption imaging technique in real experiments. Furthermore, we find that SOC can effectively change the occurrence of the Chern number in k space, which causes the creation of topological spin textures from some separated carbon-dioxide-like monomers each with topological charge -2 to a polymer chain of the skyrmions. This work helps in creating dual SOC atomic-molecular BECs and opens avenues to manipulate topological excitations.
Hu, Yanhui; Liu, Xuejing; Li, Yang; Yao, Han; Dai, Lingling; Yang, Biyao; Ding, Ming
2017-07-01
We present an ultrahigh-sensitivity electro-optic modulator (EOM) detection method for detecting the atomic Larmor precession in an all-optical K-Rb hybrid atomic magnetometer operating in the spin-exchange relaxation-free regime. A magnetic field sensitivity of ~10 f T Hz-1/2 has been achieved by optimizing the probe laser parameters and the EOM modulation conditions, which is comparable to that with the Faraday modulation method and has a better performance than the balanced polarimetry method in the low frequency range. The EOM detection method in the atomic magnetometer presents several advantages, such as simple structure, no extra magnetic noise, moderate thermal effect, high measurement sensitivity and reliable stability. It is demonstrated to be feasible for the improved compactness and simplicity of atomic magnetic field measurement devices in the future.
Bast, Radovan; Thorvaldsen, Andreas J.; Ringholm, Magnus; Ruud, Kenneth
2009-02-01
We present the first analytic calculations of the second hyperpolarizability in a relativistic framework. The calculations are made possible by our recent developments of a response theory built on a quasienergy formalism, in which the basis set may be both time and perturbation dependent. The approach is formulated for an arbitrary self-consistent field state in the atomic orbital basis. The implementation consists of a stand-alone code that only requires the unperturbed density in the atomic orbital basis as input, as well as a linear response solver by which we can determine the perturbed density matrices to different orders, at each new order solving equations that have the same structure as the linear response equation. Using these features of our formalism, we extend in this paper our approach to the relativistic domain, utilizing both two- and four-component relativistic wave functions. We apply the formalism to the calculation of the electronic and pure vibrational contributions to the second hyperpolarizability tensor for the hydrogen halides. Our results demonstrate that relativistic effects can be substantial for frequency-dependent second hyperpolarizabilities. Due to changes in the pole structure when going to the relativistic domain, the relativistic corrections to the hyperpolarizabilities are not transferable between different optical processes, except for very low frequencies.
Energy Technology Data Exchange (ETDEWEB)
Bast, Radovan; Thorvaldsen, Andreas J.; Ringholm, Magnus [Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromso, N-9037 Tromso (Norway); Ruud, Kenneth [Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromso, N-9037 Tromso (Norway)], E-mail: kenneth.ruud@chem.uit.no
2009-02-17
We present the first analytic calculations of the second hyperpolarizability in a relativistic framework. The calculations are made possible by our recent developments of a response theory built on a quasienergy formalism, in which the basis set may be both time and perturbation dependent. The approach is formulated for an arbitrary self-consistent field state in the atomic orbital basis. The implementation consists of a stand-alone code that only requires the unperturbed density in the atomic orbital basis as input, as well as a linear response solver by which we can determine the perturbed density matrices to different orders, at each new order solving equations that have the same structure as the linear response equation. Using these features of our formalism, we extend in this paper our approach to the relativistic domain, utilizing both two- and four-component relativistic wave functions. We apply the formalism to the calculation of the electronic and pure vibrational contributions to the second hyperpolarizability tensor for the hydrogen halides. Our results demonstrate that relativistic effects can be substantial for frequency-dependent second hyperpolarizabilities. Due to changes in the pole structure when going to the relativistic domain, the relativistic corrections to the hyperpolarizabilities are not transferable between different optical processes, except for very low frequencies.
Skachkov, Dmitry; Krykunov, Mykhaylo; Kadantsev, Eugene; Ziegler, Tom
2010-05-11
We present here a method that can calculate NMR shielding tensors from first principles for systems with translational invariance. Our approach is based on Kohn-Sham density functional theory and gauge-including atomic orbitals. Our scheme determines the shielding tensor as the second derivative of the total electronic energy with respect to an external magnetic field and a nuclear magnetic moment. The induced current density due to a periodic perturbation from nuclear magnetic moments is obtained through numerical differentiation, whereas the influence of the responding perturbation in terms of the external magnetic field is evaluated analytically. The method is implemented into the periodic program BAND. It employs a Bloch basis set made up of Slater-type or numeric atomic orbitals and represents the Kohn-Sham potential fully without the use of effective core potentials. Results from calculations of NMR shielding constants based on the present approach are presented for isolated molecules as well as systems with one-, two- and three-dimensional periodicity. The reported values are compared to experiment and results from calculations on cluster models.
Helmich-Paris, Benjamin; Repisky, Michal; Visscher, Lucas
2016-07-07
We present a formulation of Laplace-transformed atomic orbital-based second-order Møller-Plesset perturbation theory (MP2) energies for two-component Hamiltonians in the Kramers-restricted formalism. This low-order scaling technique can be used to enable correlated relativistic calculations for large molecular systems. We show that the working equations to compute the relativistic MP2 energy differ by merely a change of algebra (quaternion instead of real) from their non-relativistic counterparts. With a proof-of-principle implementation we study the effect of the nuclear charge on the magnitude of half-transformed integrals and show that for light elements spin-free and spin-orbit MP2 energies are almost identical. Furthermore, we investigate the effect of separation of charge distributions on the Coulomb and exchange energy contributions, which show the same long-range decay with the inter-electronic/atomic distance as for non-relativistic MP2. A linearly scaling implementation is possible if the proper distance behavior is introduced to the quaternion Schwarz-type estimates as for non-relativistic MP2.
Helmich-Paris, Benjamin; Visscher, Lucas
2016-01-01
We present a formulation of Laplace-transformed atomic orbital-based second-order M{\\o}ller-Plesset perturbation theory (MP2) energies for two-component Hamiltonians in the Kramers-restricted formalism. This low-order scaling technique can be used to enable correlated relativistic calculations for large molecular systems. We show that the working equations to compute the relativistic MP2 energy differ by merely a change of algebra (quaternion instead of real) from their non-relativistic counterparts. With a proof-of-principle implementation we study the effect of the nuclear charge on the magnitude of half-transformed integrals and show that for light elements spin-free and spin-orbit MP2 energies are almost identical. Furthermore, we investigate the effect of separation of charge distributions on the Coulomb and exchange energy con- tributions, which show the same long-range decay with the inter-electronic / atomic distance as for non-relativistic MP2. A linearly scaling implementation is possible if the pro...
Téllez Soto, C. A.; Costa, A. C.; Versiane, O.; Lemma, T.; Machado, N. C. F.; Mondragón, M. A.; Martin, A. A.
2015-07-01
Theoretical and experimental bands have been assigned to the Fourier Transform Infrared (FT-IR) and FT-Raman spectra of the bis(diethyldithiocarbamate)Cd(II) complex, abbreviated as ([Cd(DDTC)2]). The calculations and spectral interpretation have been based on the DFT/B3LYP method, infrared and Raman second derivative spectra, and band deconvolution analysis to assist in the assignment of observed fundamentals. This study validated the unusual pseudo tetrahedral molecular structure formed around the Cd(II) cation. Surface-enhanced Raman scattering (SERS) was used to determine the interactions of the normal-modes of the diethyldithiocarbamate cadmium (II) complex on nano-structured silver surfaces. Natural bond orbital (NBO) analysis was also carried out to study the Cd(II) hybridization causing the pseudo tetrahedral geometry of the framework of the [Cd(DDTC)2] complex, and to confirm the charge transfer mechanisms through second order perturbation theory analysis of the Fox Matrix. In order to find out the electronic dispersion of the Mulliken atomic charges (MAC) in the normal modes, we calculated the MAC for each normal mode and correlated these values with the SERS effect. Experimental UV-Vis spectra were obtained and charge transfer bands were assigned. Good agreement between the calculated and experimental values for the vibrational and UV-Vis spectra was obtained.
Ragot, Sébastien
2008-04-01
The ground-state Hartree-Fock (HF) wavefunction of Hooke's atom is not known in closed form, contrary to the exact solution. The single HF orbital involved has thus far been studied using expansion techniques only, leading to slightly disparate energies. Therefore, the present letter aims at proposing alternative definitions of the HF wavefunction. First, the HF limit is ascertained using a simple expansion, which makes it possible to formulate explicit expressions of HF properties. The resulting energy, 2.038 438 871 8 Eh, is found stable at the tenth digit. Second and more instructive, an analysis of the Hartree equation makes it possible to infer a remarkably simple and accurate HF orbital, i.e., φHF(r)=nHFe-αr2√r2+β2, leading to an energy exceeding by 5.76×10-7 Eh only the above HF limit. This orbital makes it possible to obtain (near) Hartree-Fock properties in closed form, which in turn enables handy comparisons with exact quantities.
Kordbacheh, A.; Ghahremaninezhad, Roghayeh; Maraghechi, B.
2012-09-01
A three-dimensional analysis of a novel free-electron laser (FEL) based upon a rectangular hybrid wiggler (RHW) is presented. This RHW is designed in a configuration composed of rectangular rings with alternating ferrite and dielectric spacers immersed in a solenoidal magnetic field. An analytic model of RHW is introduced by solution of Laplace's equation for the magnetostatic fields under the appropriate boundary conditions. The single-electron orbits in combined RHW and axial guide magnetic fields are studied when only the first and the third spatial harmonic components of the RHW field are taken into account and the higher order terms are ignored. The results indicate that the third spatial harmonic leads to group III orbits with a strong negative mass regime particularly in large solenoidal magnetic fields. RHW is found to be a promising candidate with favorable characteristics to be used in microwave FEL.
Photoionization of neutral atoms by X waves carrying orbital angular momentum
Müller, Robert A.; Seipt, Daniel; Beerwerth, Randolf; Ornigotti, Marco; Szameit, Alexander; Fritzsche, Stephan; Surzhykov, Andrey
2016-10-01
In contrast to plane waves, twisted or vortex beams have a complex spatial structure. Both their intensity and energy flow vary within the wave front. Beyond that, polychromatic vortex beams, such as X waves, have a spatially dependent energy distribution. We propose a method to measure this (local) energy spectrum. The method is based on the measurement of the energy distribution of photoelectrons from alkali-metal atoms. On the basis of our fully relativistic calculations, we argue that even ensembles of atoms can be used to probe the local energy spectrum of short twisted pulses.
All-atom/coarse-grained hybrid predictions of distribution coefficients in SAMPL5
Genheden, Samuel; Essex, Jonathan W.
2016-11-01
We present blind predictions submitted to the SAMPL5 challenge on calculating distribution coefficients. The predictions were based on estimating the solvation free energies in water and cyclohexane of the 53 compounds in the challenge. These free energies were computed using alchemical free energy simulations based on a hybrid all-atom/coarse-grained model. The compounds were treated with the general Amber force field, whereas the solvent molecules were treated with the Elba coarse-grained model. Considering the simplicity of the solvent model and that we approximate the distribution coefficient with the partition coefficient of the neutral species, the predictions are of good accuracy. The correlation coefficient, R is 0.64, 82 % of the predictions have the correct sign and the mean absolute deviation is 1.8 log units. This is on a par with or better than the other simulation-based predictions in the challenge. We present an analysis of the deviations to experiments and compare the predictions to another submission that used all-atom solvent.
Institute of Scientific and Technical Information of China (English)
刘洪毓
2007-01-01
Atoms(原子)are all around us.They are something like the bricks (砖块)of which everything is made. The size of an atom is very,very small.In just one grain of salt are held millions of atoms. Atoms are very important.The way one object acts depends on what
Institute of Scientific and Technical Information of China (English)
Xiong Zhuang; Bacalis N C
2006-01-01
An analytic configuration interaction method based on variationally optimized internally orthogonalized modified Laguerre orbitals is presented. We have developed the corresponding computer code. For application, we study the ls2s 1S isoelectronic sequence from helium to neon, and compare with other methods. By taking into account the Eckart upper-bound theorem, we obtained more accurate and more intuitively understandable results than Hartree-Fock and multi-configuration Hartree-Fock reported results.
Institute of Scientific and Technical Information of China (English)
Longfei Hu; Meishuan Li; Yanchun Zhou
2009-01-01
Polysiloxane/SiO2 hybrid coatings have been prepared on Kapton films by a sol-gel process. The erosion resistance of polysiloxane/SiO2 (20 wt pct) coating was evaluated by exposure tests of vacuum ultraviolet radiation (VUV) and atomic oxygen beam (AO) in a ground-based simulation facility. The experimental results indicate that this coating exhibits better AO resistance than pure polysiloxane coating. The erosion yield (Ey) of the polysiloxane/SiO2 (20 wt pct) hybrid coating is about 10-27 cm3/atom, being one or two orders of magnitude lower than that of polysiloxane. VUV radiation can affect the erosion process greatly. Under simultaneous AO and VUV exposure, the value of Ey of the polysiloxane/SiO2 (20 wt pct) hybrid coating increases by 39% compared with that under single AO exposure.
DEFF Research Database (Denmark)
Avery, John Scales; Avery, James Emil; Aquilanti, Vincenzo;
2004-01-01
The generalized Sturmian method for atomic and molecular electronic structure calculations is a direct configuration interaction method in which the configurations are chosen to be isoenergetic solutions of an approximate N-electron Schrödinger equation with a weighted potential, $\\beta_\
National Aeronautics and Space Administration — Goals:1. Continue development of a flexible facility capable of small scale hybrid propulsion tests. The facility will be able to adapt to new research objectives as...
Ito, Yosuke; Sato, Daichi; Kamada, Keigo; Kobayashi, Tetsuo
2016-07-11
An optically pumped K-Rb hybrid atomic magnetometer can be a useful tool for biomagnetic measurements due to the high spatial homogeneity of its sensor property inside a cell. However, because the property varies depending on the densities of potassium and rubidium atoms, optimization of the densities is essential. In this study, by using the Bloch equations of K and Rb and considering the spatial distribution of the spin polarization, we confirmed that the calculation results of spin polarization behavior are in good agreement with the experimental data. Using our model, we calculated the spatial distribution of the spin polarization and found that the optimal density of K atoms is 3 × 1019 m-3 and the optimal density ratio is nK/nRb ~ 400 to maximize the output signal and enhance spatial homogeneity of the sensor property.
Energy Technology Data Exchange (ETDEWEB)
Wright, Joshua T.; Forsythe, Kyle; Hutchins, Jamie; Meulenberg, Robert W.
2016-04-13
This paper investigates how chemical dopants affect the electronic properties of CdSe quantum dots (QDs) and why a model that incorporates the concepts of orbital hybridization must be used to understand these properties. Extended X-ray absorption fine structure spectroscopy measurements show that copper dopants in CdSe QDs occur primarily through a statistical doping mechanism. Ultraviolet photoemission spectroscopy (UPS) experiments provide a detailed insight on the valence band (VB) structure of doped and undoped QDs. Using UPS measurements, we are able to observe photoemission from the Cu d-levels above VB maximum of the QDs which allows a complete picture of the energy band landscape of these materials. This information provides insights into many of the physical properties of doped QDs, including the highly debated near-infrared photoluminescence in Cu doped CdSe QDs. We show that all our results point to a common theme of orbital hybridization in Cu doped CdSe QDs which leads to optically and electronically active states below the conduction band minimum. Our model is supported from current–voltage measurements of doped and undoped materials, which exhibit Schottky to Ohmic behavior with Cu doping, suggestive of a tuning of the lowest energy states near the Fermi level.
The Role of Super-Atom Molecular Orbitals in Doped Fullerenes in a Femtosecond Intense Laser Field.
Xiong, Hui; Mignolet, Benoit; Fang, Li; Osipov, Timur; Wolf, Thomas J A; Sistrunk, Emily; Gühr, Markus; Remacle, Francoise; Berrah, Nora
2017-12-01
The interaction of gas phase endohedral fullerene Ho3N@C80 with intense (0.1-5 × 10(14) W/cm(2)), short (30 fs), 800 nm laser pulses was investigated. The power law dependence of Ho3N@C80(q+), q = 1-2, was found to be different from that of C60. Time-dependent density functional theory computations revealed different light-induced ionization mechanisms. Unlike in C60, in doped fullerenes, the breaking of the cage spherical symmetry makes super atomic molecular orbital (SAMO) states optically active. Theoretical calculations suggest that the fast ionization of the SAMO states in Ho3N@C80 is responsible for the n = 3 power law for singly charged parent molecules at intensities lower than 1.2 × 10(14) W/cm(2).
Lehtola, Susi; Jónsson, Elvar Ö; Jónsson, Hannes
2016-09-13
The spurious interaction of an electron with itself-self-interaction error-is one of the biggest problems in modern density-functional theory. Some of its most glaring effects, such as qualitatively incorrect charge separation upon dissociation, can be removed by an approximate self-interaction correction due to Perdew and Zunger (PZ) (Perdew, J.; Zunger, A. Phys. Rev. B 1981, 23, 5048). However, the correction introduces an explicit dependence on the occupied orbital densities, which makes proper minimization of the functional difficult. Previous work (Vydrov et al., J. Chem. Phys. 2006, 124, 094108) has suggested that the application of the PZ correction results in worse atomization energies than those obtained with the uncorrected parent functional. But, it has only recently been found that the correct minimization of the PZ energy functional requires complex-valued orbitals, which have not been used in previous work on atomization energies. Here, we study the effect of the proper use of complex-valued orbitals on the atomization energies of molecules in the W4-11 data set (Karton, A.; Daon, S.; Martin, J. M. Chem. Phys. Lett. 2001, 510, 165). We find that the correction has a tendency to weaken the binding of molecules. The correction using complex-valued orbitals is invariably found to yield better atomization energies than the correction with real-valued orbitals. The correction applied to the PBEsol exchange-correlation functional results in a functional that is more accurate than the (uncorrected) PBE functional.
Controlling Atomic, Solid-State and Hybrid Systems for Quantum Information Processing
Gullans, Michael John
Quantum information science involves the use of precise control over quantum systems to explore new technologies. However, as quantum systems are scaled up they require an ever deeper understanding of many-body physics to achieve the required degree of control. Current experiments are entering a regime which requires active control of a mesoscopic number of coupled quantum systems or quantum bits (qubits). This thesis describes several approaches to this goal and shows how mesoscopic quantum systems can be controlled and utilized for quantum information tasks. The first system we consider is the nuclear spin environment of GaAs double quantum dots containing two electrons. We show that the through appropriate control of dynamic nuclear polarization one can prepare the nuclear spin environment in three distinct collective quantum states which are useful for quantum information processing with electron spin qubits. We then investigate a hybrid system in which an optical lattice is formed in the near field scattering off an array of metallic nanoparticles by utilizing the plasmonic resonance of the nanoparticles. We show that such a system would realize new regimes of dense, ultra-cold quantum matter and can be used to create a quantum network of atoms and plasmons. Finally we investigate quantum nonlinear optical systems. We show that the intrinsic nonlinearity for plasmons in graphene can be large enough to make a quantum gate for single photons. We also consider two nonlinear optical systems based on ultracold gases of atoms. In one case, we demonstrate an all-optical single photon switch using cavity quantum electrodynamics (QED) and slow light. In the second case, we study few photon physics in strongly interacting Rydberg polariton systems, where we demonstrate the existence of two and three photon bound states and study their properties.
Institute of Scientific and Technical Information of China (English)
Shubao Wang; Xueyou Xu; Hongyun Li; Zhengmao Jia; Shenglu Lin
2008-01-01
The formulas of the quantum electrodynamics have been applied to calculate the spontaneous emission rate of excited atom in dielectric microcavity.The results exhibit damping oscillating Patterns which depend sensitively on the scaling parameter and geometrical structure.Compared with the case that the emitting atom is immersed in dielectric,the spontaneous emission rate is depressed obviously and the center or the mean value of the oscillations is intimately related to the real refractive index of the local position where the atom is.In order to explain this phenomenon,we utilize the closed-orbit theory to deal with the classical trajectories of the emitted photon.and extract the corresponding frequencies of the oscillations by Fourier transform.It is found that the oscillations can be represented in terms of the closed-orbits of the photon motion constrained in dielectric microcavity,thus providing another perspective on the spontaneous emission of atom sandwiched by dielectric slabs.
Even-odd spatial nonequivalence for atomic quantum gases with isotropic spin-orbit couplings
Singh, G. S.; Gupta, Reena
2014-05-01
A general expression for the density of states (DOS) of power-law trapped d-dimensional ideal quantum gases with isotropic spin-orbit couplings (SOCs) is derived and is found to bifurcate into even- dand odd- d classes. The expressions for the grand potential and hence for several thermodynamic quantities are then shown to be amenable to exact analytical forms provided d is an odd integer. Also, a condition γ transition temperature and the condensate fraction in a 3D Bose gas under combined presence of the harmonic trapping and the Weyl coupling shows that the condensation is favored by the former but disfavored by the latter. This countering behavior is discussed to be in conformity with the exchange-symmetry-induced statistical interactions resulting from these two entities as enunciated recently [Phys. Rev. A 88, 053607 (2013)].
Devarajan, Deepa; Gustafson, Samantha J.; Bickelhaupt, F. Matthias; Ess, Daniel H.
2015-01-01
Undergraduate organic chemistry textbooks and Internet websites use a variety of approaches for presenting and explaining the impact of halogen atom size on trends in bond strengths and/or acidity of hydrogen halides. In particular, several textbooks and Internet websites explain these trends by invoking decreasing orbital overlap between the…
Lesiuk, Michał
2014-01-01
In this paper, which constitutes the first part of the series, we consider calculation of two-centre Coulomb and hybrid integrals over Slater-type orbitals (STOs). General formulae for these integrals are derived with no restrictions on the values of the quantum numbers and nonlinear parameters. Direct integration over the coordinates of one of the electrons leaves us with the set of overlap-like integrals which are evaluated by using two distinct methods. The first one is based on the transformation to the ellipsoidal coordinates system and the second utilises a recursive scheme for consecutive increase of the angular momenta in the integrand. In both methods simple one-dimensional numerical integrations are used in order to avoid severe digital erosion connected with the straightforward use of the alternative analytical formulae. It is discussed that the numerical integration does not introduce a large computational overhead since the integrands are well-behaved functions, calculated recursively with decent...
Moshonov, Moshe; Frey, Gitti L
2015-11-24
The simplicity and versatility of block copolymer self-assembly offers their use as templates for nano- and meso-structured materials. However, in most cases, the material processing requires multiple steps, and the block copolymer is a sacrificial building block. Here, we combine a self-assembled block copolymer template and atomic layer deposition (ALD) of a metal oxide to generate functional hybrid films in a simple process with no etching or burning steps. This approach is demonstrated by using the crystallization-induced self-assembly of a rod-coil block copolymer, P3HT-b-PEO, and the ALD of ZnO. The block copolymer self-assembles into fibrils, ∼ 20 nm in diameter and microns long, with crystalline P3HT cores and amorphous PEO corona. The affinity of the ALD precursors to the PEO corona directs the exclusive deposition of crystalline ZnO within the PEO domains. The obtained hybrid structure possesses the properties desired for photovoltaic films: donor-acceptor continuous nanoscale interpenetrated networks. Therefore, we integrated the films into single-layer hybrid photovoltaics devices, thus demonstrating that combining self-assembly of functional block copolymers and ALD is a simple approach to direct desired complex hybrid morphologies.
Espinosa-Garciá, Joaquín; Rangel, Cipriano; Navarrete, Marta; Corchado, José C
2004-09-15
A computational approach to calculating potential energy surfaces for reactive systems is presented and tested. This hybrid approach is based on integrated methods where calculations for a small model system are performed by using analytical potential energy surfaces, and for the real system by using molecular orbital or molecular mechanics methods. The method is tested on a hydrogen abstraction reaction by using the variational transition-state theory with multidimensional tunneling corrections. The agreement between the calculated and experimental information depends on the quality of the method chosen for the real system. When the real system is treated by accurate quantum mechanics methods, the rate constants are in excellent agreement with the experimental measurements over a wide temperature range. When the real system is treated by molecular mechanics methods, the results are still good, which is very encouraging since molecular mechanics itself is not at all capable of describing this reactive system. Since no experimental information or additional fits are required to apply this method, it can be used to improve the accuracy of molecular orbital methods or to extend the molecular mechanics method to treat any reactive system with the single constraint of the availability of an analytical potential energy surface that describes the model system.
Hybrid RHF/MP2 geometry optimizations with the effective fragment molecular orbital method
DEFF Research Database (Denmark)
Christensen, Anders Steen; Svendsen, Casper Steinmann; Fedorov, Dmitri G
2014-01-01
The frozen domain effective fragment molecular orbital method is extended to allow for the treatment of a single fragment at the MP2 level of theory. The approach is applied to the conversion of chorismate to prephenate by Chorismate Mutase, where the substrate is treated at the MP2 level of theory...... while the rest of the system is treated at the RHF level. MP2 geometry optimization is found to lower the barrier by up to 3.5 kcal/mol compared to RHF optimzations and ONIOM energy refinement and leads to a smoother convergence with respect to the basis set for the reaction profile. For double zeta...
850-nm hybrid fiber/free-space optical communications using orbital angular momentum modes
DEFF Research Database (Denmark)
Jurado-Navas, Antonio; Tatarczak, Anna; Lu, Xiaofeng;
2015-01-01
Light beams can carry orbital angular momentum (OAM) associated to the helicity of their phasefronts. These OAM modes can be employed to encode information onto a laser beam for transmitting not only in a fiber link but also in a free-space optical (FSO) one. Regarding this latter scenario, FSO...... modes can be seen as an efficient solution to increase the capacity and the security in the link. In this paper, we discuss an experimental demonstration of a proposal for next generation FSO communication system where a light beam carrying different OAM modes and affected by M turbulence is coupled...
Orbital Hybridization of the Ferroelectric Rb2Cd2 (SO4)3: Origin of Domain Walls
Institute of Scientific and Technical Information of China (English)
DUAN Yi-Feng; YI Lin
2005-01-01
@@ We perform first-principle calculations for the study of the orthorhombic Rb2Cd2 (SO4)3 structure. Electronic energy bands, total and partial densities of states are reported and analysed. It is found that oxygen atomic 2p electrons strongly hybridize with Rb/or Cd 4d and S 2p states, resulting in two-type ionic groups with weak couplings. It is shown that macroscopic domain walls originate from such weak-coupling ionic groups, arising at the cell boundaries. The asymmetric cation bonds (Rb-O and Cd-O) and the subsequent rotations of the SO4tetrahedra can lead to the driving force of the ferroelectric behaviour. The predicted pyroelectric current effects are observed experimentally in the ferroelectric phase.
Goings, Joshua J; Li, Xiaosong
2016-06-21
One of the challenges of interpreting electronic circular dichroism (ECD) band spectra is that different states may have different rotatory strength signs, determined by their absolute configuration. If the states are closely spaced and opposite in sign, observed transitions may be washed out by nearby states, unlike absorption spectra where transitions are always positive additive. To accurately compute ECD bands, it is necessary to compute a large number of excited states, which may be prohibitively costly if one uses the linear-response time-dependent density functional theory (TDDFT) framework. Here we implement a real-time, atomic-orbital based TDDFT method for computing the entire ECD spectrum simultaneously. The method is advantageous for large systems with a high density of states. In contrast to previous implementations based on real-space grids, the method is variational, independent of nuclear orientation, and does not rely on pseudopotential approximations, making it suitable for computation of chiroptical properties well into the X-ray regime.
Indian Academy of Sciences (India)
Heidar Raissi; Mehdi Yoosefian; Effat Moshfeghi; Farzaneh Farzad
2012-05-01
The characteristics of the intramolecular hydrogen bonding for a series of 19 different derivatives of -aminoacroleine have been systematically analysed at the B3LYP/6-31G∗∗ level of theory. The topological properties of the electron density distributions for N-H$\\cdots$O intramolecular bridges have been analysed by the Bader theory of atoms in molecules. The electron density () and Laplacian (∇2 ρ) properties at critical points of the relevant bonds, estimated by AIM calculations, showed that N-H$\\cdots$O have low and positive character (∇2 ρ > 0), consistent with electrostatic character of the hydrogen bond. The vibrational study of the hydrogen bonded systems showed negative (red) shifts for the (N−H) stretching mode. The -electron delocalization parameter () as a geometrical indicator of a local aromaticity and the geometry-based HOMA have also been calculated. Furthermore, the analysis of hydrogen bond in this molecule and its derivatives by natural bond orbital (NBO) methods support the DFT results. The results of AIM and NBO analysis as well as (N−H) were further used for estimation of the hydrogen bonding interactions and the forces driving their formation. The various correlations were found between geometrical, energetic and topological parameters. The substituent effect was also analysed and it was found that the strongest hydrogen bonds exist for N+(CH3)3 and Cl substituents while the weakest ones for COOCH3.
Maschio, Lorenzo; Kirtman, Bernard; Rérat, Michel; Orlando, Roberto; Dovesi, Roberto
2013-10-28
We present a fully analytical formulation for calculating Raman intensities of crystalline periodic systems using a local basis set. Numerical differentiation with respect to atomic coordinates and with respect to wavevectors is entirely avoided as is the determination of crystal orbital coefficient derivatives with respect to nuclear displacements. Instead, our method utilizes the orbital energy-weighted density matrix and is based on the self-consistent solution of first- and second-order Coupled Perturbed Hartree-Fock/Kohn-Sham equations for the electronic response to external electric fields at the equilibrium geometry. This method has also been implemented in the Crystal program, which uses a Gaussian type basis set.
Energy Technology Data Exchange (ETDEWEB)
Charlier, J-C; Zanolli, Z [Unite de Physico-Chimie et de Physique des Materiaux (PCPM), European Theoretical Spectroscopy Facility (ETSF), Universite Catholique de Louvain, Place Croix du Sud 1, B-1348 Louvain-la-Neuve (Belgium); Arnaud, L; Avilov, I V; Felten, A; Pireaux, J-J [Centre de Recherche en Physique de la Matiere et du Rayonnement (PMR-LISE), Facultes Universitaires Notre-Dame de la Paix, 61 Rue de Bruxelles, B-5000 Namur (Belgium); Delgado, M [Sensotran, s.l., Avenida Remolar 31, E-08820 El Prat de Llobregat, Barcelona (Spain); Demoisson, F; Reniers, F [Service de Chimie Analytique et Chimie des Interfaces (CHANI), Universite Libre de Bruxelles, Faculte des Sciences, CP255, Boulevard du Triomphe 2, B-1050 Bruxelles (Belgium); Espinosa, E H; Ionescu, R; Leghrib, R; Llobet, E [Department of Electronic Engineering, Universitat Rovira i Virgili, Avenida Paisos Catalans 26, E-43007 Tarragona (Spain); Ewels, C P; Suarez-Martinez, I [Institut des Materiaux Jean Rouxel (IMN), Universite de Nantes, 2 rue de la Houssiniere-BP 32229, F-44322 Nantes Cedex 3 (France); Guillot, J; Mansour, A; Migeon, H-N [Departement Science et Analyse des Materiaux, Centre de Recherche Public-Gabriel Lippmann, rue du Brill 41, L-4422 Belvaux (Luxembourg); Watson, G E, E-mail: jean-jacques.pireaux@fundp.ac.b [Vega Science Trust, Unit 118, Science Park SQ, Brighton, BN1 9SB (United Kingdom)
2009-09-16
Carbon nanotube surfaces, activated and randomly decorated with metal nanoclusters, have been studied in uniquely combined theoretical and experimental approaches as prototypes for molecular recognition. The key concept is to shape metallic clusters that donate or accept a fractional charge upon adsorption of a target molecule, and modify the electron transport in the nanotube. The present work focuses on a simple system, carbon nanotubes with gold clusters. The nature of the gold-nanotube interaction is studied using first-principles techniques. The numerical simulations predict the binding and diffusion energies of gold atoms at the tube surface, including realistic atomic models for defects potentially present at the nanotube surface. The atomic structure of the gold nanoclusters and their effect on the intrinsic electronic quantum transport properties of the nanotube are also predicted. Experimentally, multi-wall CNTs are decorated with gold clusters using (1) vacuum evaporation, after activation with an RF oxygen plasma and (2) colloid solution injected into an RF atmospheric plasma; the hybrid systems are accurately characterized using XPS and TEM techniques. The response of gas sensors based on these nano{sup 2}hybrids is quantified for the detection of toxic species like NO{sub 2}, CO, C{sub 2}H{sub 5}OH and C{sub 2}H{sub 4}.
Yang, Shi-Peng; Lu, Mao-Wang; Huang, Xin-Hong; Tang, Qiang; Zhou, Yong-Long
2017-04-01
A theoretical study has been carried out on the spin-dependent electron transport in a hybrid magnetic-electric barrier nanostructure with both Rashba and Dresselhaus spin-orbit couplings, which can be experimentally realized by depositing a ferromagnetic strip and a Schottky metal strip on top of a semiconductor heterostructure. The spin-orbit coupling-dependent transmission coefficient, conductance, and spin polarization are calculated by solving the Schrödinger equation exactly with the help of the transfer-matrix method. We find that both the magnitude and sign of the electron spin polarization vary strongly with the spin-orbit coupling strength. Thus, the degree of electron spin polarization can be manipulated by properly adjusting the spin-orbit coupling strength, and such a nanosystem can be employed as a controllable spin filter for spintronics applications.
850-nm hybrid fiber/free-space optical communications using orbital angular momentum modes.
Jurado-Navas, Antonio; Tatarczak, Anna; Lu, Xiaofeng; Olmos, Juan José Vegas; Garrido-Balsells, José María; Monroy, Idelfonso Tafur
2015-12-28
Light beams can carry orbital angular momentum (OAM) associated to the helicity of their phasefronts. These OAM modes can be employed to encode information onto a laser beam for transmitting not only in a fiber link but also in a free-space optical (FSO) one. Regarding this latter scenario, FSO communications are considered as an alternative and promising mean complementing the traditional optical communications in many applications where the use of fiber cable is not justified. This next generation FSO communication systems have attracted much interest recently, and the inclusion of beams carrying OAM modes can be seen as an efficient solution to increase the capacity and the security in the link. In this paper, we discuss an experimental demonstration of a proposal for next generation FSO communication system where a light beam carrying different OAM modes and affected by ℳ turbulence is coupled to the multimode fiber link. In addition, we report a better and more robust behavior of higher order OAM modes when the intermodal dispersion is dominant in the fiber after exceeding its maximum range of operation.
DEFF Research Database (Denmark)
Kjærgaard, Thomas; Jørgensen, Poul; Thorvaldsen, Andreas;
2009-01-01
-orbital density-matrix based formulation of response theory and use London atomic orbitals to parametrize the magnetic field dependence. It yields a computational procedure which is both gauge-origin independent and suitable for linear-scaling at the level of time-dependent Hartree-Fock and density functional......A Lagrangian approach has been used to derive gauge-origin independent expressions for two properties that rationalize magneto-optical activity, namely the Verdet constant V(ω) of the Faraday effect and the B term of magnetic circular dichroism. The approach is expressed in terms of an atomic...... theory. The formulation includes a modified preconditioned conjugated gradient algorithm, which projects out the excited state component from the solution to the linear response equation. This is required when solving one of the response equations for the determination of the B term and divergence...
Zhong, Hai; Schwarz, Alexander; Wiesendanger, Roland; Christoph, Philipp; Wagner, Tobias; Bick, Andreas; Staarmann, Christina; Abeln, Benjamin; Sengstock, Klaus; Becker, Christoph
2016-01-01
We describe the construction of an apparatus designed to realize a hybrid quantum system comprised of a cryogenically cooled mechanical oscillator and ultra-cold $^{87}$Rb atoms coupled via light. The outstanding feature of our instrument is an in-situ adjustable asymmetric all-fiber membrane-in-the-middle cavity located inside an ultra-high vacuum dilution refrigerator based cryostat. We show that Bose-Einstein condensates of $N=2\\times10^6$ atoms can be produced in less than 20 s and demonstrate a single photon optomechanical coupling strength of $g_0=2\\pi\\times9$ kHz employing a high-stress Si$_3$N$_4$ membrane with a mechanical quality factor $Q_{\\rm m}>10^7$ at a cavity set-up temperature of $T_{\\rm MiM}=480$ mK.
Observation of a power-law energy distribution in atom-ion hybrid system
Meir, Ziv; Akerman, Nitzan; Sikorsky, Tomas; Ben-Shlomi, Ruti; Dallal, Yehonatan; Ozeri, Roee
2016-05-01
Understanding atom-ion collision dynamics is at the heart of the growing field of ultra-cold atom-ion physics. The naive picture of a hot ion sympathetically-cooled by a cold atomic bath doesn't hold due to the time dependent potentials generated by the ion Paul trap. The energy scale of the atom-ion system is determined by a combination of the atomic bath temperature, the ion's excess micromotion (EMM) and the back action of the atom-ion attraction on the ion's position in the trap. However, it is the position dependent ion's inherent micromotion which acts as an amplifier for the ion's energy during random consecutive collisions. Due to this reason, the ion's energy distribution deviates from Maxwell-Boltzmann (MB) characterized by an exponential tail to one with power-law tail described by Tsallis q-exponential function. Here we report on the observation of a strong deviation from MB to Tsallis energy distribution of a trapped ion. In our experiment, a ground-state cooled 88 Sr+ ion is immersed in an ultra-cold cloud of 87 Rb atoms. The energy scale is determined by either EMM or solely due to the back action on the ion position during a collision with an atom in the trap. Energy distributions are obtained using narrow optical clock spectroscopy.
Guan, Binbin; Scott, Ryan P; Qin, Chuan; Fontaine, Nicolas K; Su, Tiehui; Ferrari, Carlo; Cappuzzo, Mark; Klemens, Fred; Keller, Bob; Earnshaw, Mark; Yoo, S J B
2014-01-13
We demonstrate free-space space-division-multiplexing (SDM) with 15 orbital angular momentum (OAM) states using a three-dimensional (3D) photonic integrated circuit (PIC). The hybrid device consists of a silica planar lightwave circuit (PLC) coupled to a 3D waveguide circuit to multiplex/demultiplex OAM states. The low excess loss hybrid device is used in individual and two simultaneous OAM states multiplexing and demultiplexing link experiments with a 20 Gb/s, 1.67 b/s/Hz quadrature phase shift keyed (QPSK) signal, which shows error-free performance for 379,960 tested bits for all OAM states.
Le Lay, Guy; de Padova, Paola; Quaresima, Claudio; Olivieri, Bruno; Perfetti, Paolo
2011-03-01
We have synthesized for the first time silicene, that is, a new silicon allotrope analogous to graphene recently theoretically predicted, in the form of a massively parallel array of quantized zigzag nano-ribbons with a common ``magic'' width of 1.6 nm. They display characteristic linear band dispersions similar to the Dirac cones of graphene, in correspondence with their hexagonal arrangement seen in STM imaging. Here we show, through the angle-dependence of REEL spectra taken at the Si L2 , 3 edge, the typical signatures of 2p --> π * and 2p --> σ * transitions associated with sp 2 hybridization of the Si valence orbitals. We further show through high-resolution synchrotron radiation Si 2p core-level spectroscopy measurements that the afore mentioned silicene grating is very resistant toward oxidation. Typically, the oxygen uptake starts at about 104 higher doses than on the clean Si(111)7x7 surface. Indeed, this striking behavior is directly related to the sp 2 bonding, an additional confirmation of the silicene (i.e., graphene-like) nature of the nano-ribbons.
Hall, Felix H J; Hegi, Gregor; Raoult, Maurice; Aymar, Mireille; Dulieu, Olivier; Willitsch, Stefan
2013-01-01
Cold chemical reactions between laser-cooled Ca^+ ions and Rb atoms were studied in an ion-atom hybrid trap. Reaction rate constants were determined in the range of collision energies /k_B = 20 mK-20 K. The lowest energies were achieved in experiments using single localized Ca^+ ions. Product branching ratios were studied using resonant-excitation mass spectrometry. The dynamics of the reactive processes in this system (non-radiative and radiative charge transfer as well as radiative association leading to the formation of CaRb^+ molecular ions) have been analyzed using high-level quantum-chemical calculations of the potential energy curves of CaRb^+ and quantum-scattering calculations for the radiative channels. For the present low-energy scattering experiments, it is shown that the energy dependence of the reaction rate constants is governed by long-range interactions in line with the classical Langevin model, but their magnitude is determined by short-range non-adiabatic and radiative couplings which only ...
Tuning Casimir-Polder interactions in atom-metamaterial hybrid devices
Chan, Eng Aik; Adamo, Giorgio; Laliotis, Athanasios; Ducloy, Martial; Wilkowski, David
2016-01-01
We report on the coupling of a surface plasmonic mode with a thermal vapor of cesium atoms. The plasmonic resonance is created using a nano-structured metallic surface. By changing the geometrical properties of the metamaterial, we tune the plasmonic resonance wavelength with respect to the D2 line of cesium. When the two resonances are close, we observe a strong modification of the Casimir-Polder interaction accompanied by a change of the atomic lifetime. A proper tuning leads to an almost suppression of the frequency shift of the cesium transition. This result paves the way for precision atomic spectroscopy in the vicinity of a material surface.
Hybrid excitations due to crystal field, spin-orbit coupling, and spin waves in LiFePO4
Yiu, Yuen; Le, Manh Duc; Toft-Peterson, Rasmus; Ehlers, Georg; McQueeney, Robert J.; Vaknin, David
2017-03-01
We report on the spin waves and crystal field excitations in single crystal LiFePO4 by inelastic neutron scattering over a wide range of temperatures, below and above the antiferromagnetic transition of this system. In particular, we find extra excitations below TN=50 K that are nearly dispersionless and are most intense around magnetic zone centers. We show that these excitations correspond to transitions between thermally occupied excited states of Fe2 + due to splitting of the S =2 levels that arise from the crystal field and spin-orbit interactions. These excitations are further amplified by the highly distorted nature of the oxygen octahedron surrounding the iron atoms. Above TN, magnetic fluctuations are observed up to at least 720 K, with an additional inelastic excitation around 4 meV, which we attribute to single-ion effects, as its intensity weakens slightly at 720 K compared to 100 K, which is consistent with the calculated cross sections using a single-ion model. Our theoretical analysis, using the MF-RPA model, provides both detailed spectra of the Fe d shell and estimates of the average ordered magnetic moment and TN. By applying the MF-RPA model to a number of existing spin-wave results from other Li M PO4 (M =Mn , Co, and Ni), we are able to obtain reasonable predictions for the moment sizes and transition temperatures.
Genheden, Samuel
2017-09-01
We present the estimation of solvation free energies of small solutes in water, n-octanol and hexane using molecular dynamics simulations with two MARTINI models at different resolutions, viz. the coarse-grained (CG) and the hybrid all-atom/coarse-grained (AA/CG) models. From these estimates, we also calculate the water/hexane and water/octanol partition coefficients. More than 150 small, organic molecules were selected from the Minnesota solvation database and parameterized in a semi-automatic fashion. Using either the CG or hybrid AA/CG models, we find considerable deviations between the estimated and experimental solvation free energies in all solvents with mean absolute deviations larger than 10 kJ/mol, although the correlation coefficient is between 0.55 and 0.75 and significant. There is also no difference between the results when using the non-polarizable and polarizable water model, although we identify some improvements when using the polarizable model with the AA/CG solutes. In contrast to the estimated solvation energies, the estimated partition coefficients are generally excellent with both the CG and hybrid AA/CG models, giving mean absolute deviations between 0.67 and 0.90 log units and correlation coefficients larger than 0.85. We analyze the error distribution further and suggest avenues for improvements.
Simple Link Atom Saccharide Hybrid (SLASH) Treatment for Glycosidic Bonds at the QM/MM Boundary.
Crous, Werner; Field, Martin J; Naidoo, Kevin J
2014-04-08
We investigated link atom approaches for treating the polar C-O bond with particular reference to the glycosidic bond found in complex carbohydrates. We show that cutting this bond after the oxygen in the QM region and saturating the QM system with a hydrogen link atom leads to greater conformational and configurational accuracy at the boundary compared with cutting the bond before oxygen and saturating the QM system with a halogen link atom to represent the oxygen. Furthermore, we find that balancing the MM atom charges and redistributing the boundary atom charges at the QM/MM boundary minimizes the effect of the link atom, both energetically and structurally. This is illustrated via a series of calculations on a set of carbohydrate and carbohydrate-like model compounds. Finally, we confirm the validity of our model by performing molecular dynamics simulations for a typical disaccharide model compound in water. Our postsimulation conformational and configurational analyses show that the oxygen-to-water hydrogen pair distribution functions and the Φ,Ψ distributions at the glycosidic boundary between the quantum and classical regions compare favorably with results obtained from complete QM and complete MM treatments of the saccharide.
Mizumaki, M; Saito, T; Shiraki, H; Shimakawa, Y
2009-04-20
X-ray absorption spectroscopy (XAS) spectra near the O K-edge of A-site-ordered perovskite with A-site Cu(2+) (S = (1)/(2)) spins were measured. The spectra of ferromagnetic CaCu(3)Ge(4)O(12) and CaCu(3)Sn(4)O(12) showed hybridization between Cu 3d and O 2p orbitals, but magnetic circular dichroism measurement revealed that the O 2p orbital played a less important role in magnetic interaction. The XAS spectra of antiferromagnetic CaCu(3)Ti(4)O(12), on the other hand, showed strong hybridization of the Cu 3d, Ti 3d, and O 2p orbitals. These results demonstrated that direct exchange interaction of the Cu(2+) spins primarily determined the ferromagnetic ordering of CaCu(3)Ge(4)O(12) and CaCu(3)Sn(4)O(12), whereas the involvement of Ti 3d orbitals induced the antiferromagnetic property in CaCu(3)Ti(4)O(12).
Energy Technology Data Exchange (ETDEWEB)
Belenkov, E. A., E-mail: belenkov@csu.ru [Chelyabinsk State University (Russian Federation); Mavrinskii, V. V. [Nosov Magnitogorsk State Technical University (Russian Federation); Belenkova, T. E.; Chernov, V. M. [Chelyabinsk State University (Russian Federation)
2015-05-15
A model scheme is proposed for obtaining layered compounds consisting of carbon atoms in the sp- and (vnsp){sup 2}-hybridized states. This model is used to find the possibility of existing the following seven basic structural modifications of graphyne: α-, β1-, β2-, β3-, γ1-, γ2-, and γ3-graphyne. Polymorphic modifications β3 graphyne and γ3 graphyne are described. The basic structural modifications of graphyne contain diatomic polyyne chains and consist only of carbon atoms in two different crystallographically equivalent states. Other nonbasic structural modifications of graphyne can be formed via the elongation of the carbyne chains that connect three-coordinated carbon atoms and via the formation of graphyne layers with a mixed structure consisting of basic layer fragments, such as α-β-graphyne, α-γ-graphyne, and β-γ-graphyne. The semiempirical quantum-mechanical MNDO, AM1, and PM3 methods and ab initio STO6-31G basis calculations are used to find geometrically optimized structures of the basic graphyne layers, their structural parameters, and energies of their sublimation. The energy of sublimation is found to be maximal for γ2-graphyne, which should be the most stable structural modification of graphyne.
Hybrid-structure atomic models for HED laboratory plasma diagnostics and simulations
Hansen, Stephanie
2010-03-01
While theoretical atomic physics calculations are well developed for isolated atoms and have been thoroughly benchmarked against low-density laboratory sources such as electron beam ion traps and tokamak plasmas, the high energy density (HED) regime offers significant challenges for atomic physics and spectroscopic modeling. High plasma densities lead to collective effects such as continuum lowering, line broadening, and significant populations in multiply excited atomic states. These effects change the plasma equation of state and the character of emission and absorption spectra and must be accounted for in order to accurately simulate radiative transfer in and apply spectroscopic diagnostics to HED plasmas. Modeling complex mid- and high-Z ions in the HED regime is a particular challenge because exponential growth in accessible configuration space overwhelms the reduction of the Rydberg levels through continuum lowering. This talk will discuss one approach to generating a tractable spectroscopic-quality atomic kinetics model and describe its application to HED laboratory plasmas produced on Sandia's Z facility. [4pt] Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
自旋-轨道耦合下冷原子的双反射∗%Double reflection of spin-orbit-coupled cold atoms
Institute of Scientific and Technical Information of China (English)
黄珍; 曾文; 古艺; 刘利; 周鲁; 张卫平
2016-01-01
随着中性冷原子气体的人造自旋-轨道耦合的实验实现，近年来人们开始关注与之相关的可能应用，其中包括自旋-轨道耦合下原子反射镜的研究。本文在前人研究的基础上，考虑一束自旋-轨道耦合的冷原子气体入射到有限高势垒的情形，通过将部分反射和全反射情况进行对比，发现了与之前研究不同的性质。我们发现，在全反射条件下，反射原子的极化率随入射角变化较大，而随自旋-轨道耦合强度和原子入射能量的变化较小。但在发生部分反射的情况下，反射原子的极化率不仅随入射角变化较大，随自旋-轨道耦合强度和原子的入射能量变化也十分明显。我们仔细研究了自旋-轨道耦合原子气体的反射性质并讨论了其可能的应用。%Artificial spin-orbit coupling in neutral cold atom have been experimentally implemented in alkali-metal atoms. Nowadays people begin to explore its possible applications. One of the most interesting applications is the atomic mirror, which is a key element in atom optics. And spin-orbit coupling provides the atomic beam with the possibility that the atomic spin can flip during its propagation, thus can be used to prepare the quantum-state-selective atomic mirror. In 2008, Juzeliūnas, et al. [Juzeliūnas G, et al. 2008 Phys. Rev. Lett. 100 200405] studied a spin-orbit-coupled matter wave packet of cold atom gas impinging on an infinite step potential created by the optical light field. Results showed that there is not only ordinary specular reflection, but also non-specular one. The reflected atoms split into two beams and double reflection takes place. Based on the previous study, here we consider a matter wave packet of spin-orbit-coupled cold atom gas impinging on a finite step potential created by the optical light field. Due to the effect of the spin-orbit coupling, in addition to the propagating state, the eigenstates of cold atoms
Loibl, Stefan; Schütz, Martin
2012-08-28
An efficient method for the calculation of nuclear magnetic resonance (NMR) shielding tensors is presented, which treats electron correlation at the level of second-order Mo̸ller-Plesset perturbation theory. It uses spatially localized functions to span occupied and virtual molecular orbital spaces, respectively, which are expanded in a basis of gauge including atomic orbitals (GIAOs or London atomic orbitals). Doubly excited determinants are restricted to local subsets of the virtual space and pair energies with an interorbital distance beyond a certain threshold are omitted. Furthermore, density fitting is employed to factorize the electron repulsion integrals. Ordinary Gaussians are employed as fitting functions. It is shown that the errors in the resulting NMR shielding constant, introduced (i) by the local approximation and (ii) by density fitting, are very small or even negligible. The capabilities of the new program are demonstrated by calculations on some extended molecular systems, such as the cyclobutane pyrimidine dimer photolesion with adjacent nucleobases in the native intrahelical DNA double strand (ATTA sequence). Systems of that size were not accessible to correlated ab initio calculations of NMR spectra before. The presented method thus opens the door to new and interesting applications in this area.
Reinhardt, William P.; Perry, Heidi
2003-01-01
The possibility, envisaged in 1925 by Einstein following the suggestion of Bose, of a dilute gas of atoms being condensed into a single quantum state was experimentally achieved in 1995 following decades of research. An avalanche of experiment and theory has followed, leading to the awarding of the 2001 Nobel Prizes in Physics to three of the pioneering experimentalists. Theory, mostly couched in the language and formalism of condensed matter physics, has developed apace. What we point out he...
元素轨道电负性与原子轨道能级%The Element Orbital Electronegativity and Atomic Orbital Energy Levels
Institute of Scientific and Technical Information of China (English)
李国英
2001-01-01
A new orbital electronegativity scale has been offered. The new scale with clear physical meaning is more reasonable than other scale. Its method of calculation is much simpler.% 根据价轨道的能量，建立了一种新的元素轨道电负性标度，新标度的物理意义明确，方法简单，数值合理，数据完整。并且给出了一些分子(或基团)的轨道电负性值。
Fu, Mingkai; Ma, Haitao; Cao, Jianwei; Bian, Wensheng
2017-04-07
Owing to the exciting potential applications of ultracold atoms and molecules in many fields, developing new cooling schemes has attracted great interests in recent years. Here, we investigate laser cooling of CaBr molecules and design a photonic scheme for the production of ultracold Br atoms using the highly accurate ab initio and dynamical methods. We find that the AΠ1/22(ν(')=0)→X(2)Σ1/2(+)(ν=0) transition for CaBr features a large vibrational branching ratio, a significant photon-scattering rate, and no intermediate electronic-state interference, indicating that the ultracold CaBr could be produced through a three-laser cooling scheme. Moreover, an efficient four-pulse excitation scheme from the ground rovibrational level of the cooled CaBr molecules is proposed to yield ultracold Br atoms, in which a few spin-orbit excited states are utilized as the intermediate states. The importance of the spin-orbit coupling is underscored in this work.
Holmstrom, M; Barabash, S; Brinkfeldt, K; Moore, T E; Simpson, D
2007-01-01
The low energy neutral atom imagers on Mars Express and IMAGE have revealed that the neutral atom populations in interplanetary space come from a variety of sources and challenge our current understanding of heliospheric physics. For example, both in cruise phase and at Mars, the neutral particle instrument NPD on Mars Express observed "unexplained neutral beams" unrelated to Mars which appear to be either of heliospheric or solar wind origin. Likewise, the NPI instrument on Mars Express has revealed streams of neutral atoms with different properties than those observed by NPD. Independently, IMAGE/LENA has reported neutral atom observations that may be interpreted as a "secondary stream" having different characteristics and flowing from a higher ecliptic longitude than the nominal upstream direction. Both sets of observations do not appear to fit in easily with the neutral atom environment from 1.0-1.57 AU as it is currently understood. In this paper we examine some highly suggestive similarities in the IMAG...
Mignolet, B.; Remacle, F.
2016-12-01
Fullerenes have a dense manifold of excited states composed of valence excited states and Rydberg states. Among Rydberg states, one distinguishes Super Atom Molecular Orbitals (SAMO), excited states in which an electron is promoted to a diffuse nanometer size molecular orbital with a hydrogenic-like character. Unlike typical Rydberg states, the electronic density of the SAMO states is mainly localized inside and in the close vicinity of the fullerene cage. In this proceeding, we propose a time-saving way to compute the electronic structure of the SAMO and Rydberg states of fullerenes at the TDDFT level by limiting the number of excitations allowed to build the excited states. We investigate the effect of limiting the number of excitations in C60 and compare it to the experimental binding energies. We also investigate the effect of the functional and basis set on the binding energies of the SAMO states.
Zhang, Hao; Ding, He; Wei, Mengjie; Li, Chunya; Wei, Bin; Zhang, Jianhua
2015-01-01
A hybrid nanolaminates consisting of Al2O3/ZrO2/alucone (aluminum alkoxides with carbon-containing backbones) grown by atomic layer deposition (ALD) were reported for an encapsulation of organic light-emitting diodes (OLEDs). The electrical Ca test in this study was designed to measure the water vapor transmission rate (WVTR) of nanolaminates. We found that moisture barrier performance was improved with the increasing of the number of dyads (Al2O3/ZrO2/alucone) and the WVTR reached 8.5 × 10(-5) g/m(2)/day at 25°C, relative humidity (RH) 85%. The half lifetime of a green OLED with the initial luminance of 1,500 cd/m(2) reached 350 h using three pairs of the Al2O3 (15 nm)/ZrO2 (15 nm)/alucone (80 nm) as encapsulation layers.
Zhu, Yizhou; Liu, Xiangmei; Yeung, Kelvin W. K.; Chu, Paul K.; Wu, Shuilin
2017-04-01
One-dimensional (1D) nanostructures of ZnO using atomic layer deposition (ALD) on chitosan (CS) modified carbon nanotubes (CNTs) were first introduced onto the surfaces of biomedical implants. When the content of ZnO is not sufficient, CNTs can strengthen the antibacterial activity against E. coli and S. aureus by 8% and 39%, respectively. CS can improve the cytocompatibility of CNTs and ZnO. The amount of Zn content can be controlled by changing the cycling numbers of ALD processes. This hybrid coating can not only endow medical implants with high self-antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) of over 73% and 98%, respectively, but also regulate the proliferation and osteogenic differentiation of osteoblasts by controlling the amount of ZnO.
Krishtal, Alisa; Van Alsenoy, Christian
2010-01-01
Holas and March (Phys. Rev. A51, 2040 (1995)) wrote the gradient of the one-body potential V(r) in terms of low-order derivatives of the idempotent Dirac density matrix built from a single Slater determinant of Kohn-Sham orbitals. Here, this is first combined with the study of Dawson and March (J. Chem. Phys. 81, 5850 (1984)) to express the single-particle kinetic energy density of the Be atom ground-state in terms of both the electron density n(r) and potential V(r). While this is the more compact formulation, we then, by removing V(r), demonstrate that the ratio t(r)/n(r) depends, though non-locally, only on the single variable n'(r)/n(r), no high-order gradients entering for the spherical Be atom.
Coherent Atom-Phonon Interaction through Mode Field Coupling in Hybrid Optomechanical Systems
Cotrufo, Michele; Verhagen, Ewold
2016-01-01
We propose a novel type of optomechanical coupling which enables a tripartite interaction between a quantum emitter, an optical mode and a macroscopic mechanical oscillator. The interaction uses a mechanism we term mode field coupling: mechanical displacement modifies the spatial distribution of the optical mode field, which in turn modulates the atom-photon coupling rate. In properly designed multimode optomechanical systems, we can achieve situations in which mode field coupling is the only possible interaction pathway for the system. This enables, for example, swapping of a single excitation between emitter and phonon, creation of nonclassical states of motion and mechanical ground-state cooling in the bad-cavity regime. Importantly, the emitter-phonon coupling rate can be enhanced through an optical drive field, allowing active control of strong atom-phonon coupling for realistic experimental parameters.
Entanglement of two hybrid optomechanical cavities composed of BEC atoms under Bell detection
Eghbali-Arani, M.; Ameri, V.
2017-02-01
In this paper, firstly, we consider bipartite entanglement between each part of an optomechanical cavity composed of one-dimensional Bose-Einstein condensate (BEC). We investigate atomic collision on the behaviour of the BEC in the week photon-atom coupling constant and use Bogoliubov approximation for the BEC. Secondly under above condition, we propose a scheme for entanglement swapping protocol which involves tripartite systems. In our investigation, we consider a scenario where BECs, moving mirrors, and optical cavity modes are given in a Gaussian state with a covariance matrix. By applying the Bell measurement to the output optical field modes, we show how the remote entanglement between two BECs, two moving mirrors, and BEC-mirror modes in different optomechanical cavity can be generated.
Towards hybrid quantum systems: Trapping a single atom near a nanoscale solid-state structure
Directory of Open Access Journals (Sweden)
Tiecke T.G.
2013-08-01
Full Text Available We describe and demonstrate a method to deterministically trap single atoms near nanoscale solid-state objects. The trap is formed by the interference of an optical tweezer and its reflection from the nano object, creating a one-dimensional optical lattice where the first lattice site is at z0 ∼ λ/4 from the surface. Using a tapered optical fiber as the nanoscopic object, we characterize the loading into different lattice sites by means of the AC-Stark shift induced by a guided fiber mode. We demonstrate a loading efficiency of 94(6% into the first lattice site, and measure the cooperativity for the emission of the atom into the guided mode of the nanofiber. We show that by tailoring the dimensions of the nanofiber the distance of the trap to the surface can be adjusted. This method is applicable to a large variety of nanostructures and represents a promising starting point for interfacing single atoms with arbitrary nanoscale solid-state systems.
Indian Academy of Sciences (India)
AMLAN GARAI; SUBHADIP PAL; SUDEEPTA MONDAL; SHINJAN GHOSH; SWARNENDU SEN; ACHINTYA MUKHOPADHYAY
2017-04-01
Gas turbines have wide application as prime movers in transportation and power generating sectors,most of which are driven by fossil fuels like kerosene. The conventional fuels are associated with problems of air pollution, and the fuel reserves are getting depleted gradually. Addition of ethanol in kerosene leads to better spraying characteristics. The present work deals with the spray characteristics of pure kerosene and 10%-ethanol-blended (by volume) kerosene using a novel gas-turbine hybrid atomizer. Here the inner air and outer airenter in the same and opposite directions, respectively, with respect to the fuel flow direction into the atomizer and a high swirling effect occurs outside the nozzle. The fuel stream is sandwiched between two annular air streams and the flow rate of inner and outer air is varied continuously. Various spray stages like distorted pencil,onion, tulip and fully developed spray regimes have been observed. The breakup length, cone angle and sheet width of the fuel stream are analysed directly from backlit imaging for different fuel and air flow rates. From the image processing, it is observed that breakup occurs at an early stage for 10%-ethanol-blended kerosene due to low viscosity of ethanol. It is also observed that at higher air flow rate, breakup occurs at an early stage due toturbulent nature of the fuel stream.
Conceptual Integration of Hybridization by Algerian Students Intending to Teach Physical Sciences
Salah, Hazzi; Dumon, Alain
2011-01-01
This work aims to assess the difficulties encountered by students of the Ecole Normale Superieure of Kouba (Algeria) intending to teach physical science in the integration of the hybridization of atomic orbitals. It is a concept that they should use in describing the formation of molecular orbitals ([sigma] and [pi]) in organic chemistry and gaps…
Conceptual Integration of Hybridization by Algerian Students Intending to Teach Physical Sciences
Salah, Hazzi; Dumon, Alain
2011-01-01
This work aims to assess the difficulties encountered by students of the Ecole Normale Superieure of Kouba (Algeria) intending to teach physical science in the integration of the hybridization of atomic orbitals. It is a concept that they should use in describing the formation of molecular orbitals ([sigma] and [pi]) in organic chemistry and gaps…
Pakniat, R.; Tavassoly, M. K.; Zandi, M. H.
2017-01-01
In this paper, we outline a scheme for entanglement swapping based on the concept of cavity QED. The atom-field entangled state in our study is produced in the nonlinear regime. In this scheme, the exploited cavities are prepared in a hybrid entangled state (a combination of coherent and number states) and the swapping process is investigated using two different methods, i.e., detecting and Bell-state measurement methods through the cavity QED. Then, we make use of the atom-field entangled state obtained by detecting method to show that how the atom-atom entanglement as well as atomic and field states teleportation can be achieved with complete fidelity.
Sugisaki, Kenji; Toyota, Kazuo; Sato, Kazunobu; Shiomi, Daisuke; Kitagawa, Masahiro; Takui, Takeji
2010-10-04
Zero-field splitting (ZFS) tensors (D tensors) of organic high-spin oligonitrenes/oligocarbenes up to spin-septet are quantitatively determined on the basis of quantum chemical calculations. The spin-orbit contributions, D(SO) tensors are calculated in terms of a hybrid CASSCF/MRMP2 approach, which was recently proposed by us. The spin-spin counterparts, D(SS) tensors are computed based on McWeeny-Mizuno's equation in conjunction with the RODFT spin densities. The present calculations show that more than 10% of ZFS arises from spin-orbit interactions in the high-spin nitrenes under study. Contributions of spin-bearing site-site interactions are estimated with the aid of a semi-empirical model for the D tensors and found to be ca. 5% of the D(SO) tensor. The analysis of intermediate states reveal that the largest contributions to the calculated D(SO) tensors are attributed to intra-site spin flip excitations and delocalized π and π* orbitals play an important role in the inter-site spin-orbit interactions.
Aringazin, A. K.
2002-01-01
In this paper we overview some results on the hydrogen atom in external static uniform magnetic fields. We focus on the case of very strong magnetic field, B>>B_0=2.3x10^9 Gauss, use various approximate models and, particularly, in the adiabatic approximation have calculated exactly the integral defining the effective potential. This potential appears to be finite at z=0. Our consideration of the problem of highly magnetized atoms and molecules is motivated by the recently developed MagneGas ...
Institute of Scientific and Technical Information of China (English)
CHEN LaiWen; WANG JingHua; LEE Chun-Hian
2009-01-01
When hyperthermal atomic oxygen collides with a silicon surface, an ultrathin oxidation regime characterized by fractional atomic-oxygen anions having low diffusive and reactive barriers, along with their enhanced diffusion due to both the electric field and image potential, will form on the surface. In accordance with these properties, an attempt was made in the present study to modify the AlmeidaGoncalves-Baumvol (AGB) model by setting the diffusivity and reaction rate constant to be diffusion-length dependence. According to the modified model, numerical parametric studies for oxidation thin growth were performed. The dependencies of the diffusion coefficient, the reaction rate constant,the attenuation length, and the adjustable parameter upon the translational kinetic energy, flux, temperature, and tangential flux of atomic oxygen were analyzed briefly via the fitting of the experimental data given by Tagawa et al. The numerical results confirmed the rationality of the modified diffusion-reaction model. The model together with the computer code developed in this study would be a useful tool for thickness evaluation of the protective film against the oxidation of atomic oxygen toward spacecraft surface materials in LEO environment.
Institute of Scientific and Technical Information of China (English)
LEE; Chun-Hian
2009-01-01
When hyperthermal atomic oxygen collides with a silicon surface, an ultrathin oxidation regime characterized by fractional atomic-oxygen anions having low diffusive and reactive barriers, along with their enhanced diffusion due to both the electric field and image potential, will form on the surface. In ac- cordance with these properties, an attempt was made in the present study to modify the Almeida- Goncalves-Baumvol (AGB) model by setting the diffusivity and reaction rate constant to be diffu- sion-length dependence. According to the modified model, numerical parametric studies for oxidation thin growth were performed. The dependencies of the diffusion coefficient, the reaction rate constant, the attenuation length, and the adjustable parameter upon the translational kinetic energy, flux, tem- perature, and tangential flux of atomic oxygen were analyzed briefly via the fitting of the experimental data given by Tagawa et al. The numerical results confirmed the rationality of the modified diffu- sion-reaction model. The model together with the computer code developed in this study would be a useful tool for thickness evaluation of the protective film against the oxidation of atomic oxygen toward spacecraft surface materials in LEO environment.
The rehybridization of electronic orbitals in carbon nanotubes
Institute of Scientific and Technical Information of China (English)
Ouyang Yu; Peng Jing-Cui; Wang Hui; Peng Zhi-Hua
2008-01-01
Rehybridization of electronic orbitals in carbon nanotubes contains tilting angles of π orbital, electrons wavefunc-tions of π orbital and σ orbital, degrees of hybridization, etc. In this paper, we have obtained analytical formulas of tilting angle of π orbital relative to tube surface, electrons wavefunctions of π orbital and σ orbital, degrees of hybridization, separately, as well as the numerical results.
Tsuzuki, Seiji; Hayamizu, Kikuko; Seki, Shiro; Ohno, Yasutaka; Kobayashi, Yo; Miyashiro, Hajime
2008-08-14
Interactions of the lithium bis(trifluoromethylsulfonyl)amide (LiTFSA) complex with N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium (DEME), 1-ethyl-3-methylimidazolium (EMIM) cations, neutral diethylether (DEE), and the DEMETFSA complex were studied by ab initio molecular orbital calculations. An interaction energy potential calculated for the DEME cation with the LiTFSA complex has a minimum when the Li atom has contact with the oxygen atom of DEME cation, while potentials for the EMIM cation with the LiTFSA complex are always repulsive. The MP2/6-311G**//HF/6-311G** level interaction energy calculated for the DEME cation with the LiTFSA complex was -18.4 kcal/mol. The interaction energy for the neutral DEE with the LiTFSA complex was larger (-21.1 kcal/mol). The interaction energy for the DEMETFSA complex with LiTFSA complex is greater (-23.2 kcal/mol). The electrostatic and induction interactions are the major source of the attraction in the two systems. The substantial attraction between the DEME cation and the LiTFSA complex suggests that the interaction between the Li cation and the oxygen atom of DEME cation plays important roles in determining the mobility of the Li cation in DEME-based room temperature ionic liquids.
Indian Academy of Sciences (India)
Xiqian Niu; Zhengguo Huang; Lingling Ma; Tingting Shen; Lingfei Guo
2013-07-01
The tryptophan-water (Trp-H2O) complexes formed by hydrogen bonding interactions were investigated at the B97XD/6-311++G(d,p) level. Five Trp-H2O complexes possessing various types of hydrogen bonds (H-bonds) were characterized by geometries, energies, vibrational frequencies. The nature of the H-bonds were characterized by the natural bond orbital (NBO) and the quantum theory of atoms in molecule (QTAIM) analyses as well. The intramolecular H-bond formed between the amino and carboxyl oxygen atom of tryptophan was retained in most of the complexes, and the cooperativity between the intra and intermolecular H-bonds exist in some complexes. The intramolecular H-bond and some intermolecular H-bonds are strong and have partial covalent character. The H-bonds formed between carboxyl and oxygen/nitrogen atoms are stronger than other H-bonds. The H-bonds involving methylene of tryptophan as H-donor are weak H-bonds. For all complexes,ele and ex makes major contributions to the total interaction energy (MP2), while disp is the smallest component of the interaction energy. Both hydrogen bonding interaction and structural deformation play important roles in the relative stabilities of the complexes. Regardless of strong H-bonds, the stabilities of some complexes are weakened by the serious structural deformations.
Energy Technology Data Exchange (ETDEWEB)
Sanfilippo, Andrea; Ren, Xinguo; Tkatchenko, Alexandre; Blum, Volker; Reuter, Karsten; Scheffler, Matthias [Fritz-Haber-Institut, Berlin (Germany); Rinke, Patrick [Fritz-Haber-Institut, Berlin (Germany); University of California, Santa Barbara, CA (United States)
2008-07-01
Well known deficiencies of present-day exchange-correlation functionals in density-functional theory (DFT) comprise the spurious self-interaction, the absence of non-local correlation (van der Waals, image interactions), and the absence of the derivative discontinuity with respect to changes in the electron number. We present a unified framework to overcome these deficiencies by many-body perturbation theory in the bare (Hartree-Fock,MP2) and the screened Coulomb interaction (Hedin's GW approximation). Using numeric atomic-centered orbitals as basis sets, the efficiency of our formulation relies on the representation of intermediate quantities like the polarizability, and bare and screened Coulomb potentials by a second, auxiliary set of atom-centered basis functions. For an extended set of finite systems spanning individual atoms, small molecules (water dimer, methane, silane, benzene), metal clusters (Na{sub n}), and biomolecules (alanine) we demonstrate that our implementation in the new DFT code FHI-aims is significantly more efficient than existing formulations based on traditional plane wave or Gaussian basis sets.
Lee, Byungho; Lee, Sangheon; Cho, Duckhyung; Kim, Jinhyun; Hwang, Taehyun; Kim, Kyung Hwan; Hong, Seunghun; Moon, Taeho; Park, Byungwoo
2016-11-16
Organic-inorganic hybrid perovskite solar cells have emerged as promising candidates for next-generation solar cells. To attain high photovoltaic efficiency, reducing the defects in perovskites is crucial along with a uniform coating of the films. Also, evaluating the quality of synthesized perovskites via facile and adequate methods is important as well. Herein, CH3NH3PbI3 perovskites were synthesized by applying second solvent dripping to nonstoichiometric precursors containing excess CH3NH3I. The resulting perovskite films exhibited a larger average grain size with a better crystallinity compared to that from stoichiometric precursors. As a result, the performance of planar perovskite solar cells was significantly improved, achieving an efficiency of 14.3%. Furthermore, perovskite films were effectively analyzed using a conductive AFM and noise spectroscopy, which have been uncommon in the field of perovskite solar cells. Comparing the topography and photocurrent maps, the variation of photocurrents in nanoscale was systematically investigated, and a linear relationship between the grain size and photocurrent was revealed. Also, noise analyses with a conductive probe enabled examination of the defect density of perovskites at specific grain interiors by excluding the grain-boundary effect, and reduced defects were clearly observed for the perovskites using CH3NH3I-rich precursors.
Hybrid-PIC Modeling of the Transport of Atomic Boron in a Hall Thruster
Smith, Brandon D.; Boyd, Iaian D.; Kamhawi, Hani
2015-01-01
Computational analysis of the transport of boron eroded from the walls of a Hall thruster is performed by implementing sputter yields of hexagonal boron nitride and velocity distribution functions of boron within the hybrid-PIC model HPHall. The model is applied to simulate NASA's HiVHAc Hall thruster at a discharge voltage of 500V and discharge powers of 1-3 kW. The number densities of ground- and 4P-state boron are computed. The density of ground-state boron is shown to be a factor of about 30 less than the plasma density. The density of the excited state is shown to be about three orders of magnitude less than that of the ground state, indicating that electron impact excitation does not significantly affect the density of ground-state boron in the discharge channel or near-field plume of a Hall thruster. Comparing the rates of excitation and ionization suggests that ionization has a greater influence on the density of ground-state boron, but is still negligible. The ground-state boron density is then integrated and compared to cavity ring-down spectroscopy (CRDS) measurements for each operating point. The simulation results show good agreement with the measurements for all operating points and provide evidence in support of CRDS as a tool for measuring Hall thruster erosion in situ.
Tunable High Q Superconducting Microwave Resonator for Hybrid System with ^87Rb atoms
Kim, Zaeill; Voigt, K. D.; Lee, Jongmin; Hoffman, J. E.; Grover, J. A.; Ravets, S.; Zaretskey, V.; Palmer, B. S.; Hafezi, M.; Taylor, J. M.; Anderson, J. R.; Dragt, A. J.; Lobb, C. J.; Orozco, L. A.; Rolston, S. L.; Wellstood, F. C.
2012-02-01
We have developed a frequency tuning system for a ``lumped-element'' thin-film superconducting Al microwave resonator [1] on sapphire intended for coupling to hyperfine ground states of cold trapped ^87Rb atoms, which are separated by about fRb=6.83 GHz. At T=12 mK and on resonance at 6.81 GHz, the loaded quality factor was 120,000. By moving a carefully machined Al pin towards the inductor of the resonator using a piezo stage, we were able to tune the resonance frequency over a range of 35 MHz and within a few kHz of fRb. While measuring the power dependent response of the resonator at each tuned frequency, we observed anomalous decreases in the quality factor at several frequencies. These drops were more pronounced at lower power. We discuss our results, which suggest these resonances are attributable to discrete two-level systems.[4pt] [1] Z. Kim et al., AIP ADVANCES 1, 042107 (2011).
Energy Technology Data Exchange (ETDEWEB)
Hernando, Antonio; Crespo, Patricia [Instituto de Magnetismo Aplicado, UCM-CSIC-ADIF, Las Rozas. P.O. Box 155, 28230 Madrid (Spain); Dept. Fisica de Materiales, Universidad Complutense, Madrid (Spain); Garcia, Miguel Angel [Instituto de Ceramica y Vidrio, CSIC, C/ Kelsen, 5, Madrid 28049 (Spain); Coey, Michael [Trinity College Dublin, Dublin (Ireland); Ayuela, Andres; Echenique, Pedro Miguel [Centro de Fisica de Materiales, CFM-MPC CSIC-UPV/EHU, Donostia International Physics Center (DIPC), 20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Fac. de Quimicas, Universidad del Pais Vasco UPV-EHU, 20018 San Sebastian (Spain)
2011-10-15
In this article we review the exotic magnetism of nanoparticles (NPs) formed by substances that are not magnetic in bulk as described with generality in Section 1. In particular, the intrinsic character of the magnetism observed on capped Au and ZnO NPs is analysed. X-ray magnetic circular dichroism (XMCD) analysis has shown that the magnetic moments are intrinsic and lie in the Au and Zn atoms, respectively, as analysed in Section 2, where the general theoretical ideas are also revisited. Since impurity atoms bonded to the surface act as donor or acceptor of electrons that occupy the surface states, the anomalous magnetic response is analysed in terms of the surface band in Section 3. Finally, Section 4 summarizes our last theoretical proposal. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Vardimon, R.; Matt, M.; Nielaba, P.; Cuevas, J. C.; Tal, O.
2016-02-01
With the goal of elucidating the nature of spin-dependent electronic transport in ferromagnetic atomic contacts, we present here a combined experimental and theoretical study of the conductance and shot noise of metallic atomic contacts made of the 3 d ferromagnetic materials Fe, Co, and Ni. For comparison, we also present the corresponding results for the noble metal Cu. Conductance and shot noise measurements, performed using a low-temperature break-junction setup, show that in these ferromagnetic nanowires, (i) there is no conductance quantization of any kind, (ii) transport is dominated by several partially open conduction channels, even in the case of single-atom contacts, and (iii) the Fano factor of large contacts saturates to values that clearly differ from those of monovalent (nonmagnetic) metals. We rationalize these observations with the help of a theoretical approach that combines molecular dynamics simulations to describe the junction formation with nonequilibrium Green's function techniques to compute the transport properties within the Landauer-Büttiker framework. Our theoretical approach successfully reproduces all the basic experimental results and it shows that all the observations can be traced back to the fact that the d bands of the minority-spin electrons play a fundamental role in the transport through ferromagnetic atomic-size contacts. These d bands give rise to partially open conduction channels for any contact size, which in turn lead naturally to the different observations described above. Thus, the transport picture for these nanoscale ferromagnetic wires that emerges from the ensemble of our results is clearly at variance with the well established conduction mechanism that governs the transport in macroscopic ferromagnetic wires, where the d bands are responsible for the magnetism but do not take part in the charge flow. These insights provide a fundamental framework for ferromagnetic-based spintronics at the nanoscale.
Hancox, Cindy I; Doret, S Charles; Hummon, Matthew T; Krems, Roman V; Doyle, John M
2005-01-14
The Zeeman relaxation rate in cold collisions of Ti(3d(2)4s(2) 3F2) with He is measured. We find that collisional transfer of angular momentum is dramatically suppressed due to the presence of the filled 4s(2) shell. The degree of electronic interaction anisotropy, which is responsible for Zeeman relaxation, is estimated to be about 200 times smaller in the Ti-He complex than in He complexes with typical non-S-state atoms.
Shen, Lin; Yang, Weitao
2016-04-12
We developed a new multiresolution method that spans three levels of resolution with quantum mechanical, atomistic molecular mechanical, and coarse-grained models. The resolution-adapted all-atom and coarse-grained water model, in which an all-atom structural description of the entire system is maintained during the simulations, is combined with the ab initio quantum mechanics and molecular mechanics method. We apply this model to calculate the redox potentials of the aqueous ruthenium and iron complexes by using the fractional number of electrons approach and thermodynamic integration simulations. The redox potentials are recovered in excellent accordance with the experimental data. The speed-up of the hybrid all-atom and coarse-grained water model renders it computationally more attractive. The accuracy depends on the hybrid all-atom and coarse-grained water model used in the combined quantum mechanical and molecular mechanical method. We have used another multiresolution model, in which an atomic-level layer of water molecules around redox center is solvated in supramolecular coarse-grained waters for the redox potential calculations. Compared with the experimental data, this alternative multilayer model leads to less accurate results when used with the coarse-grained polarizable MARTINI water or big multipole water model for the coarse-grained layer.
Maurer, Marina; Ochsenfeld, Christian
2013-05-07
An atomic-orbital (AO) based formulation for calculating nuclear magnetic resonance chemical shieldings at the second-order Møller-Plesset perturbation theory level is introduced, which provides a basis for reducing the scaling of the computational effort with the molecular size from the fifth power to linear and for a specific nucleus to sublinear. The latter sublinear scaling in the rate-determining steps becomes possible by avoiding global perturbations with respect to the magnetic field and by solving for quantities that involve the local nuclear magnetic spin perturbation instead. For avoiding the calculation of the second-order perturbed density matrix, we extend our AO-based reformulation of the Z-vector method within a density matrix-based scheme. Our pilot implementation illustrates the fast convergence with respect to the required number of Laplace points and the asymptotic scaling behavior in the rate-determining steps.
Kumar, Chandan; Kjærgaard, Thomas; Helgaker, Trygve; Fliegl, Heike
2016-12-21
An atomic orbital density matrix based response formulation of the nuclei-selected approach of Beer, Kussmann, and Ochsenfeld [J. Chem. Phys. 134, 074102 (2011)] to calculate nuclear magnetic resonance (NMR) shielding tensors has been developed and implemented into LSDalton allowing for a simultaneous solution of the response equations, which significantly improves the performance. The response formulation to calculate nuclei-selected NMR shielding tensors can be used together with the density-fitting approximation that allows efficient calculation of Coulomb integrals. It is shown that using density-fitting does not lead to a significant loss in accuracy for both the nuclei-selected and the conventional ways to calculate NMR shielding constants and should thus be used for applications with LSDalton.
Sure, Rebecca; Brandenburg, Jan Gerit; Grimme, Stefan
2016-04-01
In quantum chemical computations the combination of Hartree-Fock or a density functional theory (DFT) approximation with relatively small atomic orbital basis sets of double-zeta quality is still widely used, for example, in the popular B3LYP/6-31G* approach. In this Review, we critically analyze the two main sources of error in such computations, that is, the basis set superposition error on the one hand and the missing London dispersion interactions on the other. We review various strategies to correct those errors and present exemplary calculations on mainly noncovalently bound systems of widely varying size. Energies and geometries of small dimers, large supramolecular complexes, and molecular crystals are covered. We conclude that it is not justified to rely on fortunate error compensation, as the main inconsistencies can be cured by modern correction schemes which clearly outperform the plain mean-field methods.
Wang, Xiao; Zhang, Yue; Lv, Lihua; Cui, Yongzhu; Wei, Chunyan; Pang, Guibing
2016-02-01
Mg(OH)2 flame retardant hybrid pigment is synthesized through simultaneous solution precipitation and adsorption of anionic dyes (C.I. Acid Red 6). The Mg(OH)2 hybrid pigment bearing vinyl groups after surface silane modification is immobilized onto the surface of bromo end-functional cellulose fiber by atom transfer radical polymerization (ATRP). The morphology and structure of Mg(OH)2 pigments and cellulose fibers grafted with modified pigments are characterized. The thermal properties, flammability and color fastness of cellulose fibers grafted with modified pigments are measured. The results reveal that anionic dye molecules are adsorbed onto Mg(OH)2 crystals and affect the formation of lamella-like Mg(OH)2 crystals. The cellulose fiber grafted with modified Mg(OH)2 hybrid pigment absorbs about four times heat more than original cellulose fiber with about 4% immobilization ratio of pigment, which shortens nearly half of afterflame time and afterglow time.
Gervais, B; Zanuttini, D; Douady, J
2016-05-21
We analyze the role of the spin-orbit (SO) coupling in the dissociative dynamics of excited alkali atoms at the surface of small rare gas clusters. The electronic structure of the whole system is deduced from a one-electron model based on core polarization pseudo-potentials. It allows us to obtain in the same footing the energy, forces, and non-adiabatic couplings used to simulate the dynamics by means of a surface hopping method. The fine structure state population is analyzed by considering the relative magnitude of the SO coupling ξ, with respect to the spin-free potential energy. We identify three regimes of ξ-values leading to different evolution of adiabatic state population after excitation of the system in the uppermost state of the lowest np (2)P shell. For sufficiently small ξ, the final population of the J=12 atomic states, P12, grows up linearly from P12=13 at ξ = 0 after a diabatic dynamics. For large values of ξ, we observe a rather adiabatic dynamics with P12 decreasing as ξ increases. For intermediate values of ξ, the coupling is extremely efficient and a complete transfer of population is observed for the set of parameters associated to NaAr3 and NaAr4 clusters.
Gregory, J. C.; Raiker, G. N.; Bijvoet, J. A.; Nerren, P. D.; Sutherland, W. T.; Mogro-Camperso, A.; Turner, L. G.; Kwok, Hoi; Raistrick, I. D.; Cross, J. B.
1995-01-01
In 1992, UAH (University of Alabama in Huntsville) conducted a unique experiment on STS-46 in which YBa2Cu3O7 (commonly known as '1-2-3' superconductor) high-T(c) superconducting thin film samples prepared at three different laboratories were exposed to 5 eV atomic oxygen in low Earth orbit on the ambient and 320 C hot plate during the first flight of the CONCAP-2 (Complex Autonomous Payload) experiment carrier. The resistance of the thin films was measured in flight during the atomic oxygen exposure and heating cycle. Superconducting properties were measured in the laboratory before and after the flight by the individual experimenters. Films with good superconducting properties, and which were exposed to the oxygen flux, survived the flight including those heated to 320 C (600 K) with properties essentially unchanged, while other samples which were heated but not exposed to oxygen were degraded. The properties of other flight controls held at ambient temperature appear unchanged and indistinguishable from those of ground controls, whether exposed to oxygen or not.
Stability Analysis of the In-Orbit Satellite Atomic Clocks%GPS在轨卫星原子钟的稳定性分析
Institute of Scientific and Technical Information of China (English)
李长会; 闫国锋
2012-01-01
导航卫星星载原子钟的相位或频率数据,作为导航系统应用研究的基础,将直接影响导航系统时间尺度建立以及定位的精度和准确性.本文针对由IGS官网提供的四种GPS卫星钟的钟差数据,采用修正阿伦方差进行了稳定性分析,得到了一些有益的结论.%As the application research basis of navigation system, the phase or frequency data of in - orbit satellite atomic clocks directly affect the precision and accuracy of navigation system. This paper analyzes the stability of four types of data of GPS satellite a-tomic clocks which is provided by the official website of IGS using Allan variance method and reaches some beneficial conclusions.
Oikawa, Masahiro; Yoshiura, Koh-ichiro; Kondo, Hisayoshi; Miura, Shiro; Nagayasu, Takeshi; Nakashima, Masahiro
2011-12-07
It has been postulated that ionizing radiation induces breast cancers among atomic bomb (A-bomb) survivors. We have reported a higher incidence of HER2 and C-MYC oncogene amplification in breast cancers from A-bomb survivors. The purpose of this study was to clarify the effect of A-bomb radiation exposure on genomic instability (GIN), which is an important hallmark of carcinogenesis, in archival formalin-fixed paraffin-embedded (FFPE) tissues of breast cancer by using microarray-comparative genomic hybridization (aCGH). Tumor DNA was extracted from FFPE tissues of invasive ductal cancers from 15 survivors who were exposed at 1.5 km or less from the hypocenter and 13 calendar year-matched non-exposed patients followed by aCGH analysis using a high-density oligonucleotide microarray. The total length of copy number aberrations (CNA) was used as an indicator of GIN, and correlation with clinicopathological factors were statistically tested. The mean of the derivative log ratio spread (DLRSpread), which estimates the noise by calculating the spread of log ratio differences between consecutive probes for all chromosomes, was 0.54 (range, 0.26 to 1.05). The concordance of results between aCGH and fluorescence in situ hybridization (FISH) for HER2 gene amplification was 88%. The incidence of HER2 amplification and histological grade was significantly higher in the A-bomb survivors than control group (P = 0.04, respectively). The total length of CNA tended to be larger in the A-bomb survivors (P = 0.15). Correlation analysis of CNA and clinicopathological factors revealed that DLRSpread was negatively correlated with that significantly (P = 0.034, r = -0.40). Multivariate analysis with covariance revealed that the exposure to A-bomb was a significant (P = 0.005) independent factor which was associated with larger total length of CNA of breast cancers. Thus, archival FFPE tissues from A-bomb survivors are useful for genome-wide aCGH analysis. Our results suggested that A
Directory of Open Access Journals (Sweden)
Oikawa Masahiro
2011-12-01
Full Text Available Abstract Background It has been postulated that ionizing radiation induces breast cancers among atomic bomb (A-bomb survivors. We have reported a higher incidence of HER2 and C-MYC oncogene amplification in breast cancers from A-bomb survivors. The purpose of this study was to clarify the effect of A-bomb radiation exposure on genomic instability (GIN, which is an important hallmark of carcinogenesis, in archival formalin-fixed paraffin-embedded (FFPE tissues of breast cancer by using microarray-comparative genomic hybridization (aCGH. Methods Tumor DNA was extracted from FFPE tissues of invasive ductal cancers from 15 survivors who were exposed at 1.5 km or less from the hypocenter and 13 calendar year-matched non-exposed patients followed by aCGH analysis using a high-density oligonucleotide microarray. The total length of copy number aberrations (CNA was used as an indicator of GIN, and correlation with clinicopathological factors were statistically tested. Results The mean of the derivative log ratio spread (DLRSpread, which estimates the noise by calculating the spread of log ratio differences between consecutive probes for all chromosomes, was 0.54 (range, 0.26 to 1.05. The concordance of results between aCGH and fluorescence in situ hybridization (FISH for HER2 gene amplification was 88%. The incidence of HER2 amplification and histological grade was significantly higher in the A-bomb survivors than control group (P = 0.04, respectively. The total length of CNA tended to be larger in the A-bomb survivors (P = 0.15. Correlation analysis of CNA and clinicopathological factors revealed that DLRSpread was negatively correlated with that significantly (P = 0.034, r = -0.40. Multivariate analysis with covariance revealed that the exposure to A-bomb was a significant (P = 0.005 independent factor which was associated with larger total length of CNA of breast cancers. Conclusions Thus, archival FFPE tissues from A-bomb survivors are useful for
Rodriguez-Serrano, Angela; Rai-Constapel, Vidisha; Daza, Martha C; Doerr, Markus; Marian, Christel M
2015-05-07
The effect of substituting the intra-cyclic sulphur of thionine by oxygen (oxonine) and selenium (selenine) on the intersystem crossing (ISC) efficiency has been studied using high level quantum mechanical methods. The ISC rate constants are considerably increased when going from O towards Se while the fluorescence rate constants remain unchanged. For the three dyes, all accessible ISC channels are driven by vibronic spin-orbit coupling (SOC) between ππ* states. The interplay between the ground and low-lying excited states has been investigated in order to determine the dominant relaxation pathways. In oxonine the relaxation to the ground state after photoexcitation in water proceeds essentially via fluorescence from the S1(πHπL*) bright state (kF = 2.10 × 10(8) s(-1)), in agreement with the high experimental fluorescence quantum yield. In aqueous solution of thionine, the ISC rate constant (kISC ∼ 1 × 10(9) s(-1)) is one order of magnitude higher than fluorescence (kF = 1.66 × 10(8) s(-1)) which is consistent with its high triplet quantum yield observed in water (ϕT = 0.53). Due to a stronger vibronic SOC in selenine, the ISC rate is very high (kISC ∼ 10(10) s(-1)) and much faster than fluorescence (kF = 1.59 × 10(8) s(-1)). This suggests selenine-based dyes as very efficient triplet photosensitizers.
A Mathematical Approach to Hybridization
Matthews, P. S. C.; Thompson, J. J.
1975-01-01
Presents an approach to hybridization which exploits the similarities between the algebra of wave functions and vectors. This method will account satisfactorily for the number of orbitals formed when applied to hybrids involving the s and p orbitals. (GS)
Russo, Andrea; Rene, Cornelius; Coupland, Sarah E; Sagili, Suresh; Damato, Bertil
2012-01-01
Cytogenetic analysis has transformed the management of uveal melanoma in recent years and allows categorization of such tumors into low-grade tumors with a favorable prognosis and high-grade tumors that metastasize with a fatal outcome. The authors report the case of a 73-year-old man who presented with recurrent melanoma in his left socket, 26 years after enucleation for uveal melanoma. Chromosomal analysis by multiplex ligation-dependent probe amplification revealed partial loss of chromosome 3 and gains in chromosomes 6 and 8, which were missed with fluorescence in situ hybridization. The patient developed multiple liver metastases 14 months after orbital exenteration and died 8 months later. To the best of authors' knowledge, this is the first report of late recurrence of uveal melanoma after enucleation, in which multiplex ligation-dependent probe amplification chromosomal analysis has been used. The case also highlights the limitations of fluorescence in situ hybridization and the benefits of multiplex ligation-dependent probe amplification, which is more reliable at predicting survival.
Doser, Bernd; Lambrecht, Daniel S; Kussmann, Jörg; Ochsenfeld, Christian
2009-02-14
A Laplace-transformed second-order Moller-Plesset perturbation theory (MP2) method is presented, which allows to achieve linear scaling of the computational effort with molecular size for electronically local structures. Also for systems with a delocalized electronic structure, a cubic or even quadratic scaling behavior is achieved. Numerically significant contributions to the atomic orbital (AO)-MP2 energy are preselected using the so-called multipole-based integral estimates (MBIE) introduced earlier by us [J. Chem. Phys. 123, 184102 (2005)]. Since MBIE provides rigorous upper bounds, numerical accuracy is fully controlled and the exact MP2 result is attained. While the choice of thresholds for a specific accuracy is only weakly dependent upon the molecular system, our AO-MP2 scheme offers the possibility for incremental thresholding: for only little additional computational expense, the numerical accuracy can be systematically converged. We illustrate this dependence upon numerical thresholds for the calculation of intermolecular interaction energies for the S22 test set. The efficiency and accuracy of our AO-MP2 method is demonstrated for linear alkanes, stacked DNA base pairs, and carbon nanotubes: e.g., for DNA systems the crossover toward conventional MP2 schemes occurs between one and two base pairs. In this way, it is for the first time possible to compute wave function-based correlation energies for systems containing more than 1000 atoms with 10 000 basis functions as illustrated for a 16 base pair DNA system on a single-core computer, where no empirical restrictions are introduced and numerical accuracy is fully preserved.
Photoelectron imaging of small aluminum clusters: quantifying s-p hybridization.
Melko, Joshua J; Castleman, A W
2013-03-07
Photoelectron imaging experiments and detailed calculations are conducted on Al(n)(-) clusters (n = 3-6) and a calibration method is developed for connecting experimental observations of photoelectron angular distributions to theoretical predictions. It is shown that this method can be used to quantify the degree to which the molecular orbitals are built from s- or p-like atomic orbitals. The highest occupied molecular orbitals of these small aluminum clusters are found to contain varying degrees of s-p mixing, with Al(3)(-) containing the "most hybridized" orbital and Al(4)(-) containing the "least hybridized" orbital. It is shown experimentally that s-p hybridization is already present for the trimer species and, similar to other properties of small metal clusters, oscillates with cluster size.
Institute of Scientific and Technical Information of China (English)
金锐; 高翔; 曾德灵; 顾春; 岳现房; 李家明
2016-01-01
Ionized atoms widely exist in plasmas, and studies of properties of ionized atoms are the foundations of frontier science researches such as astrophysics and controlled nuclear fusions. For example, the information about the ground configurations of atoms is required for accurately calculating the physical quantities such as energy levels and dynamical processes. The configurations for different ionized atoms can be obtained with the photo-electron energy spectrum exper-iment, however it is very time-consuming to obtain so many data of all ions. Therefore the more economical theoretical study will be of great importance. As is well known, the configurations of neutral atoms can be determined according to Mendeleev order while those of highly ionized atoms are hydrogen-like due to the strong Coulombic potential of their nuclei. Then with the variations of ionization degree and atomic number along the periodic table, there would appear the interesting competitions between electronic orbitals. Although some theoretical results exist for ions 3 6 Z 6 118, 3 6 N e 6 105 (where Z is the atomic number and N e is the electron number), there are many errors in the results for highly ionized atoms. Therefore, the ground configurations of ionized atoms and their orbital competitions still deserve to be systematically studied. Based on the independent electron approximation, we calculate the energy levels of all possible competition con-figurations of all the neutral and ionized atoms in the extended periodic tables (2 6 Z 6 119) by Dirac-Slater method. Then the ground configurations are determined by calculating the chosen lowest total energy. The advantages of Dirac-Slater method are as follows. 1) It has been shown that the Dirac-Slater calculation is accurate enough for studying the ground properties of atoms, such as the 1st threshold, and that higher accuracy will be obtained for highly ionized atoms, because the electron correlation becomes less important. 2
Energy Technology Data Exchange (ETDEWEB)
Kumar, Arvind; Bansal, Ankushi; Behera, Babita; Jain, Suman L.; Ray, Siddharth S., E-mail: ssray@iip.res.in
2016-04-01
A ternary hybrid of graphene oxide-titania-polystyrene (GO-TiO{sub 2}-PS) nanocomposite is developed where polystyrene composition is regulated by controlling growth of polymer chains and nanoarchitectonics is discussed. Graphene Oxide-TiO{sub 2} (GO-TiO{sub 2}) nanocomposite is prepared by in-situ hydrothermal method and the surface is anchored with α-bromoisobutyryl bromide to activate GO-TiO{sub 2} as initiator for polymerization. In-situ grafting of polystyrene through surface initiated atom transfer radical polymerization (SI- ATRP) on this Br-functionalized nano-composite initiator yields GO-TiO{sub 2}-PS ternary hybrid. Varying the monomer amount and keeping the concentration of initiator constant, polystyrene chain growth is regulated with narrow poly-dispersivity to achieve desired composition. This composite is well characterized by various analytical techniques like FTIR, XRD, DSC, SEM, TEM, and TGA. - Highlights: • Nanocomposite of ternary hybrid of GO-TiO{sub 2} with polystyrene. • PS is surface grafted on GO-TiO{sub 2}. • Polymer chain lengths are well regulated by SI-ATRP living polymerization. • Thermal stability of this hybrid is relatively high.
Momeni, Mohammad R; Brown, Alex
2016-04-28
A series of 11 different boron-dipyrromethene (BODIPY) dimers is carefully examined by means of ab initio and Tamm-Dancoff approximated density functional theory methods. Vertical and 0-0 excitation energies along with the tetraradical character of these dimers are determined. Possible application of a series of linked dimers for photodynamic therapy (PDT) was investigated through computing their excitation energies, spin-orbit coupling matrix elements, and singlet-triplet energy gaps. Finally through a systematic investigation of a series of 36 different BODIPY and aza-BODIPY dimers, a new class of near-IR heavy atom free photosensitizers for PDT action is introduced.
Matsubara, Masahiko; Saniz, Rolando; Partoens, Bart; Lamoen, Dirk
2017-01-01
Abstract: We investigate the role of transition metal atoms of group V-b (V, Nb, and Ta) and VI-b (Cr, Mo, and W) as n- or p-type dopants in anatase TiO2 using thermodynamic principles and density functional theory with the HeydScuseriaErnzerhof HSE06 hybrid functional. The HSE06 functional provides a realistic value for the band gap, which ensures a correct classification of dopants as shallow or deep donors or acceptors. Defect formation energies and thermodynamic transition levels are calc...
Random phase approximation with second-order screened exchange for current-carrying atomic states
Zhu, Wuming; Zhang, Liang; Trickey, S. B.
2016-12-01
The direct random phase approximation (RPA) and RPA with second-order screened exchange (SOSEX) have been implemented with complex orbitals as a basis for treating open-shell atoms. Both RPA and RPA+SOSEX are natural implicit current density functionals because the paramagnetic current density implicitly is included through the use of complex orbitals. We confirm that inclusion of the SOSEX correction improves the total energy accuracy substantially compared to RPA, especially for smaller-Z atoms. Computational complexity makes post self-consistent-field (post-SCF) evaluation of RPA-type expressions commonplace, so orbital basis origins and properties become important. Sizable differences are found in correlation energies, total atomic energies, and ionization energies for RPA-type functionals evaluated in the post-SCF fashion with orbital sets obtained from different schemes. Reference orbitals from Kohn-Sham calculations with semi-local functionals are more suitable for RPA+SOSEX to generate accurate total energies, but reference orbitals from exact exchange (non-local) yield essentially energetically degenerate open-shell atom ground states. RPA+SOSEX correlation combined with exact exchange calculated from a hybrid reference orbital set (half the exchange calculated from exact-exchange orbitals, the other half of the exchange from orbitals optimized for the Perdew-Burke-Ernzerhof (PBE) exchange functional) gives the best overall performance. Numerical results show that the RPA-like functional with SOSEX correction can be used as a practical implicit current density functional when current effects should be included.
Yanar, Ufuk; Babür, Banu; Pekyılmaz, Damla; Yahaya, Issah; Aydıner, Burcu; Dede, Yavuz; Seferoğlu, Zeynel
2016-03-01
A colorimetric and fluorimetric fluorescent chemosensor (CT-2), having a coumarin ring as a signaling unit and an acetamido thiophene ring as an H-donor receptor, has been synthesized from amino derivative (CT-1) of CT-2 for the purpose of recognition of anions in DMSO. The absorption and emission maxima were both determined for the fluorescent dye in different solvents. Both hypsochromic shift at the absorption maximum, and quenching of fluorescence after interactions between the anions and the receptoric part, were observed. This phenomenon was explained using orbital interactions based on quantum chemical calculations. The selectivity and sensitivity of CT-2 for F-, Cl-, Br-, I-, AcO-, CN-, H2PO4-, HSO4- and ClO4- anions were determined with spectrophotometric, fluorimetric and 1H NMR titration techniques and it was found that CT-2 be utilized for the detection of CN-, F- and AcO- in the presence of other ions as competitors. Color and fluorescence changes visible to the naked eye and under UV (365 nm) were observed upon addition of CN-, F- and AcO- to the solution of chemosensor (CT-2) in DMSO. The sensor showed no colorimetric and fluorimetric response for the anions such as Cl-, Br-, I-, H2PO4-, HSO4-, and ClO4-. However, 1H NMR titration shows that the chemosensor was more sensitive to CN-, than F- and AcO- at the stochiometric ratio of 1:2.5 respectively. Additionally, the compounds CT-1 and CT-2 showed good thermal stability for practical applications.
Sk, Mahasin Alam; Chen, Yingqian; Manzhos, Sergei
2016-08-01
We report a qualitative difference in molecular band structures and frontier orbital nodal structures in DFT calculations using GGA vs. hybrid functionals and Hartree Fock in molecules used in electrochemical power sources. This can have a significant effect in applications sensitive to redox potentials and to orbital overlaps (excitations, electron transfer rates) but for which the use of hybrid functionals is impractical, such as solids or interfaces used in electrochemical energy conversion and storage technologies. We show that correct band structures and nodal structures (ordering) of frontier orbitals can be obtained by applying a Hubbard correction to selected atomic states.
Optical nanofibres and neutral atoms
Nieddu, Thomas; Gokhroo, Vandna; Chormaic, Síle Nic
2016-05-01
Optical nanofibres are increasingly being used in cold atom experiments due to their versatility and the clear advantages they have when developing all-fibred systems for quantum technologies. They provide researchers with a method of overcoming the Rayleigh range for achieving high intensities in a focussed beam over a relatively long distance, and can act as a noninvasive tool for probing cold atoms. In this review article, we will briefly introduce the theory of mode propagation in an ultrathin optical fibre and highlight some of the more significant theoretical and experimental progresses to date, including the early work on atom probing, manipulation and trapping, the study of atom-dielectric surface interactions, and the more recent observation of nanofibre-mediated nonlinear optics phenomena in atomic media. The functionality of optical nanofibres in relation to the realisation of atom-photon hybrid quantum systems is also becoming more evident as some of the earlier technical challenges are surpassed and, recently, several schemes to implement optical memories have been proposed. We also discuss some possible directions where this research field may head, in particular, in relation to the use of optical nanofibres that can support higher-order modes with an associated orbital angular momentum.
Yuan, S J; Pehkonen, S O; Ting, Y P; Neoh, K G; Kang, E T
2009-03-01
To improve the biocorrosion resistance of stainless steel (SS) and to confer the bactericidal function on its surface for inhibiting bacterial adhesion and biofilm formation, well-defined inorganic-organic hybrid coatings, consisting of the inner compact titanium oxide multilayers and outer dense poly(vinyl-N-hexylpyridinium) brushes, were successfully developed. Nanostructured titanium oxide multilayer coatings were first built up on the SS substrates via the layer-by-layer sol-gel deposition process. The trichlorosilane coupling agent, containing the alkyl halide atom-transfer-radical polymerization (ATRP) initiator, was subsequently immobilized on the titanium oxide coatings for surface-initiated ATRP of 4-vinylpyridine (4VP). The pyridium nitrogen moieties of the covalently immobilized 4VP polymer, or P(4VP), brushes were quaternized with hexyl bromide to produce a high concentration of quaternary ammonium salt on the SS surfaces. The excellent antibacterial efficiency of the grafted polycations, poly(vinyl-N-pyridinium bromide), was revealed by viable cell counts and atomic force microscopy images of the surface. The effectiveness of the hybrid coatings in corrosion protection was verified by the Tafel plot and electrochemical impedance spectroscopy measurements.
Wang, Kai; Yao, Zhanwei; Li, Runbing; Lu, Sibin; Chen, Xi; Wang, Jin; Zhan, Mingsheng
2016-02-10
We report a hybrid scheme for phase-coherent Raman lasers with low phase noise in a wide frequency range. In this scheme, a pair of Raman lasers with a frequency difference of 3.04 GHz is generated by the ±1-order diffracted lights of an acousto-optic modulator (1.52 GHz), where a feedback loop is simultaneously applied for suppressing the phase noise. The beat width of the Raman lasers is narrower than 3 Hz. In the low-frequency range, the phase noise of the Raman lasers is suppressed by 35 dB with the feedback. The phase noise is less than -109 dBc/Hz in the high-frequency range. The sensitivity of an atom gyroscope employing the hybrid Raman lasers can be implicitly improved 10 times. Due to the better high-frequency response, the sensitivity is not limited by the durations of Raman pulses. This work is important for improving the performance of atom-interferometer-based measurements.
Zhang, Guiqiu; Li, Xiwen; Li, Yan; Chen, Dezhan
2013-11-01
In this report, we extended the works of Rizzato et al. [Angew. Chem. Int. Ed. 49, 7440 (2010)] on the nature of O-H...Pt hydrogen bond in trans-[PtCl2(NH3)(N-glycine)].H2O(1.H2O) complex, by computational study of O-H...Pt interaction in [NBu4][Pt(C6F5)3(8-hydroxyquinaldine)], with emphasis on charge transfer effect in this interaction of platinum(II) and hydrogen atom. According to the crystallographic geometry reported by José María Casas et al., [NBu4][Pt(C6F5)3(8-hydroxyquinaldine)] possesses one O-H...Pt hydrogen bridging interaction, similar to the case in trans-[PtCl2(NH3)(N-glycine)].H2O(1.H2O) complex. On the basis of topological criteria of electron density, we characterised this O-H...Pt interaction. Charge transferred between platinum(II) and σ*O-H orbital in this complex was calculated by using NBO method. The stabilised energy associated to charge transfer was estimated using a direct proportionality, that is 2-3 eV per electron transferred. Charge transfer effects in O-H...Pt hydrogen bonds were studied for these two complexes. Our results indicate that the interaction of O-H...Pt is closed-shell in nature with significant charge transfer, and that charge transfer effect is not negligible in the interaction of O-H...Pt. The second conclusion is different from the result of Rizzato et al.
Ching, Wai-Yim; Rulis, Paul
2009-03-11
Over the last eight years, a large number of x-ray absorption near edge structure (XANES) and/or electron energy loss near edge structure (ELNES) spectroscopic calculations for complex oxides and nitrides have been performed using the supercell-OLCAO (orthogonalized linear combination of atomic orbitals) method, obtaining results in very good agreement with experiments. The method takes into account the core-hole effect and includes the dipole matrix elements calculated from ab initio wavefunctions. In this paper, we describe the method in considerable detail, emphasizing the special advantages of this method for large complex systems. Selected results are reviewed and several hitherto unpublished results are also presented. These include the Y K edge of Y ions segregated to the core of a Σ31 grain boundary in alumina, O K edges of water molecules, C K edges in different types of single walled carbon nanotubes, and the Co K edge in the cyanocobalamin (vitamin B(12)) molecule. On the basis of these results, it is argued that the interpretation of specific features of the calculated XANES/ELNES edges is not simple for complex material systems because of the delocalized nature of the conduction band states. The long-standing notion of the 'fingerprinting' technique for spectral interpretation of experimental data is not tenable. A better approach is to fully characterize the structure under study, using either crystalline data or accurate ab initio modeling. Comparison between calculated XANES/ELNES spectra and available measurements enables us to ascertain the validity of the modeled structure. For complex crystals or structures, it is necessary to use the weighted sum of the spectra from structurally nonequivalent sites for comparison with the measured data. Future application of the supercell-OLCAO method to complex biomolecular systems is also discussed.
Energy Technology Data Exchange (ETDEWEB)
Ching, W.-Y.; Rulis, Paul [Department of Physics, University of Missouri-Kansas City, Kansas City, MO 64110 (United States)
2009-03-11
Over the last eight years, a large number of x-ray absorption near edge structure (XANES) and/or electron energy loss near edge structure (ELNES) spectroscopic calculations for complex oxides and nitrides have been performed using the supercell-OLCAO (orthogonalized linear combination of atomic orbitals) method, obtaining results in very good agreement with experiments. The method takes into account the core-hole effect and includes the dipole matrix elements calculated from ab initio wavefunctions. In this paper, we describe the method in considerable detail, emphasizing the special advantages of this method for large complex systems. Selected results are reviewed and several hitherto unpublished results are also presented. These include the Y K edge of Y ions segregated to the core of a {sigma}31 grain boundary in alumina, O K edges of water molecules, C K edges in different types of single walled carbon nanotubes, and the Co K edge in the cyanocobalamin (vitamin B{sub 12}) molecule. On the basis of these results, it is argued that the interpretation of specific features of the calculated XANES/ELNES edges is not simple for complex material systems because of the delocalized nature of the conduction band states. The long-standing notion of the 'fingerprinting' technique for spectral interpretation of experimental data is not tenable. A better approach is to fully characterize the structure under study, using either crystalline data or accurate ab initio modeling. Comparison between calculated XANES/ELNES spectra and available measurements enables us to ascertain the validity of the modeled structure. For complex crystals or structures, it is necessary to use the weighted sum of the spectra from structurally nonequivalent sites for comparison with the measured data. Future application of the supercell-OLCAO method to complex biomolecular systems is also discussed.
Ching, Wai-Yim; Rulis, Paul
2009-03-01
Over the last eight years, a large number of x-ray absorption near edge structure (XANES) and/or electron energy loss near edge structure (ELNES) spectroscopic calculations for complex oxides and nitrides have been performed using the supercell-OLCAO (orthogonalized linear combination of atomic orbitals) method, obtaining results in very good agreement with experiments. The method takes into account the core-hole effect and includes the dipole matrix elements calculated from ab initio wavefunctions. In this paper, we describe the method in considerable detail, emphasizing the special advantages of this method for large complex systems. Selected results are reviewed and several hitherto unpublished results are also presented. These include the Y K edge of Y ions segregated to the core of a Σ31 grain boundary in alumina, O K edges of water molecules, C K edges in different types of single walled carbon nanotubes, and the Co K edge in the cyanocobalamin (vitamin B12) molecule. On the basis of these results, it is argued that the interpretation of specific features of the calculated XANES/ELNES edges is not simple for complex material systems because of the delocalized nature of the conduction band states. The long-standing notion of the 'fingerprinting' technique for spectral interpretation of experimental data is not tenable. A better approach is to fully characterize the structure under study, using either crystalline data or accurate ab initio modeling. Comparison between calculated XANES/ELNES spectra and available measurements enables us to ascertain the validity of the modeled structure. For complex crystals or structures, it is necessary to use the weighted sum of the spectra from structurally nonequivalent sites for comparison with the measured data. Future application of the supercell-OLCAO method to complex biomolecular systems is also discussed.
Chen, Lei; Chen, Xiuling; Liu, Fayong; Chen, Haohong; Wang, Hui; Zhao, Erlong; Jiang, Yang; Chan, Ting-Shan; Wang, Chia-Hsin; Zhang, Wenhua; Wang, Yu; Chen, Shifu
2015-07-01
The deficiency of Y3Al5O12:Ce (YAG:Ce) luminescence in red component can be compensated by doping Gd3+, thus lead to it being widely used for packaging warm white light-emitting diode devices. This article presents a systematic study on the photoluminescence properties, crystal structures and electronic band structures of (Y1-xGdx)3Al5O12: Ce3+ using powerful experimental techniques of thermally stimulated luminescence, X-ray diffraction, X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS) and ultraviolet photoelectron spectra (UPS) of the valence band, assisted with theoretical calculations on the band structure, density of states (DOS), and charge deformation density (CDD). A new interpretation from the viewpoint of compression deformation of electron cloud in a rigid structure by combining orbital hybridization with solid-state energy band theory together is put forward to illustrate the intrinsic mechanisms that cause the emission spectral shift, thermal quenching, and luminescence intensity decrease of YAG: Ce upon substitution of Y3+ by Gd3+, which are out of the explanation of the classic configuration coordinate model. The results indicate that in a rigid structure, the charge deformation provides an efficient way to tune chromaticity, but the band gaps and crystal defects must be controlled by comprehensively accounting for luminescence thermal stability and efficiency.
Chen, Lei; Chen, Xiuling; Liu, Fayong; Chen, Haohong; Wang, Hui; Zhao, Erlong; Jiang, Yang; Chan, Ting-Shan; Wang, Chia-Hsin; Zhang, Wenhua; Wang, Yu; Chen, Shifu
2015-07-15
The deficiency of Y3Al5O12:Ce (YAG:Ce) luminescence in red component can be compensated by doping Gd(3+), thus lead to it being widely used for packaging warm white light-emitting diode devices. This article presents a systematic study on the photoluminescence properties, crystal structures and electronic band structures of (Y1-xGdx)3Al5O12: Ce(3+) using powerful experimental techniques of thermally stimulated luminescence, X-ray diffraction, X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS) and ultraviolet photoelectron spectra (UPS) of the valence band, assisted with theoretical calculations on the band structure, density of states (DOS), and charge deformation density (CDD). A new interpretation from the viewpoint of compression deformation of electron cloud in a rigid structure by combining orbital hybridization with solid-state energy band theory together is put forward to illustrate the intrinsic mechanisms that cause the emission spectral shift, thermal quenching, and luminescence intensity decrease of YAG: Ce upon substitution of Y(3+) by Gd(3+), which are out of the explanation of the classic configuration coordinate model. The results indicate that in a rigid structure, the charge deformation provides an efficient way to tune chromaticity, but the band gaps and crystal defects must be controlled by comprehensively accounting for luminescence thermal stability and efficiency.
Energy Technology Data Exchange (ETDEWEB)
Wang, Xiao, E-mail: wangxiao@dlpu.edu.cn [School of Textile and Materials Engineering, Dalian Polytechnic University, Dalian, Liaoning Province (China); Zhang, Yue; Lv, Lihua; Cui, Yongzhu; Wei, Chunyan [School of Textile and Materials Engineering, Dalian Polytechnic University, Dalian, Liaoning Province (China); Pang, Guibing [School of Mechanical Engineering and Automation, Dalian Polytechnic University, Dalian, Liaoning Province (China)
2016-02-15
Graphical abstract: - Highlights: • Adsorbed anionic dye molecules are conducive to preferential growth of (0 0 1) plane of Mg(OH){sub 2} crystal for Mg(OH){sub 2} pigments. • Uniform coverage of nanosized Mg(OH){sub 2} pigments on fiber surface is achieved via surface-initiated ATRP. • About 4 wt% of Mg(OH){sub 2} pigment on fiber surface shortens nearly half of burning time of cellulose. - Abstract: Mg(OH){sub 2} flame retardant hybrid pigment is synthesized through simultaneous solution precipitation and adsorption of anionic dyes (C.I. Acid Red 6). The Mg(OH){sub 2} hybrid pigment bearing vinyl groups after surface silane modification is immobilized onto the surface of bromo end-functional cellulose fiber by atom transfer radical polymerization (ATRP). The morphology and structure of Mg(OH){sub 2} pigments and cellulose fibers grafted with modified pigments are characterized. The thermal properties, flammability and color fastness of cellulose fibers grafted with modified pigments are measured. The results reveal that anionic dye molecules are adsorbed onto Mg(OH){sub 2} crystals and affect the formation of lamella-like Mg(OH){sub 2} crystals. The cellulose fiber grafted with modified Mg(OH){sub 2} hybrid pigment absorbs about four times heat more than original cellulose fiber with about 4% immobilization ratio of pigment, which shortens nearly half of afterflame time and afterglow time.
Umemura, Kazuo; Ishizaka, Kei; Nii, Daisuke; Izumi, Katsuki
2016-12-01
Using atomic force spectroscopy (AFM), we observed hybrids of single-stranded DNA (ssDNA) and single-walled carbon nanotubes (SWNTs) with or without protein molecules in air and in an aqueous solution. This is the first report of ssDNA-SWNT hybrids with proteins in solution analyzed by AFM. In the absence of protein, the height of the ssDNA-SWNT hybrids was 1.1 ± 0.3 nm and 2.4 ± 0.6 nm in air and liquid, respectively, suggesting that the ssDNA molecules adopted a flexible structure on the SWNT surface. In the presence of single-stranded DNA binding (SSB) proteins, the heights of the hybrids in air and liquid increased to 6.4 ± 3.1 nm and 10.0 ± 4.5 nm, respectively. The AFM images clearly showed binding of the SSB proteins to the ssDNA-SWNT hybrids. The morphology of the SSB-ssDNA-SWNT hybrids was non-uniform, particularly in aqueous solution. The variance of hybrid height was quantitatively estimated by cross-section analysis along the long-axis of each hybrid. The SSB-ssDNA-SWNT hybrids showed much larger variance than the ssDNA-SWNT hybrids.
Liu, Jingyi; Zhang, Wenzhao; Li, Xun; Yan, Weibin; Zhou, Ling
2016-10-01
We investigate the two-photon transport properties inside one-dimensional waveguide side coupled to an atom-optomechanical system, aiming to control the two-photon transport by using the nonlinearity. By generalizing the scheme of Phys. Rev. A 90, 033832, we show that Kerr nonlinearity induced by the four-level atoms is remarkable and can make the photons antibunching, while the nonlinear interaction of optomechanical coupling participates in both the single photon and the two photon processes so that it can make the two photons exhibiting bunching and antibunching.
Liu, A.-Peng; Cheng, Liu-Yong; Guo, Qi; Zhang, Shou; Zhao, Ming-Xia
2017-01-01
We propose deterministic schemes for controlled-NOT (CNOT), Toffoli, and Fredkin gates between flying photon qubits and the collective spin wave (magnon) of an atomic ensemble inside double-sided optical microcavities. All the gates can be accomplished with 100% success probability in principle and no additional qubit is required. Atomic ensemble is employed so that light-matter coupling is remarkably improved by collective enhancement. We qualified the performance of the gates and the results show that they can be faithfully constituted with current experimental techniques. PMID:28272548
Moore, Brian G.
2000-06-01
The plotting program Gnuplot is freely available, general purpose, easy to use, and available on a variety of platforms. Complex three-dimensional surfaces, including the familiar angular parts of the hydrogen atom orbitals, are easily represented using Gnuplot. Contour plots allow viewing the radial and angular variation of the probability density in an orbital. Examples are given of how Gnuplot is used in an undergraduate physical chemistry class to view familiar atomic orbitals in new ways or to generate views of orbital functions that the student may have not seen before. Gnuplot may also be easily integrated into the environment of a Web page; an example of this is discussed (and is available at http://onsager.bd.psu.edu/~moore/orbitals_gnuplot). The plotting commands are entered with a form and a CGI script is used to run Gnuplot and display the result back to the browser.
梯状光晶格中自旋轨道耦合的排斥费米气体%Spin-orbit coupled Fermi atoms loaded in an optical ladder lattice
Institute of Scientific and Technical Information of China (English)
郭飞翔; 周晓凡; 赵华
2015-01-01
采用密度矩阵重整化群 ( density-matrix-renormalization-group, DMRG) 方法, 研究梯状光晶格中排斥相互作用费米气体的基态属性. 研究表明, Zeeman场能够激发系统的相分离 (完全极化相和部分极化相), 而自旋轨道耦合效应能抑制相分离, 使整个晶格处于部分极化相, 在不同的强弱排斥相互作用系统中, 极化率会随自旋轨道耦合改变表现出不同的变化规律.%The density-matrix-renormalization-group ( DMRG ) method is used to numerically calculate the ground state of repulsively interacting Fermi atoms loaded in optical ladder lattices. It is found that the system exhibits the spatial separation of a fully spin-polarized phase from the partially polarized phase for the suitable intensity of Zeeman field without the effect of spin-orbit coupled atoms. The spin-orbit coupling drives the fully spin-polarized phase to the partially spin-polarized phase in the whole system. The spin polarizations of weak and strong repulsively interac-ting systems vary differently with spin-orbit interaction strength.
Yuan, S J; Pehkonen, S O; Ting, Y P; Neoh, K G; Kang, E T
2010-05-04
To enhance the corrosion resistance of stainless steel (SS) and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, well-defined inorganic-organic hybrid coatings, consisting of a polysilsesquioxane inner layer and quaternized poly(2-(dimethyamino)ethyl methacrylate) (P(DMAEMA)) outer blocks, were prepared via successive surface-initiated atom transfer radical polymerization (ATRP) of 3-(trimethoxysilyl)propyl methacrylate (TMSPMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA). The cross-linked P(TMASPMA), or polysilsesquioxane, inner layer provided a durable and resistant coating to electrolytes. The pendant tertiary amino groups of the P(DMAEMA) outer block were quaternized with alkyl halide to produce a high concentration of quaternary ammonium groups with biocidal functionality. The so-synthesized inorganic-organic hybrid coatings on the SS substrates exhibited good anticorrosion and antibacterial effects and inhibited biocorrosion induced by sulfate-reducing bacteria (SRB) in seawater media, as revealed by antibacterial assay and electrochemical analyses, and they are potentially useful to steel-based equipment under harsh industrial and marine environments.
Li, Shunfang; Zhao, Xingju; Shi, Jinlei; Jia, Yu; Guo, Zhengxiao; Cho, Jun-Hyung; Gao, Yanfei; Zhang, Zhenyu
2016-09-28
Exploration of the catalytic activity of low-dimensional transition metal (TM) or noble metal catalysts is a vital subject of modern materials science because of their instrumental role in numerous industrial applications. Recent experimental advances have demonstrated the utilization of single atoms on different substrates as effective catalysts, which exhibit amazing catalytic properties such as more efficient catalytic performance and higher selectivity in chemical reactions as compared to their nanostructured counterparts; however, the underlying microscopic mechanisms operative in these single atom catalysts still remain elusive. Based on first-principles calculations, herein, we present a comparative study of the key kinetic rate processes involved in CO oxidation using a monomer or dimer of two representative TMs (Pd and Ni) on defective TiO2(110) substrates (TMn@TiO2(110), n = 1, 2) to elucidate the underlying mechanism of single-atom catalysis. We reveal that the O2 activation rates of the single atom TM catalysts deposited on TiO2(110) are governed cooperatively by the classic spin-selection rule and the well-known frontier orbital theory (or generalized d-band picture) that emphasizes the energy gap between the frontier orbitals of the TM catalysts and O2 molecule. We further illuminate that the subsequent CO oxidation reactions proceed via the Langmuir-Hinshelwood mechanism with contrasting reaction barriers for the Pd monomer and dimer catalysts. These findings not only provide an explanation for existing observations of distinctly different catalytic activities of Pd@TiO2(110) and Pd2@TiO2(110) [Kaden et al., Science, 2009, 326, 826-829] but also shed new insights into future utilization and optimization of single-atom catalysis.
Topological orbital superfluid with chiral d-wave order in a rotating optical lattice
Hao, Ningning; Guo, Huaiming; Zhang, Ping
2017-08-01
Topological superfluid is an exotic state of quantum matter that possesses a nodeless superfluid gap in the bulk and Andreev edge modes at the boundary of a finite system. Here, we study a multi-orbital superfluid driven by an attractive s-wave interaction in a rotating optical lattice. Interestingly, we find that the rotation induces the inter-orbital hybridization and drives the system into topological orbital superfluid in accordance with intrinsically chiral d-wave pairing characteristics. Thanks to the conservation of spin, the topological orbital superfluid supports four rather than two chiral Andreev edge modes at the boundary of the lattice. Moreover, we find that the intrinsic harmonic confining potential forms a circular spatial barrier which accumulates atoms and supports a mass current under the injection of small angular momentum as an external driving force. This feature provides an experimentally detectable phenomenon to verify the topological orbital superfluid with chiral d-wave order in a rotating optical lattice.
Chen, Yunjie; Roux, Benoît
2015-08-11
Molecular dynamics (MD) trajectories based on a classical equation of motion provide a straightforward, albeit somewhat inefficient approach, to explore and sample the configurational space of a complex molecular system. While a broad range of techniques can be used to accelerate and enhance the sampling efficiency of classical simulations, only algorithms that are consistent with the Boltzmann equilibrium distribution yield a proper statistical mechanical computational framework. Here, a multiscale hybrid algorithm relying simultaneously on all-atom fine-grained (FG) and coarse-grained (CG) representations of a system is designed to improve sampling efficiency by combining the strength of nonequilibrium molecular dynamics (neMD) and Metropolis Monte Carlo (MC). This CG-guided hybrid neMD-MC algorithm comprises six steps: (1) a FG configuration of an atomic system is dynamically propagated for some period of time using equilibrium MD; (2) the resulting FG configuration is mapped onto a simplified CG model; (3) the CG model is propagated for a brief time interval to yield a new CG configuration; (4) the resulting CG configuration is used as a target to guide the evolution of the FG system; (5) the FG configuration (from step 1) is driven via a nonequilibrium MD (neMD) simulation toward the CG target; (6) the resulting FG configuration at the end of the neMD trajectory is then accepted or rejected according to a Metropolis criterion before returning to step 1. A symmetric two-ends momentum reversal prescription is used for the neMD trajectories of the FG system to guarantee that the CG-guided hybrid neMD-MC algorithm obeys microscopic detailed balance and rigorously yields the equilibrium Boltzmann distribution. The enhanced sampling achieved with the method is illustrated with a model system with hindered diffusion and explicit-solvent peptide simulations. Illustrative tests indicate that the method can yield a speedup of about 80 times for the model system and up
Caledonia, G. E.; Krech, R. H.
1985-01-01
A technique for the generation, in the laboratory, of thermally 'cold', high flux of energetic oxygen atoms is presented. The flux of nearly mono-energetic oxygen atoms is obtained after a laser-induced breakdown of oxygen molecules followed by a rapid expansion of the recombining plasma. The experimental apparatus, the optical and spectral measurements, the O-atom source characterization, and the material degradation studies are discussed. Average oxygen atom velocities of about 5 to 13 km/s are measured with an estimated flux of 10 to the 18th per pulse, over pulse durations of several microseconds. The flow of the O2 gas for about 200 microseconds before applying the laser pulse is found to give best results. It is also found that the energetic O-atom irradiation of sample targets such as Al, Fe, and polyethylene, induces mass removal. In addition, spectral scans of the radiation reveals the existence of two main spectral subsets.
Yi, Di; Liu, Jian; Hsu, Shang-Lin; Zhang, Lipeng; Choi, Yongseong; Kim, Jong-Woo; Chen, Zuhuang; Clarkson, James D; Serrao, Claudy R; Arenholz, Elke; Ryan, Philip J; Xu, Haixuan; Birgeneau, Robert J; Ramesh, Ramamoorthy
2016-06-07
Magnetic anisotropy (MA) is one of the most important material properties for modern spintronic devices. Conventional manipulation of the intrinsic MA, i.e., magnetocrystalline anisotropy (MCA), typically depends upon crystal symmetry. Extrinsic control over the MA is usually achieved by introducing shape anisotropy or exchange bias from another magnetically ordered material. Here we demonstrate a pathway to manipulate MA of 3d transition-metal oxides (TMOs) by digitally inserting nonmagnetic 5d TMOs with pronounced spin-orbit coupling (SOC). High-quality superlattices comprising ferromagnetic La2/3Sr1/3MnO3 (LSMO) and paramagnetic SrIrO3 (SIO) are synthesized with the precise control of thickness at the atomic scale. Magnetic easy-axis reorientation is observed by controlling the dimensionality of SIO, mediated through the emergence of a novel spin-orbit state within the nominally paramagnetic SIO.
Institute of Scientific and Technical Information of China (English)
刘晓辉; 陈默涵; 李鹏飞; 沈瑜; 任新国; 郭光灿; 何力新
2015-01-01
随着超级计算机硬件和数值算法迅速发展,使得目前利用密度泛函理论研究上千个原子体系的电子能带和结构等性质变得可行. 数值原子轨道基组由于其基组较小和局域等特性, 可以很好地与电子结构计算中的线性标度算法等的新算法结合, 用来研究较大尺寸的物理体系. 本文详细介绍了一款中国科学技术大学量子信息重点实验室自主开发的基于数值原子轨道基组的第一性原理计算软件 Atomic-orbital Based Ab-initio Computation at UStc. 大量的测试结果表明: 该软件具有很好的准确性和较高的并行效率, 可以用于包含1000个原子左右的系统的电子结构和原子结构的研究以及分子动力学模拟计算.%With the rapid development of supercomputers and the advances of numerical algorithms, nowadays it is possible to study the electronic, structural and dynamical properties of complicated physical systems containing thousands of atoms using density functional theory (DFT). The numerical atomic orbitals are ideal basis sets for large-scale DFT calculations in terms of their small base size and localized characteristic, and can be mostly easily combined with linear scaling methods. Here we introduce a first-principles simulation package "Atomic-orbital Based Ab-initio Computation at UStc (ABACUS)", developed at the Key Laboratory of Quantum Information, University of Science and Technology of China. This package provides a useful tool to study the electronic, structural and molecular dynamic properties of systems containing up to 1000 atoms. In this paper, we introduce briefly the main algorithms used in the package, including construction of the atomic orbital bases, construction of the Kohn-Sham Hamiltonian in the atomic basis sets, and some details of solving Kohn-Sham equations, including charge mixing, charge extrapolation, smearing etc. We then give some examples calculated using ABACUS: 1) the energy orders
Hoffman, J E; Kim, Z; Wood, A K; Anderson, J R; Dragt, A J; Hafezi, M; Lobb, C J; Orozco, L A; Rolston, S L; Taylor, J M; Vlahacos, C P; Wellstood, F C
2011-01-01
We present a scheme to couple trapped $^{87}$Rb atoms to a superconducting flux qubit through a magnetic dipole transition. We plan to trap atoms on the evanescent wave outside an ultrathin fiber to bring the atoms to less than 10 $\\mu$m above the surface of the superconductor. This hybrid setup lends itself to probing sources of decoherence in superconducting qubits. Our current plan has the intermediate goal of coupling the atoms to a superconducting LC resonator.
... hemolytic streptococci may also cause orbital cellulitis. Orbital cellulitis infections in children may get worse very quickly and ... in the space around the eye. An orbital cellulitis infection can get worse very quickly. A person with ...
Filip, Marina R.; Giustino, Feliciano
2014-01-01
We study the quasiparticle band gap of the hybrid organic-inorganic lead halide perovskite CH$_3$NH$_3$PbI$_3$, using many-body perturbation theory based on the $GW$ approximation. We perform a systematic analysis of the band gap sensitivity to relativistic spin-orbit effects, to the description of semicore Pb-5$d$ and I-4$d$ electrons, and to the starting Kohn-Sham eigenvalues. We find that the inclusion of semicore states increases the calculated band gap by 0.2 eV, and self-consistency on ...
Energy Technology Data Exchange (ETDEWEB)
Chen, Yang, E-mail: cy.jpu@126.com [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Qian, Cheng [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Miao, Naiming [School of Mechanical Engineering, Changzhou University, Changzhou, Jiangsu 213016 (China)
2015-03-31
The positively charged polystyrene (PS) particles with a size of ca. 200 nm were synthesized by soap-free polymerization. The PS cores were coated with silica shells of tunable thickness employing the modified Stöber method. The PS cores were removed by thermal decomposition at 500 °C, resulting in well-defined silica hollow spheres (10–30 nm in shell thickness). The elastic response of the as-synthesized samples was probed by an atomic force microscope (AFM). A point load was applied to the particle surface through a sharp AFM tip, and the force–displacement curves were recorded. Elastic moduli (E) for the PS particles (2.01 ± 0.70 GPa) and the core–shell structured hybrid particles were determined on the basis of Hertzian contact model. The calculated E values of composites exhibited a linear dependence on the silica shell thickness. While the shell thickness increased from ca. 10 to 15 and 20 nm, the E values of composites increased from 4.42 ± 0.27 to 5.88 ± 0.48 and 9.07 ± 0.94 GPa. For core–shell structured organic/inorganic composites, the E values of the hybrid particles were much lower than those of inorganic shells, while these values were much close to those of organic cores. Moreover, the moduli of elasticity of the composites appeared to be determined by the properties of the polymer cores, the species of inorganic shells and the thickness of shells. Besides, the inorganic shells enhanced the mechanical properties of the polymer cores. This work will provide essential experimental and theoretical basis for the design and application of core–shell structured organic/inorganic composite abrasives in chemical mechanical polishing/planarization. - Highlights: • The elastic moduli (E) of the PS/SiO{sub 2} hybrid particles were probed by AFM. • The E values of composites exhibited a linear dependence on the shell thickness. • The elasticity appeared to be determined by the properties of the organic cores. • The E values were affected
Empirical LCAO parameters for \\pi molecular orbitals in planar organic molecules
Hawke, Laurence; Simserides, Constantinos
2008-01-01
We present a simplified LCAO model for the description of \\pi molecular orbitals in organic molecules containing \\pi-bonds between carbon, nitrogen, or oxygen atoms with sp2 hybridization, which we show to be quite accurate in predicting the energy of the highest occupied \\pi orbital and the first \\pi-\\pi* transition energy of a large set of organic compounds. We provide four empirical parameter values for the diagonal matrix elements of the LCAO description, corresponding to atoms of carbon, nitrogen with one pz electron, nitrogen with two pz electrons, and oxygen. The bond-distance dependent formula (proportional to 1/d^2) of Harrison is used for the non-diagonal matrix elements between neighboring atoms. The predictions of our calculations have been tested against available experimental results in more than sixty organic molecules, including benzene and its derivatives, polyacenes, aromatic hydrocarbons of various geometries, polyenes, ketones, aldehydes, azabenzenes, nucleic acids bases and others. The co...
Luo, Jia; Xiang, Gang; Yu, Tian; Lan, Mu; Zhang, Xi
2016-09-01
By using first-principles calculations within the framework of density functional theory, the electronic and magnetic properties of 3d transitional metal (TM) atoms (from Sc to Zn) adsorbed monolayer GaAs nanosheets (GaAsNSs) are systematically investigated. Upon TM atom adsorption, GaAsNS, which is a nonmagnetic semiconductor, can be tuned into a magnetic semiconductor (Sc, V, and Fe adsorption), a half-metal (Mn adsorption), or a metal (Co and Cu adsorption). Our calculations show that the strong p-d hybridization between the 3d orbit of TM atoms and the 4p orbit of neighboring As atoms is responsible for the formation of chemical bonds and the origin of magnetism in the GaAsNSs with Sc, V, and Fe adsorption. However, the Mn 3d orbit with more unpaired electrons hybridizes not only with the As 4p orbit but also with the Ga 4p orbit, resulting in a stronger exchange interaction. Our results may be useful for electronic and magnetic applications of GaAsNS-based materials. Project supported by the National Natural Science Foundation of China (Grant No. 11174212).
An investigation into photofunctional interfaces of 8-hydroxyquinoline/hydroxyapatite hybrids
Tagaya, Motohiro; Motozuka, Satoshi
2017-04-01
Organic/inorganic hybrids of 8-hydroxyquinoline (8Hq) molecule and hydroxyapatite nanocrystal (HAp) were mechanochemically prepared. In the hybrids, a green photoluminescence peak at 500 nm newly appeared, suggesting the chemical bonding of the 8Hq molecule with the Ca2+ ions of HAp. Then, the organic/inorganic interfacial photofunction was clarified by a molecular orbital calculation. The interfacial chemical bonding between the O and N atoms of 8Hq and the Ca2+ ions of HAp was attributed to both covalent Osbnd Ca and ionic Nsbnd Ca. The resultant wave functions revealed that the green luminescence was attributed to metal-to-ligand charge transfer (MLCT) from the O atoms of phosphate group (HAp) to the π-cloud (8Hq) in the HOMO of the hybrids. Therefore, the photofunctional interfaces of the hybrids were successfully demonstrated.
Zhao, Zongyan; Cao, Yuechan; Yi, Juan; He, Xijia; Ma, Chenshuo; Qiu, Jianbei
2012-04-23
As a promising solar-energy material, the electronic structure and optical properties of Beta phase indium sulfide (β-In(2)S(3)) are still not thoroughly understood. This paper devotes to solve these issues using density functional theory calculations. β-In(2)S(3) is found to be an indirect band gap semiconductor. The roles of its atoms at different lattice positions are not exactly identical because of the unique crystal structure. Additonally, a significant phenomenon of optical anisotropy was observed near the absorption edge. Owing to the low coordination numbers of the In3 and S2 atoms, the corresponding In3-5s states and S2-3p states are crucial for the composition of the band-edge electronic structure, leading to special optical properties and excellent optoelectronic performances.
Chaudhuri, Supriya K.; Mukherjee, Prasanta K.; Fricke, Burkhard
2017-03-01
The effect of Debye and quantum plasma environment on the structural properties such as spin orbit splitting, relativistic mass correction and Darwin term for a few iso-electronic members of hydrogen viz. C5 +, O7 +, Ne9 +, Mg11 +, Si13 +, S15 +, Ar17 +, Ca19 + and Ti21 + has been analysed systematically for the first time for a range of coupling strengths of the plasma. The Debye plasma environment has been treated under a standard screened Coulomb potential (SCP) while the quantum plasma has been treated under an exponential cosine screened Coulomb potential (ECSCP). Estimation of the spin orbit splitting under SCP and ECSCP plasma is restricted to the lowest two dipole allowed states while for the other two properties, the ground state as well as the first two excited states have been chosen. Calculations have been extended to nuclear charges for which appreciable relativistic corrections are noted. In all cases calculations have been extended up to such screening parameters for which the respective excitation energies tend towards their stability limit determined by the ionisation potential at that screening parameter. Interesting behavior of the respective properties with respect to the plasma coupling strength has been noted.
Directory of Open Access Journals (Sweden)
Graves N.
2013-01-01
Full Text Available A model is proposed for the hydrogen atom in which the electron is an objectively real particle orbiting at very near to light speed. The model is based on the postulate that certain velocity terms associated with orbiting bodies can be considered as being af- fected by relativity. This leads to a model for the atom in which the stable electron orbits are associated with orbital velocities where Gamma is n /α , leading to the idea that it is Gamma that is quantized and not angular momentum as in the Bohr and other models. The model provides a mechanism which leads to quantization of energy levels within the atom and also provides a simple mechanical explanation for the Fine Struc- ture Constant. The mechanism is closely associated with the Sampling theorem and the related phenomenon of aliasing developed in the mid-20th century by engineers at Bell labs.
Odkhuu, Dorj
2016-08-01
Exploring magnetism and magnetic anisotropy in otherwise nonmagnetic two-dimensional materials, such as graphene and transition metal dichalcogenides, is at the heart of spintronics research. Herein, using first-principles calculations we explore the possibility of reaching an atomic-scale perpendicular magnetic anisotropy by carefully exploring the large spin-orbit coupling, orbital magnetism, and ligand field in a suitable choice of a two-dimensional structure with transition metal adatoms. More specifically, we demonstrate perpendicular magnetic anisotropy energies up to an order of 100 meV per atom in individual ruthenium and osmium adatoms at a monosulfur vacancy in molybdenum disulfide. We further propose a phenomenological model where a spin state transition that involves hybridization between molybdenum a1 and adatomic e' orbitals is a possible mechanism for magnetization reversal from an in-plane to perpendicular orientation.
Jo, Takeo; Imada, Shin
1990-04-01
The Ce 3d- and 4d-core photoabsorption spectra (3d XAS and 4d XAS) of ferromagnetic mixed valent Ce compounds are calculated on the basis of the impurity Anderson model. The model takes into account the Coulomb interaction producing multiplet structures, the spin-orbit interaction, the crystal field effect and the molecular field acting on the 4f spin. The calculation shows a strong circular dichroism even for the Ce magnetic moment of ˜0.5 μB. The dichroism is furthermore shown to be a powerful method to measure the spin and orbital contributions to the 4f moment. On the basis of the calculation, the 4f magnetic state of the ferromagnet CeRh3B2 is discussed.
Loibl, Stefan; Schütz, Martin
2014-07-14
In this paper, we present theory and implementation of an efficient program for calculating magnetizabilities and rotational g tensors of closed-shell molecules at the level of local second-order Møller-Plesset perturbation theory (MP2) using London orbitals. Density fitting is employed to factorize the electron repulsion integrals with ordinary Gaussians as fitting functions. The presented program for the calculation of magnetizabilities and rotational g tensors is based on a previous implementation of NMR shielding tensors reported by S. Loibl and M. Schütz [J. Chem. Phys. 137, 084107 (2012)]. Extensive test calculations show (i) that the errors introduced by density fitting are negligible, and (ii) that the errors of the local approximation are still rather small, although larger than for nuclear magnetic resonance (NMR) shielding tensors. Electron correlation effects for magnetizabilities are tiny for most of the molecules considered here. MP2 appears to overestimate the correlation contribution of magnetizabilities such that it does not constitute an improvement over Hartree-Fock (when comparing to higher-order methods like CCSD(T)). For rotational g tensors the situation is different and MP2 provides a significant improvement in accuracy over Hartree-Fock. The computational performance of the new program was tested for two extended systems, the larger comprising about 2200 basis functions. It turns out that a magnetizability (or rotational g tensor) calculation takes about 1.5 times longer than a corresponding NMR shielding tensor calculation.
(Hybrid) Baryons Symmetries and Masses
Page, P R
1999-01-01
We construct (hybrid) baryons in the flux-tube model of Isgur and Paton. In the limit of adiabatic quark motion, we build proper eigenstates of orbital angular momentum and construct the flavour, spin and J^P of hybrid baryons from the symmetries of the system. The lowest mass hybrid baryon is estimated at approximately 2 GeV.
Interaction of Hg Atom with Bare Si(111) Surface
Institute of Scientific and Technical Information of China (English)
LIU Yong-Jun; LIU Ying
2006-01-01
To evaluate the interaction between Hg atom and bare Si(111) surface, three types of silicon cluster models of Si4H7, Si7H10 and Si16H20 together with their Hg complexes were studied by using hybrid (U)B3LYP density functional theory method. Optimized geometries and energies for Hg atom on different adsorption sites indicate that: 1) the binding energies at different adsorption sites are small (ranging from ～3 to 8 kJ/mol dependent on the adsorption sites), suggesting a weak interaction between Hg atom and silicon surface; 2) the most favorable adsorption site is the on top (T) site. By analyzing their natural bonding orbitals, the possible reason of this difference is suggested.
Hybrid density functional theory LCAO calculations on phonons in Ba (Ti,Zr,Hf) O3
Evaestov, Robert A
2010-01-01
Phonon frequencies at {\\Gamma},X,M,R-points of Brilloin zone in cubic phase of Ba(Ti,Zr,Hf)O3 were first time calculated by frozen phonon method using density functional theory (DFT) with hybrid exchange correlation functional PBE0. The calculations use linear combination of atomic orbitals (LCAO) basis functions as implemented in CRYSTAL09 computer code. The Powell algorithm was applied for basis set optimization. In agreement with the experimental observations the structural instability via...
Importance of local exact exchange potential in hybrid functionals for accurate excited states
Kim, Jaewook; Hwang, Sang-Yeon; Ryu, Seongok; Choi, Sunghwan; Kim, Woo Youn
2016-01-01
Density functional theory has been an essential analysis tool for both theoretical and experimental chemists since accurate hybrid functionals were developed. Here we propose a local hybrid method derived from the optimized effective potential (OEP) method and compare its distinct features with conventional nonlocal ones from the Hartree-Fock (HF) exchange operator. Both are formally exact for ground states and thus show similar accuracy for atomization energies and reaction barrier heights. For excited states, the local version yields virtual orbitals with N-electron character, while those of the nonlocal version have mixed characters between N- and (N+1)-electron orbitals. As a result, the orbital energy gaps from the former well approximate excitation energies with a small mean absolute error (MAE = 0.40 eV) for the Caricato benchmark set. The correction from time-dependent density functional theory with a simple local density approximation kernel further improves its accuracy by incorporating multi-config...
Zhao, Jin; Feng, Min; Yang, Jinlong; Petek, Hrvoje
2009-04-28
Motivated by the discovery of the superatom states of C60 molecules, we investigate the factors that influence their energy and wave function hybridization into nearly free electron bands in molecular solids. As the n = 3 solutions of the radial Schrodinger equation of the central attractive potential consisting of the short-range C atom core and the long-range collective screening potentials, respectively, located on the icosahedral C60 molecule shell and within its hollow core, superatom states are distinguished by their atom-like orbitals corresponding to different orbital angular momentum states (l = 0, 1, 2,...). Because they are less tightly bound than the pi orbitals, that is, the n = 2 states, which are often exploited in the intermolecular electron transport in aromatic organic molecule semiconductors, superatom orbitals hybridize more extensively among aggregated molecules to form bands with nearly free electron dispersion. The prospect of exploiting the strong intermolecular coupling to achieve metal-like conduction in applications such as molecular electronics may be attained by lowering the energy of superatom states from 3.5 eV for single chemisorbed C60 molecules to below the Fermi level; therefore, we study how the superatom state energies depend on factors such as their aggregation into 1D-3D solids, cage size, and exo- and endohedral doping by metal atoms. We find, indeed, that if the ionization potential of endohedral atom, such as copper, is sufficiently large, superatom states can form the conduction band in the middle of the gap between the HOMO and LUMO of the parent C60 molecule. Through a plane-wave density functional theory study, we provide insights for a new paradigm for intermolecular electronic interaction beyond the conventional one among the sp(n) hybridized orbitals of the organic molecular solids that could lead to design of novel molecular materials and quantum structures with extraordinary optical and electronic properties.
Pfefferlé, David; Cooper, Wilfred A
2014-01-01
To identify under what conditions guiding-centre or full-orbit tracing should be used, an estimation of the spatial variation of the magnetic field is proposed, not only taking into account gradient and curvature terms but also the local shear of the field-lines. The criterion is derived for general three-dimensional magnetic equilibria including stellarator plasmas. Details are provided on how to implement it in cylindrical coordinates and in flux coordinates that rely on the geometric toroidal angle. A means of switching between guiding-centre and full-orbit equations at first order in Larmor radius with minimal discrepancy is shown. Techniques are applied to a MAST (Mega Amp Spherical Tokamak) helical core equilibrium in which the inner kinked flux-surfaces are tightly compressed against the outer axisymmetric mantle and where the parallel current peaks at the nearly rational surface. This is put in relation to the simpler situation $\\vec{B}(x,y,z) = B_0 [\\sin(kx) \\vec{e_y} + \\cos(kx)\\vec{e_z}]$, for which...
Energy Technology Data Exchange (ETDEWEB)
Walter, Uwe [University of Rostock, Department of Neurology, Rostock (Germany); Niendorf, Thoralf; Rieger, Jan [Berlin Ultrahigh Field Facility, Max-Delbrueck-Center for Molecular Medicine, Berlin (Germany); MRI.TOOLS GmbH, Berlin (Germany); Graessl, Andreas [Berlin Ultrahigh Field Facility, Max-Delbrueck-Center for Molecular Medicine, Berlin (Germany); Krueger, Paul-Christian; Langner, Soenke [University of Greifswald, Institute for Diagnostic Radiology and Neuroradiology, Greifswald (Germany); Guthoff, Rudolf F.; Stachs, Oliver [University of Rostock, Department of Ophthalmology, Rostock (Germany)
2014-05-15
A combination of magnetic resonance images with real-time high-resolution ultrasound known as fusion imaging may improve ophthalmologic examination. This study was undertaken to evaluate the feasibility of orbital high-field magnetic resonance and real-time colour Doppler ultrasound image fusion and navigation. This case study, performed between April and June 2013, included one healthy man (age, 47 years) and two patients (one woman, 57 years; one man, 67 years) with choroidal melanomas. All cases underwent 7.0-T magnetic resonance imaging using a custom-made ocular imaging surface coil. The Digital Imaging and Communications in Medicine volume data set was then loaded into the ultrasound system for manual registration of the live ultrasound image and fusion imaging examination. Data registration, matching and then volume navigation were feasible in all cases. Fusion imaging provided real-time imaging capabilities and high tissue contrast of choroidal tumour and optic nerve. It also allowed adding a real-time colour Doppler signal on magnetic resonance images for assessment of vasculature of tumour and retrobulbar structures. The combination of orbital high-field magnetic resonance and colour Doppler ultrasound image fusion and navigation is feasible. Multimodal fusion imaging promises to foster assessment and monitoring of choroidal melanoma and optic nerve disorders. (orig.)
Liu, Qihang; Zhang, Xiuwen; Waugh, J. A.; Dessau, D. S.; Zunger, Alex
2016-09-01
Associated with spin-orbit coupling (SOC) and inversion symmetry breaking, Rashba spin polarization opens an avenue for spintronic applications that was previously limited to ordinary magnets. However, spin-polarization effects in actual Rashba systems are far more complicated than what conventional single-orbital models would suggest. By studying via density functional theory and a multiorbital k .p model a three-dimensional bulk Rashba system (free of complications by surface effects), BiTeI, we find that the physical origin of the leading spin-polarization effects is SOC-induced hybridization between spin and multiple orbitals, especially those with nonzero orbital angular momenta. In this framework we establish a general understanding of the orbital mapping, common to the surface of topological insulators and the Rashba system. Consequently, the intrinsic mechanism of various spin-polarization effects—which pertain to all Rashba systems, even those with global inversion symmetry—is understood as a manifestation of the orbital textures. This finding suggests a route for designing high-spin-polarization materials by considering the atomic-orbital content.
Zhang, Jingjing; Luo, Yu; Shen, Xiaopeng; Maier, Stefan A; Cui, Tie Jun
2016-01-01
Plasmon hybridization between closely spaced nanoparticles yields new hybrid modes not found in individual constituents, allowing for the engineering of resonance properties and field enhancement capabilities of metallic nanostructure. Experimental verifications of plasmon hybridization have been thus far mostly limited to optical frequencies, as metals cannot support surface plasmons at longer wavelengths. Here, we introduce the concept of 'spoof plasmon hybridization' in highly conductive metal structures and investigate experimentally the interaction of localized surface plasmon resonances (LSPR) in adjacent metal disks corrugated with subwavelength spiral patterns. We show that the hybridization results in the splitting of spoof plasmon modes into bonding and antibonding resonances analogous to molecular orbital rule and plasmonic hybridization in optical spectrum. These hybrid modes can be manipulated to produce enormous field enhancements (larger than 5000) by tuning the separation between disks or alte...
Donval, Gaël; Moreau, Philippe; Danet, Julien; Larbi, Séverine Jouanneau-Si; Bayle-Guillemaud, Pascale; Boucher, Florent
2017-01-04
Most of the recent developments in EELS modelling has been focused on getting a better agreement with measurements. Less work however has been dedicated to bringing EELS calculations to larger structures that can more realistically describe actual systems. The purpose of this paper is to present a hybrid approach well adapted to calculating the whole set of localised EELS core-loss edges (at the XAS level of theory) on larger systems using only standard tools, namely the WIEN2k and VASP codes. We illustrate the usefulness of this method by applying it to a set of amorphous silicon structures in order to explain the flattening of the silicon L2,3 EELS edge peak at the onset. We show that the peak flattening is actually caused by the collective contribution of each of the atoms to the average spectrum, as opposed to a flattening occurring on each individual spectrum. This method allowed us to reduce the execution time by a factor of 3 compared to a usual-carefully optimised-WIEN2k calculation. It provided even greater speed-ups on more complex systems (interfaces, ∼300 atoms) that will be presented in a future paper. This method is suited to calculate all the localized edges of all the atoms of a structure in a single calculation for light atoms as long as the core-hole effects can be neglected.
Yasir, Kashif Ammar; Zhuang, Lin; Liu, Wu-Ming
2017-01-01
We report a spin-orbit-coupling-induced backaction cooling in an optomechanical system, composed of a spin-orbit-coupled Bose-Einstein condensate trapped in an optical cavity with one movable end mirror, by suppressing heating effects of quantum noises. The collective density excitations of the spin-orbit-coupling-mediated hyperfine states—serving as atomic oscillators equally coupled to the cavity field—trigger strongly driven atomic backaction. We find that the backaction not only revamps low-temperature dynamics of its own but also provides an opportunity to cool the mechanical mirror to its quantum-mechanical ground state. Further, we demonstrate that the strength of spin-orbit coupling also superintends dynamic structure factor and squeezes nonlinear quantum noises, like thermomechanical and photon shot noise, which enhances optomechanical features of the hybrid cavity beyond previous investigations. Our findings are testable in a realistic setup and enhance the functionality of cavity optomechanics with spin-orbit-coupled hyperfine states in the field of quantum optics and quantum computation.
Maeda, Satoshi; Fujita, Masato; Idota, Naokazu; Matsukawa, Kimihiro; Sugahara, Yoshiyuki
2016-12-21
Transparent TiO2/PMMA hybrids with a thickness of 5 mm and improved refractive indices were prepared by in situ polymerization of methyl methacrylate (MMA) in the presence of TiO2 nanoparticles bearing poly(methyl methacrylate) (PMMA) chains grown using surface-initiated atom transfer radical polymerization (SI-ATRP), and the effect of the chain length of modified PMMA on the dispersibility of modified TiO2 nanoparticles in the bulk hybrids was investigated. The surfaces of TiO2 nanoparticles were modified with both m-(chloromethyl)phenylmethanoyloxymethylphosphonic acid bearing a terminal ATRP initiator and isodecyl phosphate with a high affinity for common organic solvents, leading to sufficient dispersibility of the surface-modified particles in toluene. Subsequently, SI-ATRP of MMA was achieved from the modified surfaces of the TiO2 nanoparticles without aggregation of the nanoparticles in toluene. The molecular weights of the PMMA chains cleaved from the modified TiO2 nanoparticles increased with increases in the prolonging of the polymerization period, and these exhibited a narrow distribution, indicating chain growth controlled by SI-ATRP. The nanoparticles bearing PMMA chains were well-dispersed in MMA regardless of the polymerization period. Bulk PMMA hybrids containing modified TiO2 nanoparticles with a thickness of 5 mm were prepared by in situ polymerization of the MMA dispersion. The transparency of the hybrids depended significantly on the chain length of the modified PMMA on the nanoparticles, because the modified PMMA of low molecular weight induced aggregation of the TiO2 nanoparticles during the in situ polymerization process. The refractive indices of the bulk hybrids could be controlled by adjusting the TiO2 content and could be increased up to 1.566 for 6.3 vol % TiO2 content (1.492 for pristine PMMA).
Institute of Scientific and Technical Information of China (English)
王俊; 高先龙
2015-01-01
It was investigated the properties of spin-orbit coupled atomic fermi gases under a Zeeman field. By solving the Bogoliubove-de Gennes equation self-consistently, it was found that the system supported the topol-ogical superfluid state and the Fulde-Ferrell-Larkin-Ovchinnikov superfluid state respectively when the system under the different strength of Zeeman field and filling factors. When the system turned into topological super-fluid state, a pair of zero-energy Majorana fermions were found.%研究了具有自旋轨道耦合的冷原子费米气在外磁场作用下的物理性质。通过自洽求解Bogoliubove-de Gennes方程，发现了在不同磁场强度和粒子填充数下，体系分别存在拓扑超流态和 Fulde-Ferrell-Larkin-Ovchinnikov超流态。当体系处于拓扑超流态时，存在零能Majorana费米子。
Hamaya, S.; Maeda, H.; Funaki, M.; Fukui, H.
2008-12-01
The relativistic calculation of nuclear magnetic shielding tensors in hydrogen halides is performed using the second-order regular approximation to the normalized elimination of the small component (SORA-NESC) method with the inclusion of the perturbation terms from the metric operator. This computational scheme is denoted as SORA-Met. The SORA-Met calculation yields anisotropies, Δσ =σ∥-σ⊥, for the halogen nuclei in hydrogen halides that are too small. In the NESC theory, the small component of the spinor is combined to the large component via the operator σ⃗ṡπ⃗U/2c, in which π⃗=p⃗+A⃗, U is a nonunitary transformation operator, and c ≅137.036 a.u. is the velocity of light. The operator U depends on the vector potential A⃗ (i.e., the magnetic perturbations in the system) with the leading order c-2 and the magnetic perturbation terms of U contribute to the Hamiltonian and metric operators of the system in the leading order c-4. It is shown that the small Δσ for halogen nuclei found in our previous studies is related to the neglect of the U(0,1) perturbation operator of U, which is independent of the external magnetic field and of the first order with respect to the nuclear magnetic dipole moment. Introduction of gauge-including atomic orbitals and a finite-size nuclear model is also discussed.
Study of Magnesium Diboride Clusters Using Hybrid Density Functional Theory
Directory of Open Access Journals (Sweden)
D. Rodríguez
2007-12-01
Full Text Available Using hybrid density functional theory and a relatively large basis set, the lowest energy equilibrium structure, vibrational spectrum, and natural orbital analysis were obtained for magnesium diboride clusters [(MgB2x for x=1,2, and 3]. For comparison, boron clusters [BxÃ‚Â forÃ‚Â x=2,4,Ã‚Â andÃ‚Â 6] were also considered. The MgB2 and (MgB22 showed equilibrium structures with the boron atoms in arrangements similar to what was obtained for pure boron atoms, whereas, for (MgB23 a different arrangement of boron was obtained. From the population analysis, large electron density in the boron atoms forming the clusters was observed.
Hydrogenoid orbitals revisited: From Slater orbitals to Coulomb Sturmians
Indian Academy of Sciences (India)
Danilo Calderini; Simonetta Cavalli; Cecilia Coletti; Gaia Grossi; Vincenzo Qquilanti
2012-01-01
The simple connection between the Slater orbitals, venerable in quantum chemistry, and the Coulomb Sturmian orbitals, more recently employed in atomic and molecular physics, is pointed out explicitly in view of the renewed interest in both as basis sets in applied quantum mechanics. Research in Slater orbitals mainly concerns multicentre, many-body integrals, whereas that on Sturmians exploits their orthonormality and completeness with no need of continuum states. An account of recent progress is outlined, also with reference to relationships between the two basis sets, and with the momentum space and hyperspherical harmonics representations.
Montalbán, A.; Velasco, V. R.; Tutor, J.; Fernández-Velicia, F. J.
2007-06-01
We have studied the vibrational frequencies and atom displacements of one-dimensional systems formed by combinations of Thue-Morse and Rudin-Shapiro quasi-regular stackings with periodic ones. The materials are described by nearest-neighbor force constants and the corresponding atom masses. These systems exhibit differences in the frequency spectrum as compared to the original simple quasi-regular generations and periodic structures. The most important feature is the presence of separate confinement of the atom displacements in one of the parts forming the total composite structure for different frequency ranges, thus acting as a kind of phononic cavity.
Lu, Xiangwen; Gao, Wenpei; Zuo, Jian-Min; Yuan, Jiabin
2015-02-01
Advances in diffraction and transmission electron microscopy (TEM) have greatly improved the prospect of three-dimensional (3D) structure reconstruction from two-dimensional (2D) images or diffraction patterns recorded in a tilt series at atomic resolution. Here, we report a new graphics processing unit (GPU) accelerated iterative transformation algorithm (ITA) based on polar fast Fourier transform for reconstructing 3D structure from 2D diffraction patterns. The algorithm also applies to image tilt series by calculating diffraction patterns from the recorded images using the projection-slice theorem. A gold icosahedral nanoparticle of 309 atoms is used as the model to test the feasibility, performance and robustness of the developed algorithm using simulations. Atomic resolution in 3D is achieved for the 309 atoms Au nanoparticle using 75 diffraction patterns covering 150° rotation. The capability demonstrated here provides an opportunity to uncover the 3D structure of small objects of nanometers in size by electron diffraction.
... Goodlick TA, Kay MD, Glaser JS, Tse DT, Chang WJ. Orbital disease and neuro-ophthalmology. In: Tasman ... 423. Review Date 8/20/2016 Updated by: Franklin W. Lusby, MD, ophthalmologist, Lusby Vision Institute, La ...
DEFF Research Database (Denmark)
Yazdanfard, Younes; Heegard, Steffen; Fledelius, Hans C.
2001-01-01
Ophthalmology, penetrating orbital injury, orbital foreign body, ultrasound, computed tomography (CT), histology......Ophthalmology, penetrating orbital injury, orbital foreign body, ultrasound, computed tomography (CT), histology...
D., I. Bilc; R., Orlando; R., Shaltaf; G., M. Rignanese; J., Íñiguez; Ph., Ghosez
2008-01-01
Using a linear combination of atomic orbitals approach, we report a systematic comparison of various Density Functional Theory (DFT) and hybrid exchange-correlation functionals for the prediction of the electronic and structural properties of prototypical ferroelectric oxides. It is found that none of the available functionals is able to provide, at the same time, accurate electronic and structural properties of the cubic and tetragonal phases of BaTiO$_3$ and PbTiO$_3$. Some, although not al...
First-principles study of palladium atom adsorption on the boron- or nitrogen-doped carbon nanotubes
Energy Technology Data Exchange (ETDEWEB)
Chen Guoxiang [College of Physics and Information Technology, Shaanxi Normal University, Xi' an 710062, Shaanxi (China); School of Science, Xi' an Shiyou University, Xi' an 710065, Shaanxi (China); Zhang Jianmin, E-mail: jianm_zhang@yahoo.co [College of Physics and Information Technology, Shaanxi Normal University, Xi' an 710062, Shaanxi (China); Wang Doudou [Institute of Telecommunication Engineering of the Air Force Engineering University (AFEU1), Xi' an 710077, Shaanxi (China); Xu Kewei [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China)
2009-11-15
We have performed first-principles calculation to investigate the adsorption of a single palladium atom on the surface of the pristine and boron- or nitrogen-doped carbon nanotubes (CNTs). The results show that for the adsorption of a single palladium atom on the pristine CNT surface, the most stable site is Bridge1 site above the axial carbon-carbon bond. Either boron- or nitrogen-doped CNTs can assist palladium surface adsorption, but the detailed mechanisms are different. The enhanced palladium adsorption on boron-doped CNT is attributed to the palladium d orbital strongly hybridized with both boron p orbital and carbon p orbital. The enhancement in palladium adsorption on nitrogen-doped CNT results from activating the nitrogen-neighboring carbon atoms due to the large electron affinity of nitrogen. Furthermore, the axial bond is preferred over the zigzag bond for a palladium atom adsorbed on the surface of all three types of CNTs. The most energetically favorable site for a palladium atom adsorbed on three types of CNTs is above the axial boron-carbon bond in boron-doped CNT. The enhancement in palladium adsorption is more significant for the boron-doped CNT than it is for nitrogen-doped CNT with a similar configuration. So we conclude that accordingly, the preferred adsorption site is determined by the competition between the electron affinity of doped and adsorbed atoms and preferred degree of the axial bond over the zigzag bond.
Energy Technology Data Exchange (ETDEWEB)
Wen, Xiaodong; Martin, Richard L.; Roy, Lindsay E.; Scuseria, Gustavo E.; Rudin, Sven P.; Batista, Enrique R.; McCleskey, Thomas M.; Scott, Brian L.; Bauer, Eve; Joyce, John J.; Durakiewicz, Tomasz
2012-10-21
We present a systematic comparison of the lattice structures, electronic density of states, and band gaps of actinide dioxides, AnO₂ (An=Th, Pa, U, Np, Pu, and Am) predicted by the Heyd-Scuseria-Ernzerhof screened hybrid density functional (HSE) with the self-consistent inclusion of spin-orbit coupling(SOC). The computed HSE lattice constants and band gaps of AnO₂ are in consistently good agreement with the available experimental data across the series, and differ little from earlier HSE results without SOC. ThO₂ is a simple band insulator (f⁰), while PaO₂, UO₂, and NpO₂ are predicted to be Mott insulators. The remainders (PuO₂ and AmO₂) show considerable O2p/An5f mixing and are classified as charge-transfer insulators. We also compare our results for UO₂, NpO₂, and PuO₂with the PBE+U, self interaction correction (SIC), and dynamic mean-field theory (DMFT) many-body approximations.
Wen, Xiao-Dong; Martin, Richard L.; Roy, Lindsay E.; Scuseria, Gustavo E.; Rudin, Sven P.; Batista, Enrique R.; McCleskey, Thomas M.; Scott, Brian L.; Bauer, Eve; Joyce, John J.; Durakiewicz, Tomasz
2012-10-01
We present a systematic comparison of the lattice structures, electronic density of states, and band gaps of actinide dioxides, AnO2 (An=Th, Pa, U, Np, Pu, and Am) predicted by the Heyd-Scuseria-Ernzerhof screened hybrid density functional (HSE) with the self-consistent inclusion of spin-orbit coupling (SOC). The computed HSE lattice constants and band gaps of AnO2 are in consistently good agreement with the available experimental data across the series, and differ little from earlier HSE results without SOC. ThO2 is a simple band insulator (f 0), while PaO2, UO2, and NpO2 are predicted to be Mott insulators. The remainders (PuO2 and AmO2) show considerable O2p/An5f mixing and are classified as charge-transfer insulators. We also compare our results for UO2, NpO2, and PuO2 with the PBE+U, self interaction correction (SIC), and dynamic mean-field theory (DMFT) many-body approximations.
Energy Technology Data Exchange (ETDEWEB)
Kido, Kentaro, E-mail: kido.kentaro@jaea.go.jp [Nuclear Safety Research Center, Japan Atomic Energy Agency, 2-4 Shirane, Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Kasahara, Kento [Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); Yokogawa, Daisuke [Department of Chemistry, Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602 (Japan); Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya 464-8062 (Japan); Sato, Hirofumi [Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); Elements Strategy Institute for Catalysts and Batteries (ESICB), Kyoto University, Katsura, Kyoto 615-8520 (Japan)
2015-07-07
In this study, we reported the development of a new quantum mechanics/molecular mechanics (QM/MM)-type framework to describe chemical processes in solution by combining standard molecular-orbital calculations with a three-dimensional formalism of integral equation theory for molecular liquids (multi-center molecular Ornstein–Zernike (MC-MOZ) method). The theoretical procedure is very similar to the 3D-reference interaction site model self-consistent field (RISM-SCF) approach. Since the MC-MOZ method is highly parallelized for computation, the present approach has the potential to be one of the most efficient procedures to treat chemical processes in solution. Benchmark tests to check the validity of this approach were performed for two solute (solute water and formaldehyde) systems and a simple S{sub N}2 reaction (Cl{sup −} + CH{sub 3}Cl → ClCH{sub 3} + Cl{sup −}) in aqueous solution. The results for solute molecular properties and solvation structures obtained by the present approach were in reasonable agreement with those obtained by other hybrid frameworks and experiments. In particular, the results of the proposed approach are in excellent agreements with those of 3D-RISM-SCF.
A Quantum Model of Atoms (the Energy Levels of Atoms).
Rafie, Francois
2001-01-01
Discusses the model for all atoms which was developed on the same basis as Bohr's model for the hydrogen atom. Calculates the radii and the energies of the orbits. Demonstrates how the model obeys the de Broglie's hypothesis that the moving electron exhibits both wave and particle properties. (Author/ASK)
Gangadharan, Rubarani P; Krishnan, S Sampath
2015-06-01
The molecular structure of cyclohexanone was calculated by the B3LYP density functional model with 6-31G(d, p) and 6-311++G(d,p) basis set by Gaussian program. The results from natural bond orbital (NBO) analysis have been analyzed in terms of the hybridization of atoms and the electronic structure of the title molecule. The electron density based local reactivity descriptors such as Fukui functions were calculated. The dipole moment (μ) and polarizability (a), anisotropy polarizability (Δα) and first order hyperpolarizability (β(tot)) of the molecule have been reported. Thermodynamic properties of the title compound were calculated at different temperatures.
Institute of Scientific and Technical Information of China (English)
Rubarani P Gangadharan; S Sampat H Krishnan
2015-01-01
The molecular structure of cyclohexanone was calculated by the B3LYP density functional model with 6‐31G(d ,p) and 6‐311+ +G(d ,p) basis set by Gaussian program .The results from natural bond orbital (NBO) analysis have been analyzed in terms of the hybridization of atoms and the electronic structure of the ti‐tle molecule .The electron density based local reactivity descriptors such as Fukui functions were calculated . The dipole moment (μ) and polarizability (α) ,anisotropy polarizability (Δα) and first order hyperpolarizability (βtot ) of the molecule have been reported .Thermodynamic properties of the title compound were calculated at different temperatures .
The Relativistic Effects on the Carbon-Carbon Coupling Constants Mediated by a Heavy Atom.
Wodyński, Artur; Malkina, Olga L; Pecul, Magdalena
2016-07-21
The (2)JCC, (3)JCC, and (4)JCC spin-spin coupling constants in the systems with a heavy atom (Cd, In, Sn, Sb, Te, Hg, Tl, Pb, Bi, and Po) in the coupling path have been calculated by means of density functional theory. The main goal was to estimate the relativistic effects on spin-spin coupling constants and to explore the factors which may influence them, including the nature of the heavy atom and carbon hybridization. The methods applied range, in order of reduced complexity, from the Dirac-Kohn-Sham (DKS) method (density functional theory with four-component Dirac-Coulomb Hamiltonian), through DFT with two- and one-component zeroth-order regular approximation (ZORA) Hamiltonians, to scalar effective core potentials (ECPs) with the nonrelativistic Hamiltonian. The use of DKS and ZORA methods leads to very similar results, and small-core ECPs of the MDF and MWB variety reproduce correctly the scalar relativistic effects. Scalar relativistic effects usually are larger than the spin-orbit coupling effects. The latter tend to influence the most the coupling constants of the sp(3)-hybridized carbon atoms and in compounds of the p-block heavy atoms. Large spin-orbit coupling contributions for the Po compounds are probably connected with the inverse of the lowest triplet excitation energy.
Chen, Qing-Yuan; Liu, Ming-Yang; Huang, Yang; Cao, Chao; He, Yao
2017-04-01
The inorganic-organic perovskite CH3NH3PbI3 is a hot research material owing to its outstanding performances as one light absorbing layer of solid-state dye-sensitized solar cells. In this study, we focused on the atomic size effect on CH3NH3BI3 (B = Sn, Pb), provided the best atomic size with which CH3NH3BI3 absorbs widest range of different wavelengths of light, by first-principles calculation. We found that the halogen I-p states are mainly composed of the valence band maximum (VBM) of CH3NH3BI3, and the cation B-p states are primarily composed of the conduction band minimum (CBM). Besides, the bandgap of CH3NH3BI3 decreases and absorptive capacities of different wavelengths of light expand when we reduced the size of the atom and changed B atom from Pb to Sn during the change of suitable range. From all of the above, it is discovered that when the atomic size is 20% less than the normal size, CH3NH3PbI3 has the best optical properties, and its light-absorption range is the widest among all sizes of CH3NH3BI3 compounds. All these results reveal that the stress and strain on CH3NH3BI3 change the atomic size which leads to alteration of bandgap and optical properties in high-efficiency solar cells among all CH3NH3BI3 compounds, namely we can enhance the efficiency of the inorganic-organic perovskite solar cells by setting up suitable pressure on the material in future.
Tsekov, R
2014-01-01
The finite size effect of electron and nucleus is accounted for in the model of atom. Due to their hard sphere repulsion the energy of the 1s orbital decreases and the corrections amount up to 8 % in Uranium. Several models for boundary conditions on the atomic nucleus surface are discussed as well.
Optical angular momentum and atoms.
Franke-Arnold, Sonja
2017-02-28
Any coherent interaction of light and atoms needs to conserve energy, linear momentum and angular momentum. What happens to an atom's angular momentum if it encounters light that carries orbital angular momentum (OAM)? This is a particularly intriguing question as the angular momentum of atoms is quantized, incorporating the intrinsic spin angular momentum of the individual electrons as well as the OAM associated with their spatial distribution. In addition, a mechanical angular momentum can arise from the rotation of the entire atom, which for very cold atoms is also quantized. Atoms therefore allow us to probe and access the quantum properties of light's OAM, aiding our fundamental understanding of light-matter interactions, and moreover, allowing us to construct OAM-based applications, including quantum memories, frequency converters for shaped light and OAM-based sensors.This article is part of the themed issue 'Optical orbital angular momentum'. © 2017 The Author(s).
Diffractive molecular-orbital tomography
Zhai, Chunyang; Zhu, Xiaosong; Lan, Pengfei; Wang, Feng; He, Lixin; Shi, Wenjing; Li, Yang; Li, Min; Zhang, Qingbin; Lu, Peixiang
2017-03-01
High-order-harmonic generation in the interaction of femtosecond lasers with atoms and molecules opens the path to molecular-orbital tomography and to probe the electronic dynamics with attosecond-Ångström resolutions. Molecular-orbital tomography requires both the amplitude and phase of the high-order harmonics. Yet the measurement of phases requires sophisticated techniques and represents formidable challenges at present. Here we report a scheme, called diffractive molecular-orbital tomography, to retrieve the molecular orbital solely from the amplitude of high-order harmonics without measuring any phase information. We have applied this method to image the molecular orbitals of N2, CO2, and C2H2 . The retrieved orbital is further improved by taking account the correction of Coulomb potential. The diffractive molecular-orbital tomography scheme, removing the roadblock of phase measurement, significantly simplifies the molecular-orbital tomography procedure and paves an efficient and robust way to the imaging of more complex molecules.
Oxygen Atom Adsorption on and Diffusion into Nb(110) and Nb(100) from First Principles
Energy Technology Data Exchange (ETDEWEB)
Tafen, De Nyago; Gao, Michael C
2013-11-01
In order to understand the dynamics of oxidation of Nb, we examine the adsorption, absorption, and diffusion of an oxygen atom on, in, and into Nb(110) and Nb(100) surfaces, respectively, using density functional theory. Our calculations predict that the oxygen atom adsorbs on the threefold site on Nb(110) and the fourfold hollow site on Nb(100), and the adsorption energy is -5.08 and -5.18 eV respectively. We find the long and short bridge sites to be transition states for O diffusion on Nb(110), while the on top site is a rank-2 saddle point. In the subsurface region, the oxygen atom prefers the octahedral site, as in bulk niobium. Our results also show that the O atom is more stable on Nb(110) subsurface than on Nb(100) subsurface. The diffusion of oxygen atoms into niobium surfaces passes through transition states where the oxygen atom is coordinated to four niobium atoms. The diffusion barriers of the oxygen atom into Nb(110) and Nb(100) are 1.81 and 2.05 eV, respectively. Analysis of the electronic density of states reveals the emergence of well localized electronic states below the lowest states of clean Nb surfaces due to d-p orbital hybridization.
Oxygen Atom Adsorption on and Diffusion into Nb(110) and Nb(100) from First Principles
Energy Technology Data Exchange (ETDEWEB)
Tafen, De Nyago; Gao, Michael C
2013-11-01
In order to understand the dynamics of oxidation of Nb, we examine the adsorption, absorption, and diffusion of an oxygen atom on, in, and into Nb(110) and Nb(100) surfaces, respectively, using density functional theory. Our calculations predict that the oxygen atom adsorbs on the threefold site on Nb(110) and the fourfold hollow site on Nb(100), and the adsorption energy is -5.08 and -5.18 eV respectively. We find the long and short bridge sites to be transition states for O diffusion on Nb(110), while the on top site is a rank-2 saddle point. In the subsurface region, the oxygen atom prefers the octahedral site, as in bulk niobium. Our results also show that the O atom is more stable on Nb(110) subsurface than on Nb(100) subsurface. The diffusion of oxygen atoms into niobium surfaces passes through transition states where the oxygen atom is coordinated to four niobium atoms. The diffusion barriers of the oxygen atom into Nb(110) and Nb(100) are 1.81 and 2.05 eV, respectively. Analysis of the electronic density of states reveals the emergence of well localized electronic states below the lowest states of clean Nb surfaces due to d-p orbital hybridization.
Murphy, Andrew; Haestad, Jace; Morgan, Thomas
2015-09-01
We report characteristics of closed classical orbits in an electric field in phase space produced in photoabsorption. Rydberg states of atomic and molecular hydrogen and helium are considered. The core potential used for the hydrogen molecule is an effective one electron one center core potential evaluated at the internuclear equilibrium distance. Poincare surfaces of section in phase space are generated by integrating the equations of motion in semiparabolic coordinates u = (r + z) 1 / 2 and v = (r - z) 1 / 2, and plotting the location in phase space (pv versus v) whenever u = 0, with the electric field in the z direction. Combination orbits produced by Rydberg electron core scattering are studied and the evolution in phase space of these combination orbits due to scattering from one closed orbit into another is investigated. Connections are made to measured laser photoabsorption experiments that excite Rydberg states (20 recurrence spectra. The phase space structures responsible for the spectra are identified.
Energy Technology Data Exchange (ETDEWEB)
Moriya, Maki; Miyahara, Masahiko; Hokazono, Mana; Sasaki, Hirokazu; Nemoto, Atsushi; Katayama, Shingo; Akimoto, Yuji; Hirano, Shin-ichi; Ren, Yang
2014-10-01
The stable cycling performance with a high discharge capacity of similar to 190 mAh g(-1) in a carbon-hybridized Li2MnSiO4 nanostructured powder has prompted an experimental investigation of the charged/discharged structures using synchrotron-based and laboratory-based X-rays and atomic-pair distributionfunction (PDF) analyses. A novel method of in-situ spray pyrolysis of a precursor solution with glucose as a carbon source enabled the successful synthesis of the carbon-hybridized Li2(M)nSiO(4) nanoparticles. The XRD patters of the discharged (lithiated) samples exhibit a long-range ordered structure characteristic of the (beta) Li2MnSiO4 crystalline phase (space group Pmn2(1)) which dissipates in the charged (delithiated) samples. However, upon discharging the long-range ordered structure recovers in each cycle. The disordered structure, according to the PDF analysis, is mainly due to local distortions of the MnO4 tetrahedra which show a mean Mn-O nearest neighbor distance shorter than that of the long-range ordered phase. These results corroborate the notion of the smaller Mn3+/Mn4+ ionic radii in the Li extracted phase versus the larger Mn2+ ionic radius in Li inserted phase. Thus Li extraction/insertion drives the fluctuation between the disordered and the long-range ordered structures. (C) 2014 Elsevier B.V. All rights reserved.
Recolliding orbits in an intense laser field
Kamor, Adam; Chandre, Cristel; UZer, Turgay
2013-01-01
We show that a family of key periodic orbits drive the recollision process in a strong circulary polarized laser field. These orbits, coined recolliding periodic orbits, exist for a wide range of parameters and their relative influence changes as the laser and atomic parameters are varied. We find the necessary conditions for recollision-driven nonsequential double ionization to occur. The outlined mechanism is universal in that it applies equally well beyond atoms: The internal structure of the target species plays a minor role in the recollision process.
Geometric orbit datum and orbit covers
Institute of Scientific and Technical Information of China (English)
梁科; 侯自新
2001-01-01
Vogan conjectured that the parabolic induction of orbit data is independent of the choice of the parabolic subgroup. In this paper we first give the parabolic induction of orbit covers, whose relationship with geometric orbit datum is also induced. Hence we show a geometric interpretation of orbit data and finally prove the conjugation for geometric orbit datum using geometric method.
Thermal transport in novel carbon allotropes with s p2 or s p3 hybridization: An ab initio study
Yue, Sheng-Ying; Qin, Guangzhao; Zhang, Xiaoliang; Sheng, Xianlei; Su, Gang; Hu, Ming
2017-02-01
Thermal transport in most carbon allotropes is determined by phonons. The properties of the atomic bonds will influence the phonon transport process directly. In this paper we studied two novel carbon allotropes as examples, one novel allotrope phase is topological semimetal in an s p2 bonding network with a 16-atom body-centered orthorhombic unit cell (BCO-C16) [Phys. Rev. Lett. 116, 195501 (2016), 10.1103/PhysRevLett.116.195501] and the other novel allotrope is derived by substituting each atom in diamond with a carbon tetrahedron (T-carbon) [Phys. Rev. Lett. 106, 155703 (2011), 10.1103/PhysRevLett.106.155703], which possesses an s p3 bonding network. Graphene and diamond with standard s p2 and s p3 hybridization, respectively, are also examined for comparison. We explored the related properties of the atomic bonds of these allotropes with the density functional theory, i.e., the atomic orbital hybridization, effective spring constants of atomic bonds, the anharmonicity of atomic bonds, etc. By comparing the results, we unveiled the veil behind different lattice thermal conductivities of these allotropes at atomic bond levels (BCO-C16 vs graphene and T-carbon vs diamond), despite their similar hybridization. In addition, within the framework of a phonon Boltzmann transport equation, the mode level phonon transport properties of the four carbon allotropes are also studied in detail, which are well consistent with the information from atomic bonds. We expect that the method of analyzing the strength and anharmonicity of atomic bonds here will be helpful for studying the thermal transport in crystalline materials in the future.
Energy Technology Data Exchange (ETDEWEB)
Teixeira Tarley, Cesar Ricardo, E-mail: tarley@uel.br [Programa de Pos-Graduacao em Quimica da Universidade Federal de Alfenas, Rua Gabriel Monteiro da Silva 700, Alfenas, MG, CEP 37130-000 (Brazil); Instituto Nacional de Ciencia e Tecnologia (INCT) de Bioanalitica, Universidade Estadual de Campinas (UNICAMP), Instituto de Quimica, Departamento de Quimica Analitica, Cidade Universitaria Zeferino Vaz s/n, Campinas, SP, CEP 13083-970 (Brazil); Departamento de Quimica, Universidade Estadual de Londrina, Rod. Celso Garcia Cid, PR 445 Km 380, Campus Universitario, Londrina, PR, CEP 86051-990 (Brazil); Nascimento Andrade, Felipe [Programa de Pos-Graduacao em Quimica da Universidade Federal de Alfenas, Rua Gabriel Monteiro da Silva 700, Alfenas, MG, CEP 37130-000 (Brazil); Midori de Oliveira, Fernanda; Zanetti Corazza, Marcela [Departamento de Quimica, Universidade Estadual de Londrina, Rod. Celso Garcia Cid, PR 445 Km 380, Campus Universitario, Londrina, PR, CEP 86051-990 (Brazil); Mendes de Azevedo, Luiz Fernando [Programa de Pos-Graduacao em Quimica da Universidade Federal de Alfenas, Rua Gabriel Monteiro da Silva 700, Alfenas, MG, CEP 37130-000 (Brazil); Gava Segatelli, Mariana [Universidade Tecnologica Federal do Parana (UTFPR), Av. dos Pioneiros 3131, Londrina, PR, CEP 86036-370 (Brazil)
2011-10-10
Highlights: {yields} Ion imprinted hybrid copolymer as selective sorbent for Pb{sup 2+} ions. {yields} The sorbent was at least 10 times more selective than non imprinted copolymer. {yields} A method for Pb{sup 2+} determination by TS-FF-AAS in different samples was developed. {yields} High reusability and chemical stability of ion imprinted hybrid copolymer were observed. - Abstract: A novel ion imprinted polyvinylimidazole-silica hybrid copolymer (IIHC) was synthesized and used as a selective solid sorbent for Pb{sup 2+} ions preconcentration using an on-line solid phase extraction (SPE) system coupled to TS-FF-AAS. The ionic hybrid sorbent was prepared using 1-vinylimidazole and 3-(trimethoxysilyl)propylmethacrylate as monomers, Pb{sup 2+} ions as template, tetraethoxysilane as reticulating agent and 2,2'-azobis-isobutyronitrile as initiator. The best on-line SPE conditions concerning sorption behavior, including sample pH (6.46), buffer concentration (9.0 mmol L{sup -1}), eluent (HNO{sub 3}) concentration (0.5 mol L{sup -1}) and preconcentration flow rate (4.0 mL min{sup -1}), were optimized by means of full factorial design and Doehlert matrix. The analytical curve ranged from 2.5 to 65.0 {mu}g L{sup -1} (r = 0.999) with limit of detection of 0.75 {mu}g L{sup -1}; the precision (repeatability) calculated as relative standard deviation (n = 10) was 5.0 and 3.6% for Pb{sup 2+} concentration of 10.0 and 60.0 {mu}g L{sup -1}, respectively. From on-line breakthrough curve, column capacity was 3.5 mg g{sup -1}. Preconcentration factor (PF), consumptive index (CI) and concentration efficiency (CE) were 128.0, 0.16 mL and 25.6 min{sup -1}, respectively. The selective performance of the sorbent, based on relative selectivity coefficient, was compared to NIC (non imprinted copolymer) for the binary mixture Pb{sup 2+}/Cd{sup 2+}, Pb{sup 2+}/Cu{sup 2+} and Pb{sup 2+}/Zn{sup 2+}. The results showed that ion imprinted polyvinylimidazole-silica hybrid polymer had higher
Krause, Christine; Werner, Hans-Joachim
2012-06-07
Explicitly correlated local coupled-cluster (LCCSD-F12) methods with pair natural orbitals (PNOs), orbital specific virtual orbitals (OSVs), and projected atomic orbitals (PAOs) are compared. In all cases pair-specific virtual subspaces (domains) are used, and the convergence of the correlation energy as a function of the domain sizes is studied. Furthermore, the performance of the methods for reaction energies of 52 reactions involving 58 small and medium sized molecules is investigated. It is demonstrated that for all choices of virtual orbitals much smaller domains are needed in the explicitly correlated methods than without the explicitly correlated terms, since the latter correct a large part of the domain error, as found previously. For PNO-LCCSD-F12 with VTZ-F12 basis sets on the average only 20 PNOs per pair are needed to obtain reaction energies with a root mean square deviation of less than 1 kJ mol(-1) from complete basis set estimates. With OSVs or PAOs at least 4 times larger domains are needed for the same accuracy. A new hybrid method that combines the advantages of the OSV and PNO methods is proposed and tested. While in the current work the different local methods are only simulated using a conventional CCSD program, the implications for low-order scaling local implementations of the various methods are discussed.
Photoassociation of Trilobite Rydberg Molecules via Resonant Spin-Orbit Coupling
Kleinbach, K. S.; Meinert, F.; Engel, F.; Kwon, W. J.; Löw, R.; Pfau, T.; Raithel, G.
2017-06-01
We report on a novel method for the photoassociation of strongly polar trilobite Rydberg molecules. This exotic ultralong-range dimer, consisting of a ground-state atom bound to the Rydberg electron via electron-neutral scattering, inherits its polar character from the admixture of high-angular-momentum electronic orbitals. The absence of low-L character hinders standard photoassociation techniques. Here, we show that for suitable principal quantum numbers the resonant coupling of the orbital motion with the nuclear spin of the perturber, mediated by electron-neutral scattering, hybridizes the trilobite molecular potential with the more conventional S -type molecular state. This provides a general path to associate trilobite molecules with large electric dipole moments, as demonstrated via high-resolution spectroscopy. We find a dipole moment of 135(45) D for the trilobite state. Our results are compared to theoretical predictions based on a Fermi model.
Molecular integrals for exponential-type orbitals using hyperspherical harmonics
DEFF Research Database (Denmark)
Avery, James Emil; Avery, John Scales
2015-01-01
Exponential-type orbitals are better suited to calculations of molecular electronic structure than are Gaussians, since ETO's can accurately represent the behavior of molecular orbitals near to atomic nuclei, as well as their long-distance exponential decay. Orbitals based on Gaussians fail in bo...
Cukrowski, Ignacy; de Lange, Jurgens H; Mitoraj, Mariusz
2014-01-23
In the present account factors determining the stability of ZnL, ZnL2, and ZnL3 complexes (L = bpy, 2,2′-bipyridyl) were characterized on the basis of various techniques: the quantum theory of atoms in molecules (QTAIM), energy decomposition schemes based on interacting quantum atoms (IQA), and extended transition state coupled with natural orbitals for chemical valence (ETS-NOCV). Finally, the noncovalent interactions (NCI) index was also applied. All methods consistently indicated that the strength of the coordination bonds, Zn–O and Zn–N, decreases from ZnL to ZnL3. Importantly, it has been identified that the strength of secondary intramolecular heteropolar hydrogen bonding interactions, CH···O and CH···N, increases when going from ZnL to ZnL3. A similar trend appeared to be valid for the π-bonding as well as electrostatic stabilization. In addition to the above leading bonding contributions, all techniques suggested the existence of very subtle, but non-negligible additional stabilization from the CH···HC electronic exchange channel; these interactions are the weakest among all considered here. From IQA it was found that the local diatomic interaction energy, Eint(H,H), amounts at HF to −2.5, −2.7, and −2.9 kcal mol(–1) for ZnL, ZnL2, and ZnL3, respectively (−2.1 kcal mol(–1) for ZnL at MP2). NOCV-based deformation density channels showed that formation of CH--HC contacts in Zn complexes causes significant polarization of σ(C–H) bonds, which accordingly leads to charge accumulation in the CH···HC bay region. Charge depletion from σ(C–H) bonds was also reflected in the calculated spin–spin (1)J(C–H) coupling constants, which decrease from 177.06 Hz (ZnL) to 173.87 Hz (ZnL3). This last result supports our findings of an increase in the local electronic CH···HC stabilization from ZnL to ZnL3 found from QTAIM, IQA, and ETS-NOCV. Finally, this work unites for the first time the results from four methods that are widely
Energy Technology Data Exchange (ETDEWEB)
Michelotti, L.
1995-01-01
The past fifteen years have witnessed a remarkable development of methods for analyzing single particle orbit dynamics in accelerators. Unlike their more classic counterparts, which act upon differential equations, these methods proceed by manipulating Poincare maps directly. This attribute makes them well matched for studying accelerators whose physics is most naturally modelled in terms of maps, an observation that has been championed most vigorously by Forest. In the following sections the author sketchs a little background, explains some of the physics underlying these techniques, and discusses the best computing strategy for implementing them in conjunction with modeling accelerators.
... Eye Exams, Study Finds Additional Content Medical News Inflammation of the Orbit (Inflammatory Orbital Pseudotumor) By James ... Introduction to Eye Socket Disorders Cavernous Sinus Thrombosis Inflammation of the Orbit Orbital Cellulitis Preseptal Cellulitis Tumors ...
Seyed Hassan Mostafavi
2010-01-01
Preseptal and orbital cellulitis occur more commonly in children than adults. The history and physical examination are crucial in distinguishing between preseptal and orbital cellulitis. The orbital septum delineates the anterior eyelid soft tissues from the orbital soft tissue. Infections anterior to the orbital septum are classified as preseptal cellulitis and those posterior to the orbital septum are termed orbital cellulitis. "nRecognition of orbital involvement is important not only...
Institute of Scientific and Technical Information of China (English)
Won-Sub KWACK; Hyoung-Seok MOON; Seong-Jun JEONG; Qi-min WANG; Se-Hun KWON
2011-01-01
IrO2-TiO2 thin films were prepared by atomic layer deposition using Ir(EtCp)(COD) and titanium isopropoxide (TTIP).in the IrO2-TiO2 thin films. The low temperature coefficient of resistance(TCR) values can be obtained by adopting IrO2-TiO2 composite thin films. Moreover, the change in the resistivity of lrO2-TiO2 thin films was below 10% even after O2 annealing process at 600 ℃. The step stress test results show that IrO2-TiO2 films have better characteristics than conventional TaN08 heater resistor.Therefore, IrO2-TiO2 composite thin films can be used as a heater resistor material in thermal inkjet printhead.
Directory of Open Access Journals (Sweden)
A. Esposito
2016-07-01
Full Text Available We propose a new interpretation of the neutral and charged X,Z exotic hadron resonances. Hybridized-tetraquarks are neither purely compact tetraquark states nor bound or loosely bound molecules but rather a manifestation of the interplay between the two. While meson molecules need a negative or zero binding energy, its counterpart for h-tetraquarks is required to be positive. The formation mechanism of this new class of hadrons is inspired by that of Feshbach metastable states in atomic physics. The recent claim of an exotic resonance in the Bs0π± channel by the D0 Collaboration and the negative result presented subsequently by the LHCb Collaboration are understood in this scheme, together with a considerable portion of available data on X,Z particles. Considerations on a state with the same quantum numbers as the X(5568 are also made.
Esposito, A.; Polosa, A.D.
2016-01-01
We propose a new interpretation of the neutral and charged X, Z exotic hadron resonances. Hybridized-tetraquarks are neither purely compact tetraquark states nor bound or loosely bound molecules. The latter would require a negative or zero binding energy whose counterpart in h-tetraquarks is a positive quantity. The formation mechanism of this new class of hadrons is inspired by that of Feshbach metastable states in atomic physics. The recent claim of an exotic resonance in the Bs pi+- channel by the D0 collaboration and the negative result presented subsequently by the LHCb collaboration are understood in this scheme, together with a considerable portion of available data on X, Z particles. Considerations on a state with the same quantum numbers as the X(5568) are also made.
Nori-Shargh, Davood; Mousavi, Seiedeh Negar; Kayi, Hakan
2014-05-01
Complete basis set CBS-4, hybrid-density functional theory (hybrid-DFT: B3LYP/6-311+G**) based methods and natural bond orbital (NBO) interpretations have been used to examine the contributions of the hyperconjugative, electrostatic, and steric effects on the conformational behaviors of trans-2,3-dihalo-1,4-diselenane [halo = F (1), Cl (2), Br (3)] and trans-2,5-dihalo-1,4-diselenane [halo = F (4), Cl (5), Br (6)]. Both levels of theory showed that the axial conformation stability, compared to its corresponding equatorial conformation, decreases from compounds 1 → 3 and 4 → 6. Based on the results obtained from the NBO analysis, there are significant anomeric effects for compounds 1-6. The anomeric effect associated with the electron delocalization is in favor of the axial conformation and increases from compounds 1 → 3 and 4 → 6. On the other hand, dipole moment differences between the axial and equatorial conformations [Δ(μ(eq)-μ(ax)] decrease from compounds 1 → 3. Although Δ(μ(eq)-μ(ax)) parameter decreases from compound 1 to compound 3, the dipole moment values of the axial conformations are smaller than those of their corresponding equatorial conformations. Therefore, the anomeric effect associated with the electron delocalizations (for halogen-C-Se segments) and the electrostatic model associated with the dipole-dipole interactions fail to account for the increase of the equatorial conformations stability on going from compound 1 to compound 3. Since there is no dipole moment for the axial and equatorial conformations of compounds 4-6, consequently, the conformational preferences in compounds 1-6 is in general dictated by the steric hindrance factor associated with the 1,3-syn-axial repulsions. Importantly, the CBS-4 results show that the entropy difference (∆S) between the equatorial axial conformations increases from compounds 1 → 3 and 4 → 6. This fact can be explained by the anomeric effect associated
Molina, C; Messaddeq, Y; Ribeiro, S J L; Silva, M A P; Zea-Bermudez, V D; Carlos, L D
2003-01-01
Organic-inorganic hybrids, named di-ureasils and described by polyether-based chains grafted to both ends to a siliceous backbone through urea cross linkages, were used as hosts for incorporation of the well-known coordination complex of trivalent europium (Eu sup 3 sup +) ions described by the formula [Eu(TTA) sub 3 (H sub 2 O) sub 2] (where TTA stands for thenoyltrifluoroacetone). By comparing with Eu sup 3 sup + -doped di-ureasil without complex form the new materials prepared here enhanced the quantum efficiency for photoemission of Eu sup 3 sup + ions. The enhancement can be explained by the coordination ability of the organic counterpart of the host structure which is strong enough to displace water molecules in [Eu(TTA) sub 3 (H sub 2 O) sub 2] from the rare earth neighbourhood after the incorporation process. High intensity of Eu sup 3 sup + emission was observed with a low non-radiative decay rate under ultraviolet excitation. The quantum efficiency calculated from the decay of sup 5 D sub 0 emission...
Kim, Y S
2011-01-01
In 1905, Einstein formulated his special relativity for point particles. For those particles, his Lorentz covariance and energy-momentum relation are by now firmly established. How about the hydrogen atom? It is possible to perform Lorentz boosts on the proton assuming that it is a point particle. Then what happens to the electron orbit? The orbit could go through an elliptic deformation, but it is not possible to understand this problem without quantum mechanics, where the orbit is a standing wave leading to a localized probability distribution. Is this concept consistent with Einstein's Lorentz covariance? Dirac, Wigner, and Feynman contributed important building blocks for understanding this problem. The remaining problem is to assemble those blocks to construct a Lorentz-covariant picture of quantum bound states based on standing waves. It is shown possible to assemble those building blocks using harmonic oscillators.
Penteado, Poliana; Egues, J. Carlos
2013-03-01
In condensed matter systems, the coupling between spatial and spin degrees of freedom through the spin-orbit (SO) interaction offers the possibility of manipulating the electron spin via its orbital motion. The proposal by Datta and Das of a `spin transistor' for example, highlights the use of the SO interaction to control the electron spin via electrical means. Recently, arrangements of crossed lasers and magnetic fields have been used to trap and cool atoms in optical lattices and also to create light-induced gauge potentials, which mimic the SO interactions in real solids. In this work, we investigate the Zitterbewegung in cold atoms by starting from the effective SO Hamiltonian derived in Ref.. Cross-dressed atoms as effective spins can provide a proper setting in which to observe this effect, as the relevant parameter range of SO strengths may be more easily attainable in this context. We find a variety of peculiar Zitterbewegung orbits in real and pseudo-spin spaces, e.g., cycloids and ellipses - all of which obtained with realistic parameters. This work is supported by FAPESP, CAPES and CNPq.
Electronic and magnetic properties of 1T-HfS{sub 2} by doping transition-metal atoms
Energy Technology Data Exchange (ETDEWEB)
Zhao, Xu, E-mail: zhaoxu@htu.cn [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Wang, Tianxing; Wang, Guangtao [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Dai, Xianqi [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Department of Physics, Zhengzhou Normal University, Zhengzhou, Henan 450044 (China); Xia, Congxin [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Yang, Lin [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang 453007 (China)
2016-10-15
Highlights: • Pristine 1T-HfS{sub 2} is a semiconductor with indirect gaps of 1.250 eV • Magnetism can be observed for V, Cr, Mn, Fe, Co, and Cu doping. • Strong p–d hybridization was found between TM 3d orbitals and S 3p orbitals. • V-doped 1T-HfS{sub 2} is ideal for spin injection. - Abstract: We explored the electronic and magnetic properties of 1T-HfS{sub 2} doped by transition metal (TM) atom using the first-principles calculation. We doped the transition metal atoms from the IIIB to VIB groups in nonmagnetic 1T-HfS{sub 2}. Numerical results show that the pristine 1T-HfS{sub 2} is a semiconductor with indirect gaps of 1.250 eV. Magnetism can be observed for V, Cr, Mn, Fe, Co, and Cu doping. The polarized charges mainly arise from the localized 3d electrons of the TM atom. The strong p–d hybridization was found between the 3d orbitals of TM and 3p orbitals of S. The substituted 1T-HfS{sub 2} can be a metal, semiconductor or half-metal. Analysis of the band structure and magnetic properties indicates that TM-doped HfS{sub 2} (TM = V, Fe, Cu) are promising systems to explore two-dimensional diluted magnetic semiconductors. The formation energy calculations also indicate that it is energetically favorable and relatively easier to incorporate transition metal atom into the HfS{sub 2} under S-rich experimental conditions. In contrast, V-doped HfS{sub 2} has relatively wide half-metallic gap and low formation energy. So V-doped 1T-HfS{sub 2} is ideal for spin injection, which is important for application in semiconductor spintronics.
Borbolla-Pertierra, A M; Morales-Baños, D R; Martínez-Nava, L R; Garrido-Sánchez, G A; López-Hernández, C M; Velasco-Ramos, P
2017-02-01
The case is presented of a 46-year-old male with right eye proptosis and conjunctival hyperaemia, of 18 months onset. A well-defined intraconal mass was found in the computed tomography. In magnetic resonance this was hypo-intense on T1, enhanced with gadolinium and hyperintense on T2. Excisional biopsy was performed, which was reported as a well-differentiated liposarcoma in the histopathology study. Liposarcoma is a malignant adipose tissue tumour. It is very rare in the orbit, with 5 histological types, the most common being myxoid. The treatment of choice is wide surgical excision and may be accompanied with radiotherapy. As it is an infiltrative tumour, It has a high rate of recurrence. Copyright © 2016 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.
Spin-Orbit Coupled Bose-Einstein Condensates
2016-11-03
Spin -Orbit Coupled Bose-Einstein Condensates This ARO research proposal entitled " SPIN -ORBIT COUPLED BOSE-EINSTEIN CONDENSATES" (SOBECs) explored...realized with cold atoms. A unique feature of the SOBECs is a topologically protected spin -orbital degeneracy of the ground state that results in a...Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 superfluids, spin -orbit coupling, optical lattices, topological states REPORT
Lipatov, A S; Paterson, W R; Sittler, E C; Hartle, R E; Simpson, D G
2012-01-01
The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa moon-magnetosphere system with respect a to variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo Orbiter mission, and for planning flyby and orbital measurements (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy et al., 2007; Shematovich et al., 2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyroradius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream backgr...
Geology orbiter comparison study
Cutts, J. A. J.; Blasius, K. R.; Davis, D. R.; Pang, K. D.; Shreve, D. C.
1977-01-01
Instrument requirements of planetary geology orbiters were examined with the objective of determining the feasibility of applying standard instrument designs to a host of terrestrial targets. Within the basic discipline area of geochemistry, gamma-ray, X-ray fluorescence, and atomic spectroscopy remote sensing techniques were considered. Within the discipline area of geophysics, the complementary techniques of gravimetry and radar were studied. Experiments using these techniques were analyzed for comparison at the Moon, Mercury, Mars and the Galilean satellites. On the basis of these comparative assessments, the adaptability of each sensing technique was judged as a basic technique for many targets, as a single instrument applied to many targets, as a single instrument used in different mission modes, and as an instrument capability for nongeoscience objectives.
Huhn, William P.; Blum, Volker
2017-08-01
We quantify the accuracy of different non-self-consistent and self-consistent spin-orbit coupling (SOC) treatments in Kohn-Sham and hybrid density functional theory by providing a band-structure benchmark set for the valence and low-lying conduction energy bands of 103 inorganic compounds, covering chemical elements up to polonium. Reference energy band structures for the PBE density functional are obtained using the full-potential (linearized) augmented plane wave code wien2k, employing its self-consistent treatment of SOC including Dirac-type p1 /2 orbitals in the basis set. We use this benchmark set to benchmark a computationally simpler, non-self-consistent all-electron treatment of SOC based on scalar-relativistic orbitals and numeric atom-centered orbital basis functions. For elements up to Z ≈50 , both treatments agree virtually exactly. For the heaviest elements considered (Tl, Pb, Bi, Po), the band-structure changes due to SOC are captured with a relative deviation of 11% or less. For different density functionals (PBE versus the hybrid HSE06), we show that the effect of spin-orbit coupling is usually similar but can be dissimilar if the qualitative features of the predicted underlying scalar-relativistic band structures do not agree. All band structures considered in this work are available online via the NOMAD repository to aid in future benchmark studies and methods development.
New hybrid lead iodides: From one-dimensional chain to two-dimensional layered perovskite structure
Energy Technology Data Exchange (ETDEWEB)
Xiong, Kecai; Liu, Wei [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States); Teat, Simon J. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); An, Litao; Wang, Hao; Emge, Thomas J. [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States); Li, Jing, E-mail: jingli@rutgers.edu [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States)
2015-10-15
Two new hybrid lead halides (H{sub 2}BDA)[PbI{sub 4}] (1) (H{sub 2}BDA=1,4-butanediammonium dication) and (HNPEIM)[PbI{sub 3}] (2) (HNPEIM=N-phenyl-ethanimidamidine cation) have been synthesized and structurally characterized. X-ray diffraction analyses reveal that compound 1 features a two-dimensional corner-sharing perovskite layer whereas compound 2 contains one-dimensional edge-sharing double chains. The N-phenyl-ethanimidamidine cation within compound 2 was generated in-situ under solvothermal conditions. The optical absorption spectra collected at room temperature suggest that both compounds are semiconductors having direct band gaps, with estimated values of 2.64 and 2.73 eV for 1 and 2, respectively. Results from the density functional theory (DFT) calculations are consistent with the experimental data. Density of states (DOS) analysis reveals that in both compounds 1 and 2, the energy states in the valence band maximum region are iodine 5p atomic orbitals with a small contribution from lead 6s, while in the region of conduction band minimum, the major contributions are from the inorganic (Pb 6p atomic orbitals) and organic components (C and N 2p atomic orbitals) in compound 1 and 2, respectively. - Graphical abstract: Two new hybrid lead halides built on one-dimensional edge-sharing double chains and two-dimensional corner-sharing perovskite layers are synthesized and their structural and electronic properties are analyzed. - Highlights: • Two new hybrid lead iodides are designed, synthesized, and characterized. • They are closely related to, but different from, perovskite structures. • The electronic properties of both compounds are analyzed by DFT calculations.
Optical nanofibres and neutral atoms
Nieddu, Thomas; Chormaic, Sile Nic
2015-01-01
Optical nanofibres are increasingly being used in cold atom experiments due to their versatility and the clear advantages they have when developing all-fibred systems for quantum technologies. They provide researchers with a method of overcoming the Rayleigh range for achieving high intensities in a focussed beam over a relatively long distance, and can act as a noninvasive tool for probing cold atoms. In this review article, we will briefly introduce the theory of mode propagation in an ultrathin optical fibre and highlight some of the more significant theoretical and experimental progresses to date, including the early work on atom probing, manipulation and trapping, the study of atom-dielectric surface interactions, and the more recent observation of nanofibre-mediated nonlinear optics phenomena in atomic media. The functionality of optical nanofibres in relation to the realisation of atom-photon hybrid quantum systems is also becoming more evident as some of the earlier technical challenges are surpassed ...
Rahimi, A.; Mao, S.; Kawata, D.
2014-03-01
The fossil record shows that the Earth has experienced several mass extinctions over the past 500 million years1, and it has been suggested that there is a periodicity in extinction events on timescales of tens1 and/or hundreds of millions of years. Various hypotheses have been proposed to explain the cause of the mass extinctions, including the suggestion that the Earth's ozone layer may have been destroyed by intense radiation from a nearby supernovae2- 3, exposing the Earth's surface to damaging UV radiation. Recent observations of cores taken from the ocean floor revealed atoms of a very rare isotope of iron (60Fe) believed to have arrived on Earth around 2 million years ago as fallout from a nearby supernovae4. Astronomical evidence for that past supernovae was recently found in the debris of a young cluster of massive stars5, by tracing its past orbit, putting it at the right place at the right time to explain the mild extinction event. Here we report new high-resolution (both in space and time) N-body chemodynamical simulations (carried out with our novel code GCD+6) of the evolution of a model Milky Way Galaxy, tracing the orbit of èsun-like' stars over a 500 million year period, checking the proximity to supernovae throughout the history of the orbit and comparing the times when this occurs with past mass extinctions on Earth. We additionally explain the important effects of the spiral arm pattern, radial migration of stars and Galactic chemistry on habitability.
Nigam, Sandeep; Majumder, Chiranjib
2010-11-03
Using state-of-the-art first-principles calculations we report the interaction of M atoms (M = Cu, Ag and Au) with small Ag(n), Au(n) clusters (n = 3 and 6) and periodic Ag(111) and Au(111) surfaces. All calculations were performed using the plane wave pseudo-potential approach under the spin polarized version of the generalized gradient approximation scheme. The result shows that the equilibrium geometry of all MAg(3) and MAu(3) clusters favor a planar rhombus structure. From the charge distribution analysis of MAg(n)/MAu(n) clusters it is found that, while Cu and Ag donates electronic charge towards the host clusters, the Au atom acts as an acceptor, thus creating charge polarization in the system. The difference in orbital decomposed charges before and after the M interaction reveals that enhanced s-d hybridization is responsible for keeping the MAu(6) cluster planar, and increased p-orbital participation induces three-dimensional configurations in MAg(6) clusters. The optimization of M atom deposition on the Ag(111) and Au(111) surfaces shows that M atoms prefer to adsorb on the threefold fcc site over other well-defined sites. From the orbital decomposed charge analysis it is inferred that, although there is significant difference in the absolute magnitude of the interaction energy between M atoms and the Ag or Au substrates, the nature of chemical bonding is similar for the finite size clusters as well as in slab models.
Borsten, L; Ferrara, S; Marrani, A; Rubens, W
2012-01-01
We study both the "large" and "small" U-duality charge orbits of extremal black holes appearing in D = 5 and D = 4 Maxwell-Einstein supergravity theories with symmetric scalar manifolds. We exploit a formalism based on cubic Jordan algebras and their associated Freudenthal triple systems, in order to derive the minimal charge representatives, their stabilizers and the associated "moduli spaces". After recalling N = 8 maximal supergravity, we consider N = 2 and N = 4 theories coupled to an arbitrary number of vector multiplets, as well as N = 2 magic, STU, ST^2 and T^3 models. While the STU model may be considered as part of the general N = 2 sequence, albeit with an additional triality symmetry, the ST^2 and T^3 models demand a separate treatment, since their representative Jordan algebras are Euclidean or only admit non-zero elements of rank 3, respectively. Finally, we also consider minimally coupled N = 2, matter coupled N = 3, and "pure" N = 5 theories.
Continuation of Sets of Constrained Orbit Segments
DEFF Research Database (Denmark)
Schilder, Frank; Brøns, Morten; Chamoun, George Chaouki;
Sets of constrained orbit segments of time continuous flows are collections of trajectories that represent a whole or parts of an invariant set. A non-trivial but simple example is a homoclinic orbit. A typical representation of this set consists of an equilibrium point of the flow and a trajectory...... that starts close and returns close to this fixed point within finite time. More complicated examples are hybrid periodic orbits of piecewise smooth systems or quasi-periodic invariant tori. Even though it is possible to define generalised two-point boundary value problems for computing sets of constrained...... orbit segments, this is very disadvantageous in practice. In this talk we will present an algorithm that allows the efficient continuation of sets of constrained orbit segments together with the solution of the full variational problem....
A Hybrid Decomposition Parallel Implementation of the Car-Parrinello Method
Wiggs, J K; Wiggs, James K.; Jonsson, Hannes
1994-01-01
We have developed a flexible hybrid decomposition parallel implementation of the first-principles molecular dynamics algorithm of Car and Parrinello. The code allows the problem to be decomposed either spatially, over the electronic orbitals, or any combination of the two. Performance statistics for 32, 64, 128 and 512 Si atom runs on the Touchstone Delta and Intel Paragon parallel supercomputers and comparison with the performance of an optimized code running the smaller systems on the Cray Y-MP and C90 are presented.
Ferromagnetism carried by highly delocalized hybrid states in Sc-doped ZnO thin films
Benali Kanoun, Mohammed
2012-05-29
We present first-principles results for Sc-doped ZnOthin films. Neighboring Sc atoms in the surface and/or subsurface layers are found to be coupled ferromagnetically, where only two of the possible configurations induce spin polarization. In the first configuration, the polarization is carried by the Sc d states as expected for transition metaldoping. However, there is a second configuration which is energetically favorable. It is governed by polarized hybrid states of the Zns, O p, and Sc d orbitals. Such highly delocalized states can be an important ingredient for understanding the magnetism of dopedZnOthin films.
1996-01-01
Interviews following the 1991 co-operation Agreement between the Department of Atomic Energy (DAE) of the Government of India and the European Organization for Nuclear Research (CERN) concerning the participation in the Large Hadron Collider Project (LHC) . With Chidambaram, R, Chairman, Atomic Energy Commission and Secretary, Department of Atomic Energy, Department of Atomic Energy (DAE) of the Government of India and Professor Llewellyn-Smith, Christopher H, Director-General, CERN.
Reichel, Jakob
2010-01-01
This book provides a stimulating and multifaceted picture of a rapidly developing field. The first part reviews fundamentals of atom chip research in tutorial style, while subsequent parts focus on the topics of atom-surface interaction, coherence on atom chips, and possible future directions of atom chip research. The articles are written by leading researchers in the field in their characteristic and individual styles.
Institute of Scientific and Technical Information of China (English)
Nila; F.Moeloek
1993-01-01
Orbital anatomy, the clinical features of orbital tumors, the recent development of the diagnosis and management of orbital tumors were described. The incidence of orbital tumors in Dr. Cipto Mangunkusumo Hospital in the past years were introduced. The principle of management of orbital tumors and their prognosis were discussed.
Advanced Vortex Hybrid Rocket Engine (AVHRE) Project
National Aeronautics and Space Administration — Orbital Technologies Corporation (ORBITEC) proposes to develop a unique Advanced Vortex Hybrid Rocket Engine (AVHRE) to achieve a highly-reliable, low-cost and...
Energy Technology Data Exchange (ETDEWEB)
Safronova, M. S. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Clark, Charles W. [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899-8410 (United States); Kozlov, M. G. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation)
2015-01-22
The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.
Directory of Open Access Journals (Sweden)
Seyed Hassan Mostafavi
2010-05-01
Full Text Available Preseptal and orbital cellulitis occur more commonly in children than adults. The history and physical examination are crucial in distinguishing between preseptal and orbital cellulitis. The orbital septum delineates the anterior eyelid soft tissues from the orbital soft tissue. Infections anterior to the orbital septum are classified as preseptal cellulitis and those posterior to the orbital septum are termed orbital cellulitis. "nRecognition of orbital involvement is important not only because of the threatened vision loss associated with orbital cellulitis but also because of the potential for central nervous system complications including cavernous sinus thrombosis, meningitis, and death. "nOrbital imaging should be obtained in all patients suspected of having orbital cellulitis. CT is preferred to MR imaging, as the orbital tissues have high con-trast and the bone can be well visualized. Orbital CT scanning allows localization of the disease process to the preseptal area, the extraconal or intraconal fat, or the subperiosteal space. Axial CT views allow evaluation of the medial orbit and ethmoid sinuses, whereas coronal scans image the orbital roof and floor and the frontal and maxillary sinuses. If direct coronal imaging is not possible, reconstruction of thin axial cuts may help the assessment of the orbital roof and floor. Potential sources of orbital cellulitis such as sinusitis, dental infection, and facial cellulitis are often detectable on CT imaging. "nIn this presentation, the imaging considerations of the orbital infections; including imaging differentiation criteria of all types of orbital infections are reviewed.
Preseptal Cellulitis, Orbital Cellulitis, Orbital Abscess
Rana Altan Yaycıoğlu
2012-01-01
Patients with orbital infections present to our clinic usually with unilateral pain, hyperemia, and edema of the eyelids. The differentiation between preseptal and orbital cellulitis is utmost important in that the second requires hospitalization. Since in orbital cellulitis, the tissues posterior to the orbital septum are involved, signs such as conjunctival chemosis, limited eye movement, decreased vision, as well as afferent pupil defect secondary to optic nerve involvement may al...
Bilateral orbital cavernous haemangiomas.
Fries, P D; Char, D. H.
1988-01-01
Simultaneous bilateral orbital lesions are rare. The differential diagnosis includes orbital pseudotumour, metastasis, leukaemia, lymphoma, Wegener's granulomatosis, and neurofibromatosis. We report what we believe to be the first case of bilateral orbital cavernous haemangiomas.
DEFF Research Database (Denmark)
Krüger, Peter; Hofferberth, S.; Haller, E.
2005-01-01
Miniaturized potentials near the surface of atom chips can be used as flexible and versatile tools for the manipulation of ultracold atoms on a microscale. The full scope of possibilities is only accessible if atom-surface distances can be reduced to microns. We discuss experiments in this regime...
A Simple Relativistic Bohr Atom
Terzis, Andreas F.
2008-01-01
A simple concise relativistic modification of the standard Bohr model for hydrogen-like atoms with circular orbits is presented. As the derivation requires basic knowledge of classical and relativistic mechanics, it can be taught in standard courses in modern physics and introductory quantum mechanics. In addition, it can be shown in a class that…
A Simple Relativistic Bohr Atom
Terzis, Andreas F.
2008-01-01
A simple concise relativistic modification of the standard Bohr model for hydrogen-like atoms with circular orbits is presented. As the derivation requires basic knowledge of classical and relativistic mechanics, it can be taught in standard courses in modern physics and introductory quantum mechanics. In addition, it can be shown in a class that…
Energy Technology Data Exchange (ETDEWEB)
Yilmaz, Erkan [Department of Chemistry, Faculty of Sciences, Erciyes University, Kayseri 38039 (Turkey); Ocsoy, Ismail [Department of Analytical Chemistry, Faculty of Pharmacy, Erciyes University, Kayseri 38039 (Turkey); Nanotechnology Research Center (ERNAM), Erciyes University, Kayseri 38039 (Turkey); Ozdemir, Nalan [Department of Chemistry, Faculty of Sciences, Erciyes University, Kayseri 38039 (Turkey); Soylak, Mustafa, E-mail: soylak@erciyes.edu.tr [Department of Chemistry, Faculty of Sciences, Erciyes University, Kayseri 38039 (Turkey)
2016-02-04
Herein, the synthesis of bovine serum albumin-Cu(II) hybrid nanoflowers (BSA-NFs) through the building blocks of bovine serum albumin (BSA) and copper(II) ions in phosphate buffered saline (PBS) and their use as adsorbent for cadmium and lead ions are reported. The BSA-NFs, for the first time, were efficiently utilized as novel adsorbent for solid phase extraction (SPE) of cadmium and lead ions in water, food, cigarette and hair samples. The method is based on the separation and pre-concentration of Cd(II) and Pb(II) by BSA-NFs prior to determination by slurry analysis via flame atomic absorption spectrometry (FAAS). The analytes were adsorbed on BSA-NFs under the vortex mixing and then the ion-loaded slurry was separated and directly introduced into the flame AAS nebulizer by using a hand-made micro sample introduction system to eliminate a number of drawbacks. The effects of analytical key parameters, such as pH, amount of BSA-NFs, vortexing time, sample volume, and matrix effect of foreign ions on adsorbing of Cd(II) and Pb(II) were systematically investigated and optimized. The limits of detection (LODs) for Cd(II) and Pb(II) were calculated as 0.37 μg L{sup −1} and 8.8 μg L{sup −1}, respectively. The relative standard deviation percentages (RSDs) (N = 5) for Cd(II) and Pb(II) were 7.2%, and 5.0%, respectively. The accuracy of the developed procedure was validated by the analysis of certified reference materials (TMDA-53.3 Fortified Water, TMDA-70 Fortified Water, SPS-WW2 Waste Water, NCSDC-73349 Bush Branches and Leaves) and by addition/recovery analysis. The quantitative recoveries were obtained for the analysis of certified reference materials and addition/recovery tests. The method was successfully applied to the analysis of cadmium and lead in water, food, cigarette and hair samples. - Highlights: • The synthesis of bovine serum albumin-Cu(II) hybrid nanoflowers is reported. • The nanoflowers were utilized for solid phase microextraction of
Noguchi, Ryo; Kuroda, Kenta; Yaji, K.; Kobayashi, K.; Sakano, M.; Harasawa, A.; Kondo, Takeshi; Komori, F.; Shin, S.
2017-01-01
We use spin- and angle-resolved photoemission spectroscopy (SARPES) combined with a polarization-variable laser and investigate the spin-orbit coupling effect under interband hybridization of Rashba spin-split states for the surface alloys Bi/Ag(111) and Bi/Cu(111). In addition to the conventional band mapping of photoemission for Rashba spin splitting, the different orbital and spin parts of the surface wave function are directly imaged into energy-momentum space. It is unambiguously revealed that the interband spin-orbit coupling modifies the spin and orbital character of the Rashba surface states leading to the enriched spin-orbital entanglement and the pronounced momentum dependence of the spin polarization. The hybridization thus strongly deviates the spin and orbital characters from the standard Rashba model. The complex spin texture under interband spin-orbit hybridization proposed by first-principles calculation is experimentally unraveled by SARPES with a combination of p - and s -polarized light.
Josefsson, Ida; Kunnus, Kristjan; Schreck, Simon; Foehlisch, Alexander; de Groot, Frank; Wernet, Philippe; Odelius, Michael
2012-01-01
A new ab initio approach to the calculation of X-ray spectra is demonstrated. It combines a high-level quantum chemical description of the chemical interactions and local atomic multiplet effects. We show here calculated L-edge X-ray absorption (XA) and resonant inelastic X-ray scattering spectra fo
Surface modelling on heavy atom crystalline compounds: HfO{sub 2} and UO{sub 2} fluorite structures
Energy Technology Data Exchange (ETDEWEB)
Evarestov, Robert [Department of Quantum Chemistry, St. Petersburg State University, 26 Universitetsky Prospect, Peterhof, St. Petersburg 198504 (Russian Federation)], E-mail: re1973@re1973.spb.edu; Bandura, Andrei; Blokhin, Eugeny [Department of Quantum Chemistry, St. Petersburg State University, 26 Universitetsky Prospect, Peterhof, St. Petersburg 198504 (Russian Federation)
2009-01-15
The study of the bulk and surface properties of cubic (fluorite structure) HfO{sub 2} and UO{sub 2} was performed using the hybrid Hartree-Fock density functional theory linear combination of atomic orbitals simulations via the CRYSTAL06 computer code. The Stuttgart small-core pseudopotentials and corresponding basis sets were used for the core-valence interactions. The influence of relativistic effects on the structure and properties of the systems was studied. It was found that surface properties of Mott-Hubbard dielectric UO{sub 2} differ from those found for other metal oxides with the closed-shell configuration of d-electrons.
Biswas, P K; Gogonea, Valentin
2008-10-21
We present an ab initio polarizable representation of classical molecular mechanics (MM) atoms by employing an angular momentum-based expansion scheme of the point charges into partial wave orbitals. The charge density represented by these orbitals can be fully polarized, and for hybrid quantum-mechanical-molecular-mechanical (QM/MM) calculations, mutual polarization within the QM/MM Hamiltonian can be obtained. We present the mathematical formulation and the analytical expressions for the energy and forces pertaining to the method. We further develop a variational scheme to appropriately determine the expansion coefficients and then validate the method by considering polarizations of ions by the QM system employing the hybrid GROMACS-CPMD QM/MM program. Finally, we present a simpler prescription for adding isotropic polarizability to MM atoms in a QM/MM simulation. Employing this simpler scheme, we present QM/MM energy minimization results for the classic case of a water dimer and a hydrogen sulfide dimer. Also, we present single-point QM/MM results with and without the polarization to study the change in the ionization potential of tetrahydrobiopterin (BH(4)) in water and the change in the interaction energy of solvated BH(4) (described by MM) with the P(450) heme described by QM. The model can be employed for the development of an extensive classical polarizable force-field.
Spontaneous emission of two interacting atoms near an interface
Institute of Scientific and Technical Information of China (English)
Dehua Wang
2009-01-01
The spontaneous emission rate of two interacting excited atoms near a dielectric interface is studied using the photon closed-orbit theory and the dipole image method.The total emission rate of one atom during the emission process is calculated as a function of the distance between the atom and the interface.The results suggest that the spontaneous emission rate depends not only on the atomic-interface distances,but also on the orientation of the two atomic dipoles and the initial distance between the two atoms.The oscillation in the spontaneous emission rate is caused by the interference between the outgoing electromagnetic wave emitted from one atom and other waves arriving at this atom after traveling along various classical orbits.Each peak in the Fourier transformed spontaneous emission rate corresponds with one action of photon classical orbit.
Page, P R
2003-01-01
We review the status of hybrid baryons. The only known way to study hybrids rigorously is via excited adiabatic potentials. Hybrids can be modelled by both the bag and flux-tube models. The low-lying hybrid baryon is N 1/2^+ with a mass of 1.5-1.8 GeV. Hybrid baryons can be produced in the glue-rich processes of diffractive gamma N and pi N production, Psi decays and p pbar annihilation.
Yamanaka, Takamitsu; Ahart, Muhtar; Mao, Ho-kwang; Suzuki, Takeyuki
2017-01-01
We execute electron density analysis of SrTiO3 at low temperatures up 80 K and high pressures up to 11.88 GPa using X-ray single-crystal diffraction and ab initio quantum chemical molecular orbital (MO) calculation. By changing pressures, the cubic SrTiO3 with perovskite structure goes through a antiferroelastic distortion to tetragonal symmetry above the critical pressure Pc=7 GPa with c/a1 and increasing with lowering temperature. Difference Fourier (D-F) synthesis experimentally proves the residual electron densities Δρ(xyz) are associated with two different effects: electron hybridization bonding electron and anharmonic thermal vibration atoms. The d-p-π hybridization between Ti(3d) and O(2p) orbitals is confirmed in the residual electron density, which is deformed from the ideal spherical density conducted by the atomic scattering factor fi using Hartree-Fock (HF) approximation. MO calculation also reveals the electron hybridization. Anharmonic thermal vibration of atoms yields a large effect to the structure transition. Mulliken charges analysis of MO calculation indicates much smaller charges than their formal ionic charges. Their ionicity increases from cubic to tetragonal above Pc and below Tc.
(Hybrid) Baryons Quantum Numbers and Adiabatic Potentials
Page, P R
1999-01-01
We construct (hybrid) baryons in the flux-tube model of Isgur and Paton. In the limit of adiabatic quark motion, we build proper eigenstates of orbital angular momentum and indicate the flavour, spin, chirality and J^P of (hybrid) baryons. The adiabatic potential is calculated as a function of the quark positions.
Variational electrodynamics of Atoms
De Luca, Jayme
2013-01-01
We study extrema with velocity discontinuities for the variational electromagnetic two-body problem. Along $C^2$ segments, these broken extrema satisfy the Euler-Lagrange equations of the variational principle, which are neutral differential delay equations with state-dependent deviating arguments. At points where accelerations are not defined and velocities are discontinuous, broken extrema satisfy Weierstrass-Erdmann corner conditions that energies and momenta are continuous. Here we construct periodic broken extrema near the $C^{\\infty}$ two-body circular orbits, using piecewise-defined $C^2$ solutions of the neutral differential delay equations along regular segments and a variational approximation for the boundary-layer segments. Broken periodic extrema with an integer number of corner points bifurcate from a discrete set of circular orbits, with scales defined by the Weierstrass-Erdmann corner conditions. We consider the three cases of hydrogen, muonium and positronium atoms. In each case the broken ext...
Orbital dystopia due to orbital roof defect.
Rha, Eun Young; Joo, Hong Sil; Byeon, Jun Hee
2013-01-01
We performed a retrospective review of patients who presented with delayed dystopia as a consequence of an orbital roof defect due to fractures and nontraumatic causes to search for a correlation between orbital roof defect size and surgical indications for the treatment thereof. Retrospective analyses were performed in 7 patients, all of whom presented with delayed dystopia due to orbital roof defects, between January 2001 and June 2011. The causes of orbital roof defects were displaced orbital roof fractures (5 cases), tumor (1 case), and congenital sphenoid dysplasia (1 case). All 7 patients had initially been treated conservatively and later presented with significant dystopia. The sizes of the defects were calculated on computed tomographic scans. Among the 7 patients, aspiration of cerebrospinal fluid, which caused ocular symptoms, in 1 patient with minimal displaced orbital roof and reconstruction with calvarial bone, titanium micromesh, or Medpor in 6 other patients were performed. The minimal size of the orbital roof in patients who underwent orbital roof reconstruction was 1.2 cm (defect height) x 1.0 cm (defect length), 0.94 cm(2). For all patients with orbital dystopia, displacement of the globe was corrected without any complications, regardless of whether the patient was evaluated grossly or by radiology. In this retrospective study, continuous monitoring of clinical signs and active surgical management should be considered for cases in which an orbital roof defect is detected, even if no definite symptoms are noted, to prevent delayed sequelae.
Similarity of atoms in molecules
Energy Technology Data Exchange (ETDEWEB)
Cioslowski, J.; Nanayakkara, A. (Florida State Univ., Tallahassee, FL (United States))
1993-12-01
Similarity of atoms in molecules is quantitatively assessed with a measure that employs electron densities within respective atomic basins. This atomic similarity measure does not rely on arbitrary assumptions concerning basis functions or 'atomic orbitals', is relatively inexpensive to compute, and has straightforward interpretation. Inspection of similarities between pairs of carbon, hydrogen, and fluorine atoms in the CH[sub 4], CH[sub 3]F, CH[sub 2]F[sub 2], CHF[sub 3], CF[sub 4], C[sub 2]H[sub 2], C[sub 2]H[sub 4], and C[sub 2]H[sub 6] molecules, calculated at the MP2/6-311G[sup **] level of theory, reveals that the atomic similarity is greatly reduced by a change in the number or the character of ligands (i.e. the atoms with nuclei linked through bond paths to the nucleus of the atom in question). On the other hand, atoms with formally identical (i.e. having the same nuclei and numbers of ligands) ligands resemble each other to a large degree, with the similarity indices greater than 0.95 for hydrogens and 0.99 for non-hydrogens. 19 refs., 6 tabs.
Operation of the computer model for direct atomic oxygen exposure of Earth satellites
Bourassa, R. J.; Gruenbaum, P. E.; Gillis, J. R.; Hargraves, C. R.
1995-01-01
One of the primary causes of material degradation in low Earth orbit (LEO) is exposure to atomic oxygen. When atomic oxygen molecules collide with an orbiting spacecraft, the relative velocity is 7 to 8 km/sec and the collision energy is 4 to 5 eV per atom. Under these conditions, atomic oxygen may initiate a number of chemical and physical reactions with exposed materials. These reactions contribute to material degradation, surface erosion, and contamination. Interpretation of these effects on materials and the design of space hardware to withstand on-orbit conditions requires quantitative knowledge of the atomic oxygen exposure environment. Atomic oxygen flux is a function of orbit altitude, the orientation of the orbit plan to the Sun, solar and geomagnetic activity, and the angle between exposed surfaces and the spacecraft heading. We have developed a computer model to predict the atomic oxygen exposure of spacecraft in low Earth orbit. The application of this computer model is discussed.
Hybridizing matter-wave and classical accelerometers
Lautier, J.; Volodimer, L.; Hardin, T.; Merlet, S.; Lours, M.; Pereira Dos Santos, F.; Landragin, A.
2014-10-01
We demonstrate a hybrid accelerometer that benefits from the advantages of both conventional and atomic sensors in terms of bandwidth (DC to 430 Hz) and long term stability. First, the use of a real time correction of the atom interferometer phase by the signal from the classical accelerometer enables to run it at best performance without any isolation platform. Second, a servo-lock of the DC component of the conventional sensor output signal by the atomic one realizes a hybrid sensor. This method paves the way for applications in geophysics and in inertial navigation as it overcomes the main limitation of atomic accelerometers, namely, the dead times between consecutive measurements.
Hybridizing matter-wave and classical accelerometers
Energy Technology Data Exchange (ETDEWEB)
Lautier, J.; Volodimer, L.; Hardin, T.; Merlet, S.; Lours, M.; Pereira Dos Santos, F.; Landragin, A., E-mail: arnaud.landragin@obspm.fr [LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 avenue de l' Observatoire, 75014 Paris (France)
2014-10-06
We demonstrate a hybrid accelerometer that benefits from the advantages of both conventional and atomic sensors in terms of bandwidth (DC to 430 Hz) and long term stability. First, the use of a real time correction of the atom interferometer phase by the signal from the classical accelerometer enables to run it at best performance without any isolation platform. Second, a servo-lock of the DC component of the conventional sensor output signal by the atomic one realizes a hybrid sensor. This method paves the way for applications in geophysics and in inertial navigation as it overcomes the main limitation of atomic accelerometers, namely, the dead times between consecutive measurements.
Hybridizing matter-wave and classical accelerometers
Lautier, Jean; Hardin, Thomas; Merlet, Sebastien; Santos, Franck Pereira Dos; Landragin, Arnaud
2014-01-01
We demonstrate a hybrid accelerometer that benefits from the advantages of both conventional and atomic sensors in terms of bandwidth (DC to 430 Hz) and long term stability. First, the use of a real time correction of the atom interferometer phase by the signal from the classical accelerometer enables to run it at best performances without any isolation platform. Second, a servo-lock of the DC component of the conventional sensor output signal by the atomic one realizes a hybrid sensor. This method paves the way for applications in geophysics and in inertial navigation as it overcomes the main limitation of atomic accelerometers, namely the dead times between consecutive measurements.
Orbital Magnetism of Bloch Electrons: III. Application to Graphene
Ogata, Masao
2016-10-01
The orbital susceptibility for graphene is calculated exactly up to the first order with respect to the overlap integrals between neighboring atomic orbitals. The general and rigorous theory of orbital susceptibility developed in the preceding paper is applied to a model for graphene as a typical two-band model. It is found that there are contributions from interband, Fermi surface, and occupied states in addition to the Landau-Peierls orbital susceptibility. The relative phase between the atomic orbitals on the two sublattices related to the chirality of Dirac cones plays an important role. It is shown that there are some additional contributions to the orbital susceptibility that are not included in the previous calculations using the Peierls phase in the tight-binding model for graphene. The physical origin of this difference is clarified in terms of the corrections to the Peierls phase.
Born, Max
1989-01-01
The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.
Imboden, Matthias; Pardo, Flavio; Bolle, Cristian; Han, Han; Tareen, Ammar; Chang, Jackson; Christopher, Jason; Corman, Benjamin; Bishop, David
2013-03-01
Here we present a MEMS based method to fabricate devices with a small number of atoms. In standard semiconductor fabrication, a large amount of material is deposited, after which etching removes what is not wanted. This technique breaks down for structures that approach the single atom limit, as it is inconceivable to etch away all but one atom. What is needed is a bottom up method with single or near single atom precision. We demonstrate a MEMS device that enables nanometer position controlled deposition of gold atoms. A digitally driven plate is swept as a flux of gold atoms passes through an aperture. Appling voltages on four comb capacitors connected to the central plate by tethers enable nanometer lateral precision in the xy plane over 15x15 sq. microns. Typical MEMS structures have manufacturing resolutions on the order of a micron. Using a FIB it is possible to mill apertures as small as 10 nm in diameter. Assuming a low incident atomic flux, as well as an integrated MEMS based shutter with microsecond response time, it becomes possible to deposit single atoms. Due to their small size and low power consumption, such nano-printers can be mounted directly in a cryogenic system at ultrahigh vacuum to deposit clean quench condensed metallic structures.
Controlling the Orbital Sequence in Individual Cu-Phthalocyanine Molecules
Uhlmann, C.; Swart, I.; Repp, J.
2013-01-01
We report on the controlled change of the energetic ordering of molecular orbitals. Negatively charged copper(II)phthalocyanine on NaCl/Cu(100) undergoes a Jahn–Teller distortion that lifts the degeneracy of two frontier orbitals. The energetic order of the levels can be controlled by Au and Ag atom
Orbital-Free Density Functional Theory for Molecular Structure Calculations
Institute of Scientific and Technical Information of China (English)
Huajie Chen; Aihui Zhou
2008-01-01
We give here an overview of the orbital-free density functional theory that is used for modeling atoms and molecules. We review typical approximations to the kinetic energy, exchange-correlation corrections to the kinetic and Hartree energies, and constructions of the pseudopotentials. We discuss numerical discretizations for the orbital-free methods and include several numerical results for illustrations.
Scattering of electrons from neon atoms
Dasgupta, A.; Bhatia, A. K.
1984-01-01
Scattering of electrons from neon atoms is investigated by the polarized-orbital method. The perturbed orbitals calculated with use of the Sternheimer approximation lead to the polarizability 2.803 a(0)-cube in fairly good agreement with the experimental value 2.66 a(0)-cube. Phase shifts for various partial waves are calculated in the exchange, exchange-adiabatic, and polarized-orbital approximations. They are compared with the previous results. The calculated elastic differential, total, and momentum-transfer cross sections are compared with the experimental results. The polarized-orbital approximation yields results which show general improvement over the exchange-adiabatic approximation.
Physics of higher orbital bands in optical lattices: a review
Li, Xiaopeng; Liu, W. Vincent
2015-01-01
Orbital degree of freedom plays a fundamental role in understanding the unconventional properties in solid state materials. Experimental progress in quantum atomic gases has demonstrated that high orbitals in optical lattices can be used to construct quantum emulators of exotic models beyond natural crystals, where novel many-body states such as complex Bose-Einstein condensation and topological semimetals emerge. A brief introduction of orbital degree of freedom in optical lattices is given ...
Institute of Scientific and Technical Information of China (English)
陈兰芳
2016-01-01
The single-electron, two-centre atomic orbital close-coupling method is adopted to calculate elec-tron-loss cross sections of H(2s) in H(1s) + H(2s) collisions. The theoretical results are compared with experimental data. Our studies have shown that the electron-loss cross sections of H(2s) in H(1s) + H(2s) collisions calculated by the single-electron, two-centre atomic orbital close-coupling method are in reasona-ble agreement with experimental data. The ionization and de-excitation cross sections of H(2s), and the cap-ture cross sections of H(1s) in H(1s) + H(2s) collisions are also presented.%采用单电子的双中心原子轨道强耦合方法，计算了H(1s)+H(2s)碰撞体系H(2s)失去电子过程的总截面，并与前人的实验结果进行了比较。研究表明，采用双中心原子轨道强耦合方法得到的H(1s)+H(2s)体系H(2s)失去电子过程的截面与实验比较符合。同时，还给出了H(1s)+H(2s)碰撞体系H (2s)电离过程、H(1s)俘获电子过程和H(2s)退激发到H(1s)过程的理论截面。
The hybrid opacity code SCO-RCG: recent developments
Pain, Jean-Christophe; Porcherot, Quentin; Blenski, Thomas
2013-01-01
Absorption and emission spectra of multicharged-ion plasmas contain a huge number of electron configurations and electric-dipolar lines, which can be handled by global methods. However, some transition arrays consist only of a small bunch of lines. For that reason, we developed the hybrid opacity code SCO-RCG combining the (statistical) super-transition-array method and the (detailed) fine-structure calculation (requiring the diagonalization of the Hamiltonian matrix) of atomic structure. In order to decide whether a detailed treatment of lines is necessary and to determine the validity of statistical methods, the code involves criteria taking into account coalescence of lines and porosity (localized absence of lines) in transition arrays. Data required for the calculation of detailed transition arrays (Slater, spin-orbit and dipolar integrals) are provided by the super-configuration code SCO, which takes into account plasma screening effects on wavefunctions. Then, level energies and lines are calculated by ...
Correlation effects and orbital magnetism of Co clusters
Di Marco, L Peters I; Şaşıoğlu, E; Altun, A; Rossen, S; Friedrich, C; Blügel, S; Katsnelson, M I; Kirilyuk, A; Eriksson, O
2016-01-01
Recent experiments on isolated Co clusters have shown huge orbital magnetic moments in comparison with their bulk and surface counterparts. These clusters hence provide the unique possibility to study the evolution of the orbital magnetic moment with respect to the cluster size and how competing interactions contribute to the quenching of orbital magnetism. We investigate here different theoretical methods to calculate the spin and orbital moments of Co clusters, and assess the performances of the methods in comparison with experiments. It is shown that density functional theory in conventional local density or generalized gradient approximations, or even with a hybrid functional, severely underestimates the orbital moment. As natural extensions/corrections we considered the orbital polarization correction, the LDA+U approximation as well as the LDA+DMFT method. Our theory shows that of the considered methods, only the LDA+DMFT method provides orbital moments in agreement with experiment, thus emphasizing the...
Low-Earth Orbit Determination from Gravity Gradient Measurements
Sun, Xiucong; Macabiau, Christophe; Han, Chao
2016-01-01
An innovative orbit determination method which makes use of gravity gradients for Low-Earth-Orbiting satellites is proposed. The measurement principle of gravity gradiometry is briefly reviewed and the sources of measurement error are analyzed. An adaptive hybrid least squares batch filter based on linearization of the orbital equation and unscented transformation of the measurement equation is developed to estimate the orbital states and the measurement biases. The algorithm is tested with the actual flight data from the European Space Agency Gravity field and steady-state Ocean Circulation Explorer. The orbit determination results are compared with the GPS-derived orbits. The radial and cross-track position errors are on the order of tens of meters, whereas the along-track position error is over one order of magnitude larger. The gravity gradient based orbit determination method is promising for potential use in GPS-denied spacecraft navigation.
Electronic and magnetic properties of 1T-HfS2 by doping transition-metal atoms
Zhao, Xu; Wang, Tianxing; Wang, Guangtao; Dai, Xianqi; Xia, Congxin; Yang, Lin
2016-10-01
We explored the electronic and magnetic properties of 1T-HfS2 doped by transition metal (TM) atom using the first-principles calculation. We doped the transition metal atoms from the IIIB to VIB groups in nonmagnetic 1T-HfS2. Numerical results show that the pristine 1T-HfS2 is a semiconductor with indirect gaps of 1.250 eV. Magnetism can be observed for V, Cr, Mn, Fe, Co, and Cu doping. The polarized charges mainly arise from the localized 3d electrons of the TM atom. The strong p-d hybridization was found between the 3d orbitals of TM and 3p orbitals of S. The substituted 1T-HfS2 can be a metal, semiconductor or half-metal. Analysis of the band structure and magnetic properties indicates that TM-doped HfS2 (TM = V, Fe, Cu) are promising systems to explore two-dimensional diluted magnetic semiconductors. The formation energy calculations also indicate that it is energetically favorable and relatively easier to incorporate transition metal atom into the HfS2 under S-rich experimental conditions. In contrast, V-doped HfS2 has relatively wide half-metallic gap and low formation energy. So V-doped 1T-HfS2 is ideal for spin injection, which is important for application in semiconductor spintronics.
Two-component hybrid time-dependent density functional theory within the Tamm-Dancoff approximation
Energy Technology Data Exchange (ETDEWEB)
Kühn, Michael [Institut für Physikalische Chemie, Karlsruher Institut für Technologie, Kaiserstraße 12, 76131 Karlsruhe (Germany); Weigend, Florian, E-mail: florian.weigend@kit.edu [Institut für Physikalische Chemie, Karlsruher Institut für Technologie, Kaiserstraße 12, 76131 Karlsruhe (Germany); Institut für Nanotechnologie, Karlsruher Institut für Technologie, Postfach 3640, 76021 Karlsruhe (Germany)
2015-01-21
We report the implementation of a two-component variant of time-dependent density functional theory (TDDFT) for hybrid functionals that accounts for spin-orbit effects within the Tamm-Dancoff approximation (TDA) for closed-shell systems. The influence of the admixture of Hartree-Fock exchange on excitation energies is investigated for several atoms and diatomic molecules by comparison to numbers for pure density functionals obtained previously [M. Kühn and F. Weigend, J. Chem. Theory Comput. 9, 5341 (2013)]. It is further related to changes upon switching to the local density approximation or using the full TDDFT formalism instead of TDA. Efficiency is demonstrated for a comparably large system, Ir(ppy){sub 3} (61 atoms, 1501 basis functions, lowest 10 excited states), which is a prototype molecule for organic light-emitting diodes, due to its “spin-forbidden” triplet-singlet transition.
Hanke, J.-P.; Freimuth, F.; Nandy, A. K.; Zhang, H.; Blügel, S.; Mokrousov, Y.
2016-09-01
We address the importance of the modern theory of orbital magnetization for spintronics. Based on an all-electron first-principles approach, we demonstrate that the predictive power of the routinely employed "atom-centered" approximation is limited to materials like elemental bulk ferromagnets, while the application of the modern theory of orbital magnetization is crucial in chemically or structurally inhomogeneous systems such as magnetic thin films, and materials exhibiting nontrivial topology in reciprocal and real space, e.g., Chern insulators or noncollinear systems. We find that the modern theory is particularly crucial for describing magnetism in a class of materials that we suggest here—topological orbital ferromagnets.
Spin and orbital moments in actinide compounds
DEFF Research Database (Denmark)
Lebech, B.; Wulff, M.; Lander, G.H.
1991-01-01
experiments designed to determine the magnetic moments at the actinide and transition-metal sublattice sites in compounds such as UFe2, NpCo2, and PuFe2 and to separate the spin and orbital components at the actinide sites. The results show, indeed, that the ratio of the orbital to spin moment is reduced......The extended spatial distribution of both the transition-metal 3d electrons and the actinide 5f electrons results in a strong interaction between these electron states when the relevant elements are alloyed. A particular interesting feature of this hybridization, which is predicted by single...
Preseptal Cellulitis, Orbital Cellulitis, Orbital Abscess
Directory of Open Access Journals (Sweden)
Rana Altan Yaycıoğlu
2012-12-01
Full Text Available Patients with orbital infections present to our clinic usually with unilateral pain, hyperemia, and edema of the eyelids. The differentiation between preseptal and orbital cellulitis is utmost important in that the second requires hospitalization. Since in orbital cellulitis, the tissues posterior to the orbital septum are involved, signs such as conjunctival chemosis, limited eye movement, decreased vision, as well as afferent pupil defect secondary to optic nerve involvement may also be observed. Prompt intravenous antibiotic treatment should be started, and surgical drainage may be performed if patient shows failure to improve in 48 hours despite optimal management. Without treatment, the clinical course may progress to subperiosteal or orbital abscess, and even to cavernous sinus thrombosis. (Turk J Ophthalmol 2012; 42: Supplement 52-6
Energy Technology Data Exchange (ETDEWEB)
Kim, Manuela; Stripeikis, Jorge [Laboratorio de Analisis de Trazas, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, INQUIMAE, Universidad de Buenos Aires, Pabellon 2, Ciudad Universitaria, (1428) Buenos Aires (Argentina); Tudino, Mabel [Laboratorio de Analisis de Trazas, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, INQUIMAE, Universidad de Buenos Aires, Pabellon 2, Ciudad Universitaria, (1428) Buenos Aires (Argentina)], E-mail: tudino@qi.fcen.uba.ar
2009-06-15
A lab-made hybrid mesoporous solid was employed in a flow injection solid phase extraction electrothermal atomic absorption spectrometric (FI-SPE-ETAAS) system for the selective retention of Cr(VI). The solid was prepared by co-condensation of sodium tetraethylortosilicate and 3-aminopropyltriethoxysilane by sol-gel methodology and one-pot synthesis and characterized by Fourier transform infrared spectroscopy, X ray diffraction spectroscopy, and scanning electronic microscopy. Adsorption capacities at different pH values of both, Cr(VI) and Cr(III), were also measured in order to obtain the optimum retention for Cr(VI) with no interference of Cr(III). The maximum capacity of adsorption (4.35 mmol g{sup -} {sup 1}) was observed for pH values between 2-3, whilst Cr(III) was found to remain in solution (adsorption capacity = 0.007 mmol g{sup -} {sup 1}). Then, a microcolumn (bed volume: 7.9 {mu}L) was filled with the solid and inserted in the FI-ETAAS system for analytical purposes. Since the analyte was strongly retained by the filling in the anionic form, 0.1 mol L{sup -} {sup 1} hydroxylammonium chloride in 1 mol L{sup -} {sup 1} hydrochloric acid was selected as eluent due to its redox characteristics. In this way, the sorbed Cr(VI) was easily released in the cationic form. The enrichment factor (EF) was found as a compromise between sensitivity and sample throughput and a value of 27 was obtained under optimized conditions: pH 2, sample loading 2 mL min{sup -} {sup 1} (60 s), elution flow rate 0.5 ml min{sup -} {sup 1} (eluent volume: 75 {mu}L). Under optimized conditions the limit of detection for Cr(VI) was 1.2 ng L{sup -} {sup 1}, the precision, expressed as RSD was 2.5%, the sample throughput 21/h, and the microcolumn lifetime was over 300 adsorption/desorption cycles. Cr(III) determination was also performed by simply measuring its concentration at the end of the column and after Cr(VI) retention by the mesoporous solid. Applications of the methodology to
Imaging the Temporal Evolution of Molecular Orbitals during Ultrafast Dissociation
Sann, H.; Havermeier, T.; Müller, C.; Kim, H.-K.; Trinter, F.; Waitz, M.; Voigtsberger, J.; Sturm, F.; Bauer, T.; Wallauer, R.; Schneider, D.; Weller, M.; Goihl, C.; Tross, J.; Cole, K.; Wu, J.; Schöffler, M. S.; Schmidt-Böcking, H.; Jahnke, T.; Simon, M.; Dörner, R.
2016-12-01
We investigate the temporal evolution of molecular frame angular distributions of Auger electrons emitted during ultrafast dissociation of HCl following a resonant single-photon excitation. The electron emission pattern changes its shape from that of a molecular σ orbital to that of an atomic p state as the system evolves from a molecule into two separated atoms.
Wilson, David B.
1981-01-01
Surveys the research of scientists like Joule, Kelvin, Maxwell, Clausius, and Boltzmann as it comments on the basic conceptual issues involved in the development of a more precise kinetic theory and the idea of a kinetic atom. (Author/SK)
Spin-polarized exciton quantum beating in hybrid organic-inorganic perovskites
Odenthal, Patrick; Talmadge, William; Gundlach, Nathan; Wang, Ruizhi; Zhang, Chuang; Sun, Dali; Yu, Zhi-Gang; Valy Vardeny, Z.; Li, Yan S.
2017-09-01
Hybrid organic-inorganic perovskites have emerged as a new class of semiconductors that exhibit excellent performance as active layers in photovoltaic solar cells. These compounds are also highly promising materials for the field of spintronics due to their large and tunable spin-orbit coupling, spin-dependent optical selection rules, and their predicted electrically tunable Rashba spin splitting. Here we demonstrate the optical orientation of excitons and optical detection of spin-polarized exciton quantum beating in polycrystalline films of the hybrid perovskite CH3NH3PbClxI3-x. Time-resolved Faraday rotation measurement in zero magnetic field reveals unexpectedly long spin lifetimes exceeding 1 ns at 4 K, despite the large spin-orbit couplings of the heavy lead and iodine atoms. The quantum beating of exciton states in transverse magnetic fields shows two distinct frequencies, corresponding to two g-factors of 2.63 and -0.33, which we assign to electrons and holes, respectively. These results provide a basic picture of the exciton states in hybrid perovskites, and suggest they hold potential for spintronic applications.
Spin-Orbit Coupling and Spin Textures in Optical Superlattices
Li, Junru; Shteynas, Boris; Burchesky, Sean; Top, Furkan Cagri; Su, Edward; Lee, Jeongwon; Jamison, Alan O; Ketterle, Wolfgang
2016-01-01
We proposed and demonstrated a new approach for realizing spin orbit coupling with ultracold atoms. We use orbital levels in a double well potential as pseudospin states. Two-photon Raman transitions between left and right wells induce spin-orbit coupling. This scheme does not require near resonant light, features adjustable interactions by shaping the double well potential, and does not depend on special properties of the atoms. A pseudospinor Bose-Einstein condensate spontaneously acquires an antiferromagnetic pseudospin texture which breaks the lattice symmetry similar to a supersolid.
Energy Technology Data Exchange (ETDEWEB)
West, J.G.W. [Electrical Machines (United Kingdom)
1997-07-01
The reasons for adopting hybrid vehicles result mainly from the lack of adequate range from electric vehicles at an acceptable cost. Hybrids can offer significant improvements in emissions and fuel economy. Series and parallel hybrids are compared. A combination of series and parallel operation would be the ideal. This can be obtained using a planetary gearbox as a power split device allowing a small generator to transfer power to the propulsion motor giving the effect of a CVT. It allows the engine to run at semi-constant speed giving better fuel economy and reduced emissions. Hybrid car developments are described that show the wide range of possible hybrid systems. (author)
National Aeronautics and Space Administration — The Lunar Orbiter Photo Gallery is an extensive collection of over 2,600 high- and moderate-resolution photographs produced by all five of the Lunar Orbiter...
DEFF Research Database (Denmark)
Riis, Troels; Jørgensen, John Leif
1999-01-01
This documents describes a test of the implementation of the ASC orbit model for the Champ satellite.......This documents describes a test of the implementation of the ASC orbit model for the Champ satellite....
Don, Henk
2011-01-01
We study the geometry of billiard orbits on rectangular billiards. A truncated billiard orbit induces a partition of the rectangle into polygons. We prove that thirteen is a sharp upper bound for the number of different areas of these polygons.
Traumatic transconjunctival orbital emphysema.
Stroh, E M; Finger, P T
1990-01-01
Orbital emphysema can be produced by trans-conjunctival migration of air from a high pressure airgun. In an industrial accident an 8 mm conjunctival laceration was produced in the superior fornix which acted as a portal of entry for air into the subconjunctival, subcutaneous, and retrobulbar spaces. Computed tomography revealed no evidence of orbital fracture and showed that traumatic orbital emphysema occurred without a broken orbital bone.
Electric field sensing near the surface microstructure of an atom chip using cold Rydberg atoms
Carter, J D; Martin, J D D
2012-01-01
The electric fields near the heterogeneous metal/dielectric surface of an atom chip were measured using cold atoms. The atomic sensitivity to electric fields was enhanced by exciting the atoms to Rydberg states that are 10^8 times more polarizable than the ground state. We attribute the measured fields to charging of the insulators between the atom chip wires. Surprisingly, it is observed that these fields may be dramatically lowered with appropriate voltage biasing, suggesting configurations for the future development of hybrid quantum systems.
The many faces of the Bohr atom
Kragh, Helge
2013-01-01
The atomic model that Niels Bohr suggested in 1913 celebrated its greatest victories in connection with one-electron atoms. Among them were the isotopic spectral effect and what became known as Rydberg atoms, insights that were fully recognized only many years later. He considered the original ring model a first step towards an understanding of atomic structure, and during the following years he developed it into more ambitious models that, he hoped, would also describe many-electron atoms. His theory of the periodic system marked the culmination of the orbital atom within the framework of the old quantum theory. However, the theory would soon be replaced by more symbolic models that heralded the coming of the quantum-mechanical atom.
Introducing Earth's Orbital Eccentricity
Oostra, Benjamin
2015-01-01
Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…
Long-Range Corrected Hybrid Density Functionals with Improved Dispersion Corrections
Lin, You-Sheng; Mao, Shan-Ping; Chai, Jeng-Da
2012-01-01
By incorporating the improved empirical atom-atom dispersion corrections from DFT-D3 [Grimme, S.; Antony, J.; Ehrlich, S.; Krieg, H. J. Chem. Phys. 2010, 132, 154104], two long-range corrected (LC) hybrid density functionals are proposed. Our resulting LC hybrid functionals, omegaM06-D3 and omegaB97X-D3, are shown to be accurate for a very wide range of applications, such as thermochemistry, kinetics, noncovalent interactions, frontier orbital energies, fundamental gaps, and long-range charge-transfer excitations, when compared with common global and LC hybrid functionals. Relative to omegaB97X-D [Chai, J.-D.; Head-Gordon, M. Phys. Chem. Chem. Phys. 2008, 10, 6615], omegaB97X-D3 (reoptimization of omegaB97X-D with improved dispersion corrections) is shown to be superior for non-bonded interactions, and similar in performance for bonded interactions, while omegaM06-D3 is shown to be superior for general applications.
Atoms in static fields Chaos or Diffraction?
Dando, P A
1998-01-01
A brief review of the manifestations of classical chaos observed in atomic systems is presented. Particular attention is paid to the analysis of atomic spectra by periodic orbit-type theories. For diamagnetic non-hydrogenic Rydberg atoms, the dynamical explanation for observed spectral features has been disputed. By building on our previous work on the photoabsorption spectrum, we show how, by the addition of diffractive terms, the spectral fluctuations in the energy level spectrum of general Rydberg atoms can be obtained with remarkable precision from the Gutzwiller trace formula. This provides further evidence that non-hydrogenic systems are most naturally described in terms of diffraction rather than classical chaos.
Ri, Gum-Chol; Yu, Chol-Jun; Kim, Jin-Song; Hong, Song-Nam; Jong, Un-Gi; Ri, Mun-Hyok
2016-08-01
First-principles calculations were carried out to investigate the structural, energetic, and electronic properties of ternary graphite compounds cointercalated with alkali atoms (AM = Li, Na, and K) and normal alkylamine molecules (nCx; x = 1, 2, 3, 4), denoted as AM-nCx-GICs. From the optimization of the orthorhombic unit cells for the crystalline compounds, it was found that, with the increase in the atomic number of alkali atoms, the layer separations decrease in contrast to AM-GICs, while the bond lengths between alkali atoms and graphene layer, and nitrogen atom of alkylamine increase. The calculated formation energies and interlayer binding energies of AM-nC3-GICs indicate that the compounds is increasingly stabilized from Li to K, and the energy barriers for migration of alkali atoms suggest that alkali cation with larger ionic radius diffuses more smoothly in graphite, being similar to AM-GICs. Through the analysis of electronic properties, it was established that more extent of electronic charge is transferred from more electropositive alkali atom to the carbon ring of graphene layer, and the hybridization of valence electron orbitals between alkylamine molecules and graphene layer is occurred.
The nature of excess electrons in anatase and rutile from hybrid DFT and RPA.
Spreafico, Clelia; VandeVondele, Joost
2014-12-21
The behavior of excess electrons in undoped and defect free bulk anatase and rutile TiO2 has been investigated by state-of-the-art electronic structure methods including hybrid density functional theory (DFT) and the random phase approximation (RPA). Consistent with experiment, charge trapping and polaron formation is observed in both anatase and rutile. The difference in the anisotropic shape of the polarons is characterized, confirming for anatase the large polaron picture. For anatase, where polaron formation energies are small, charge trapping is observed also with standard hybrid functionals, provided the simulation cell is sufficiently large (864 atoms) to accommodate the lattice relaxation. Even though hybrid orbitals are required as a starting point for RPA in this system, the obtained polaron formation energies are relatively insensitive to the amount of Hartree-Fock exchange employed. The difference in trapping energy between rutile and anatase can be obtained accurately with both hybrid functionals and RPA. Computed activation energies for polaron hopping and delocalization clearly show that anatase and rutile might have different charge transport mechanisms. In rutile, only hopping is likely, whereas in anatase hopping and delocalization are competing. Delocalization will result in conduction-band-like and thus enhanced transport. Anisotropic conduction, in agreement with experimental data, is observed, and results from the tendency to delocalize in the [001] direction in rutile and the (001) plane in anatase. For future work, our calculations serve as a benchmark and suggest RPA on top on hybrid orbitals (PBE0 with 30% Hartree-Fock exchange), as a suitable method to study the rich chemistry and physics of TiO2.
Using Atom-Probe Tomography to Understand Zn O ∶Al /SiO 2/Si Schottky Diodes
Jaramillo, R.; Youssef, Amanda; Akey, Austin; Schoofs, Frank; Ramanathan, Shriram; Buonassisi, Tonio
2016-09-01
We use electronic transport and atom-probe tomography to study Zn O ∶Al /SiO 2/Si Schottky diodes on lightly doped n - and p -type Si. We vary the carrier concentration in the ZnO ∶Al films by 2 orders of magnitude, but the Schottky barrier height remains nearly constant. Atom-probe tomography shows that Al segregates to the interface, so that the ZnO ∶Al at the junction is likely to be metallic even when the bulk of the ZnO ∶Al film is semiconducting. We hypothesize that the observed Fermi-level pinning is connected to the insulator-metal transition in doped ZnO. This implies that tuning the band alignment at oxide/Si interfaces may be achieved by controlling the transition between localized and extended states in the oxide, thereby changing the orbital hybridization across the interface.
Is the magnetic anisotropy proportional to the orbital moment?
Energy Technology Data Exchange (ETDEWEB)
Skomski, R; Kashyap, A; Enders, A
2011-04-01
The relation between orbital moment and magnetic anisotropy is investigated by model calculations, which show that only a part of the spin-orbit coupling contributes to the anisotropy. A large part of the anisotropy energy, about 50% for iron series elements and nearly 100% for rare-earths, is stored in the nonrelativistic part of the Hamiltonian. A feature important for x-ray magnetic circular dichroism is that the orbital moment of heavy atoms rotates with the spin moment, whereas in light atoms, the orbital moment is recreated in each different direction. In the discussion, we consider three examples of current interest in different areas of magnetism, namely, spin-orbit coupling in Gd3+ and Eu2+, surface anisotropy of Nd2Fe14B, and multiferroic magnetization switching using rare-earths. (C) 2011 American Institute of Physics. [doi:10.1063/1.3562445
Illustrating Concepts in Physical Organic Chemistry with 3D Printed Orbitals
Robertson, Michael J.; Jorgensen, William L.
2015-01-01
Orbital theory provides a powerful tool for rationalizing and understanding many phenomena in chemistry. In most introductory chemistry courses, students are introduced to atomic and molecular orbitals in the form of two-dimensional drawings. In this work, we describe a general method for producing 3D printing files of orbital models that can be…
Conduction of molecular electronic devices: Qualitative insights through atom-atom polarizabilities
Energy Technology Data Exchange (ETDEWEB)
Stuyver, T.; Fias, S., E-mail: sfias@vub.ac.be; De Proft, F.; Geerlings, P. [ALGC, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel (Belgium); Fowler, P. W. [Department of Chemistry, University of Sheffield, Sheffield S3 7HF (United Kingdom)
2015-03-07
The atom-atom polarizability and the transmission probability at the Fermi level, as obtained through the source-and-sink-potential method for every possible configuration of contacts simultaneously, are compared for polycyclic aromatic compounds. This comparison leads to the conjecture that a positive atom-atom polarizability is a necessary condition for transmission to take place in alternant hydrocarbons without non-bonding orbitals and that the relative transmission probability for different configurations of the contacts can be predicted by analyzing the corresponding atom-atom polarizability. A theoretical link between the two considered properties is derived, leading to a mathematical explanation for the observed trends for transmission based on the atom-atom polarizability.
Conduction of molecular electronic devices: qualitative insights through atom-atom polarizabilities.
Stuyver, T; Fias, S; De Proft, F; Fowler, P W; Geerlings, P
2015-03-07
The atom-atom polarizability and the transmission probability at the Fermi level, as obtained through the source-and-sink-potential method for every possible configuration of contacts simultaneously, are compared for polycyclic aromatic compounds. This comparison leads to the conjecture that a positive atom-atom polarizability is a necessary condition for transmission to take place in alternant hydrocarbons without non-bonding orbitals and that the relative transmission probability for different configurations of the contacts can be predicted by analyzing the corresponding atom-atom polarizability. A theoretical link between the two considered properties is derived, leading to a mathematical explanation for the observed trends for transmission based on the atom-atom polarizability.
Dean, David L.
1995-01-01
McDonnell Douglas Aerospace, as part of its Independent R&D, has initiated development of a clean burning, high performance hybrid fuel for consideration as an alternative to the solid rocket thrust augmentation currently utilized by American space launch systems including Atlas, Delta, Pegasus, Space Shuttle, and Titan. It could also be used in single stage to orbit or as the only propulsion system in a new launch vehicle. Compared to solid propellants based on aluminum and ammonium perchlorate, this fuel is more environmentally benign in that it totally eliminates hydrogen chloride and aluminum oxide by products, producing only water, hydrogen, nitrogen, carbon oxides, and trace amounts of nitrogen oxides. Compared to other hybrid fuel formulations under development, this fuel is cheaper, denser, and faster burning. The specific impulse of this fuel is comparable to other hybrid fuels and is between that of solids and liquids. The fuel also requires less oxygen than similar hybrid fuels to produce maximum specific impulse, thus reducing oxygen delivery system requirements.
Physics of higher orbital bands in optical lattices: a review
Li, Xiaopeng; Liu, W. Vincent
2016-11-01
The orbital degree of freedom plays a fundamental role in understanding the unconventional properties in solid state materials. Experimental progress in quantum atomic gases has demonstrated that high orbitals in optical lattices can be used to construct quantum emulators of exotic models beyond natural crystals, where novel many-body states such as complex Bose-Einstein condensates and topological semimetals emerge. A brief introduction of orbital degrees of freedom in optical lattices is given and a summary of exotic orbital models and resulting many-body phases is provided. Experimental consequences of the novel phases are also discussed.
Directory of Open Access Journals (Sweden)
Rahul T Chakor
2012-01-01
Full Text Available Idiopathic orbital inflammation is the third most common orbital disease, following Graves orbitopathy and lymphoproliferative diseases. We present a 11 year old girl with 15 days history of painless diplopia. There was no history of fluctuation of symptoms, drooping of eye lids or diminished vision. She had near total restricted extra-ocular movements and mild proptosis of the right eye. There was no conjunctival injection, chemosis, or bulb pain. There was no eyelid retraction or lid lag. Rest of the neurological examination was unremarkable.Erythrocyte sedimentation rate was raised with eosinophilia. Antinuclear antibodies were positive. Liver, renal and thyroid functions were normal. Antithyroid, double stranded deoxyribonucleic acid and acetylcholine receptor antibodies were negative. Repetitive nerve stimulation was negative. Magnetic resonance imaging (MRI of the orbit was typical of orbital myositis. The patient responded to oral steroids. Orbital myositis can present as painless diplopia. MRI of orbit is diagnostic in orbital myositis.
Directory of Open Access Journals (Sweden)
Jeffrey M Joseph
2011-01-01
Full Text Available Jeffrey M Joseph, Ioannis P GlavasDivision of Ophthalmic Plastic and Reconstructive Surgery, Department of Ophthalmology, School of Medicine, New York University, New York, NY, USA; Manhattan Eye, Ear, and Throat Hospital, New York, NY, USAAbstract: This review of orbital fractures has three goals: 1 to understand the clinically relevant orbital anatomy with regard to periorbital trauma and orbital fractures, 2 to explain how to assess and examine a patient after periorbital trauma, and 3 to understand the medical and surgical management of orbital fractures. The article aims to summarize the evaluation and management of commonly encountered orbital fractures from the ophthalmologic perspective and to provide an overview for all practicing ophthalmologists and ophthalmologists in training.Keywords: orbit, trauma, fracture, orbital floor, medial wall, zygomatic, zygomatic complex, zmc fracture, zygomaticomaxillary complex fractures
Theoretical Calculation of Absolute Radii of Atoms and Ions. Part 1. The Atomic Radii
Directory of Open Access Journals (Sweden)
Raka Biswas
2002-02-01
Full Text Available Abstract. A set of theoretical atomic radii corresponding to the principal maximum in the radial distribution function, 4ÃÂ€r2R2 for the outermost orbital has been calculated for the ground state of 103 elements of the periodic table using Slater orbitals. The set of theoretical radii are found to reproduce the periodic law and the Lother MeyerÃ¢Â€Â™s atomic volume curve and reproduce the expected vertical and horizontal trend of variation in atomic size in the periodic table. The d-block and f-block contractions are distinct in the calculated sizes. The computed sizes qualitatively correlate with the absolute size dependent properties like ionization potentials and electronegativity of elements. The radii are used to calculate a number of size dependent periodic physical properties of isolated atoms viz., the diamagnetic part of the atomic susceptibility, atomic polarizability and the chemical hardness. The calculated global hardness and atomic polarizability of a number of atoms are found to be close to the available experimental values and the profiles of the physical properties computed in terms of the theoretical atomic radii exhibit their inherent periodicity. A simple method of computing the absolute size of atoms has been explored and a large body of known material has been brought together to reveal how many different properties correlate with atomic size.
Adsorption of rare-earth atoms onl silicon carbide nanotube: a density-functional study
An, Zhiwei; Shen, Jiang
2014-07-01
In this paper, we investigate the adsorption of a series of rare-earth (RE) metal atoms (La, Pr, Nd, Sm and Eu) on the pristine zigzag (8, 0) silicon carbide nanotube (SiCNT) using density functional theory (DFT). Main focuses are placed on the stable adsorption sites, the corresponding binding energies, and the modified electronic properties of the SiC nanotubes due to the adsorbates. A single RE atom prefers to adsorb strongly at the hollow site with relatively high binding energy (larger than 1.0 eV). Due to the rolling effect of single-walled SiCNTs, the inside configurations are more stable than the outside ones. For RE-adsorbed systems, the adsorption of metal atoms induces certain impurity states within the band gap of the pristine SiCNT. Furthermore, we analyze there exists hybridizations between RE-5d, 6s, C-2p and Si-3p orbitals for the RE atom adsorption on the SiCNTs.
Local random phase approximation with projected oscillator orbitals
Mussard, Bastien
2015-01-01
An approximation to the many-body London dispersion energy in molecular systems is expressed as a functional of the occupied orbitals only. The method is based on the local-RPA theory. The occupied orbitals are localized molecular orbitals and the virtual space is described by projected oscillator orbitals, i.e. functions obtained by multiplying occupied localized orbitals with solid spherical harmonic polynomials having their origin at the orbital centroids. Since we are interested in the long-range part of the correlation energy, responsible for dispersion forces, the electron repulsion is approximated by its multipolar expansion. This procedure leads to a fully non-empirical long-range correlation energy expression. Molecular dispersion coefficients calculated from determinant wave functions obtained by a range-separated hybrid method reproduce experimental values with less than 15% error.
Loring, FH
2014-01-01
Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec
Adiabatic geometric phases in hydrogenlike atoms
Sjöqvist, Erik; Yi, X. X.; Åberg, J.
2005-01-01
We examine the effect of spin-orbit coupling on geometric phases in hydrogenlike atoms exposed to a slowly varying magnetic field. The marginal geometric phases associated with the orbital angular momentum and the intrinsic spin fulfill a sum rule that explicitly relates them to the corresponding geometric phase of the whole system. The marginal geometric phases in the Zeeman and Paschen-Back limit are analyzed. We point out the existence of nodal points in the marginal phases that may be det...
Yoosefian, Mehdi; Etminan, Nazanin
2016-07-01
In order to explore a new novel L-amino acid/transition metal doped single walled carbon nanotube based biosensor, density functional theory calculations were studied. These hybrid structures of organic-inorganic nanobiosensors are able to detect the smallest amino acid building block of proteins. The configurations of amine and carbonyl group coordination of tryptophan aromatic amino acid adsorbed on Pd/doped single walled carbon nanotube were compared. The frontier molecular orbital theory, quantum theory atom in molecule and natural bond orbital analysis were performed. The molecular electrostatic potential and the electron density surfaces were constructed. The calculations indicated that the Pd/SWCNT was sensitive to tryptophan suggesting the importance of interaction with biological molecule and potential detecting application. The proposed nanobiosensor represents a highly sensitive detection of protein at ultra-low concentration in diagnosis applications.
Dubillard, S; Rota, J-B; Saue, T; Faegri, K
2006-04-21
We report the implementation of Pipek-Mezey [J. Chem. Phys. 90, 4916 (1989)] localization of molecular orbitals in the framework of a four-component relativistic molecular electronic structure theory. We have used an exponential parametrization of orbital rotations which allows the use of unconstrained optimization techniques. We demonstrate the strong basis set dependence of the Pipek-Mezey localization criterion and how it can be eliminated. We have employed localization in conjunction with projection analysis to study the bonding in the water molecule and its heavy homologues. We demonstrate that in localized orbitals the repulsion between hydrogens in the water molecule is dominated by electrostatic rather than exchange interactions and that freezing the oxygen 2s orbital blocks polarization of this orbital rather than hybridization. We also point out that the bond angle of the water molecule cannot be rationalized from the potential energy alone due to the force term of the molecular virial theorem that comes into play at nonequilibrium geometries and which turns out to be crucial in order to correctly reproduce the minimum of the total energy surface. In order to rapidly assess the possible relativistic effects we have carried out the geometry optimizations of the water molecule at various reduced speed of light with and without spin-orbit interaction. At intermediate speeds, the bond angle is reduced to around 90 degrees , as is known experimentally for H(2)S and heavier homologues, although our model of ultrarelativistic water by construction does not allow any contribution from d orbitals to bonding. At low speeds of light the water molecule becomes linear which is in apparent agreement with the valence shell electron pair repulsion (VSEPR) model since the oxygen 2s12 and 2p12 orbitals both become chemically inert. However, we show that linearity is brought about by the relativistic stabilization of the (n + 1)s orbital, the same mechanism that leads to an
Orbital selective Mott transition in 3D and 5F materials
Toropova, Antonina
We study two types of strongly correlated electron systems in the example of the transition oxide CrO2 and actinide series. We found that the physics of both types of materials can be interpreted and discussed using concept of orbital selective Mott transition (OSMT). The theory of OSMT is discussed in framework of the multiorbital Hubbard model applied to the description of t2g orbitals of Cr atoms in chromium dioxide as well as in the framework of a more generalized model for 5f materials containing both Hubbard-like and Anderson-like contributions. The electronic structure, transport, and magnetic properties of selected compounds are investigated by means of Ab Initio calculations. The many body techniques such as LDA+U and dynamical mean field theory (DMFT) have been used in addition to density functional based local density approximation (LDA) method. The half-metallic ferromagnet CrO2 has been shown to demonstrate effectively weakly correlated behavior in ordered state due to big exchange splitting within t2g orbitals. The detailed DMFT study with Quantum Monte Carlo (QMC) impurity solver revealed that in the paramagnetic state this compound was on the edge of a quantum transition. In the case of the actinide series we first demonstrated the choice of basis which optimum for DMFT based calculations. By means of detailed one-electron band structure analysis we showed that hybridization term of 5f-orbitals with conduction electrons must be included in the actinide Hamiltonian due to permanent presence of uncorrelated states at Fermi level. We conclude study of 5f-materials presenting tight-binding parametrization and exploring magnetic characteristics.
Wright, Jason T; Marcy, Geoffrey W; Han, Eunkyu; Feng, Ying; Johnson, John Asher; Howard, Andrew W; Valenti, Jeff A; Anderson, Jay; Piskunov, Nikolai
2010-01-01
We present a database of well determined orbital parameters of exoplanets. This database comprises spectroscopic orbital elements measured for 421 planets orbiting 357 stars from radial velocity and transit measurements as reported in the literature. We have also compiled fundamental transit parameters, stellar parameters, and the method used for the planets discovery. This Exoplanet Orbit Database includes all planets with robust, well measured orbital parameters reported in peer-reviewed articles. The database is available in a searchable, filterable, and sortable form on the Web at http://exoplanets.org through the Exoplanets Data Explorer Table, and the data can be plotted and explored through the Exoplanets Data Explorer Plotter. We use the Data Explorer to generate publication-ready plots giving three examples of the signatures of exoplanet migration and dynamical evolution: We illustrate the character of the apparent correlation between mass and period in exoplanet orbits, the selection different biase...
Li, Yan; Zhang, Guiqiu; Chen, Dezhan
2012-02-01
Recently, Rizzato et al. [Angew. Chem. Int. Ed. 49, 7440 (2010)] [1] reported a hydrogen-bonding-like interaction between a water molecule and a d8 metal ion (PtII) based on neutron diffraction, and provided the first crystallographic evidence for this interaction. We studied the hydrogen bonding of the O-H ... Pt interaction theoretically using atoms in molecule (AIM) and natural bond orbital analysis (NBO) in the crystallographic geometries. The method used density functional theory (DFT) with the hybrid B3LYP function. For platinum atoms, we used the Los Alamos National Laboratory 2-Double-Zeta (LANL2DZ) basis set, and for the other atoms we used 6-311++G(d,p) basis sets. Criteria based on a topological analysis of the electron density were used in order to characterize the nature of interactions in the complexes. The main purpose of the present work is to provide an answer to the following questions: Why can a filled d orbital of square-planar d8 metal ions such as platinum(II) also act as hydrogen-bond acceptors? Can a study based on the electron charge density answer this question? A good correlation between the density at the intermolecular bond critical point and the energy interaction was found. The interaction is mainly closed-shell and there is some charge transfer in this system.
Fihey, Arnaud; Kloss, Benedikt; Perrier, Aurélie; Maurel, François
2014-07-01
We present a theoretical study of Aun-dithienylethene hybrid systems (n = 3, 19, 25), where the organic molecule is covalently linked to a nanometer-scaled gold nanoparticle (NP). We aim at gaining insights on the optical properties of such photochromic devices and proposing a size-limited gold aggregate model able to recover the optical properties of the experimental system. We thus present a DFT-based calculation scheme to model the ground-state (conformation, energetic parameters) and excited-state properties (UV-visible absorption spectra) of this type of hybrid systems. Within this framework, the structural parameters (adsorption site, orientation, and internal structure of the photochrome) are found to be slightly dependent on the size/shape of the gold aggregate. The influence of the gold fragment on the optical properties of the resulting hybrid system is then discussed with the help of TD-DFT combined with an analysis of the virtual orbitals involved in the photochromic transitions. We show that, for the open hybrid isomer, the number of gold atoms is the key parameter to recover the photoactive properties that are experimentally observed. On the contrary, for hybrid closed systems, the three-dimensional structure of the metallic aggregate is of high impact. We thus conclude that Au25 corresponds to the most appropriate fragment to model nanometer-sized NP-DTE hybrid device.
Flight Testing of Hybrid Powered Vehicles
Story, George; Arves, Joe
2006-01-01
Hybrid Rocket powered vehicles have had a limited number of flights. Most recently in 2004, Scaled Composites had a successful orbital trajectory that put a private vehicle twice to over 62 miles high, the edge of space to win the X-Prize. This endeavor man rates a hybrid system. Hybrids have also been used in a number of one time launch attempts - SET-1, HYSR, HPDP. Hybrids have also been developed for use and flown in target drones. This chapter discusses various flight-test programs that have been conducted, hybrid vehicles that are in development, other hybrid vehicles that have been proposed and some strap-on applications have also been examined.
Energy Technology Data Exchange (ETDEWEB)
Hu, Zi-Yu [College of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Computational Science Research Center, Beijing 100084 (China); Shao, Xiaohong, E-mail: shaoxh@mail.buct.edu.cn, E-mail: limin.liu@csrc.ac.cn [College of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Wang, Da; Liu, Li-Min, E-mail: shaoxh@mail.buct.edu.cn, E-mail: limin.liu@csrc.ac.cn [Beijing Computational Science Research Center, Beijing 100084 (China); Johnson, J. Karl [Departments of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261 (United States)
2014-08-28
First-principles calculations are performed to investigate the adsorption of hydrogen onto Li-decorated hybrid boron nitride and graphene domains of (BN){sub x}C{sub 1−x} complexes with x = 1, 0.25, 0.5, 0.75, 0, and B{sub 0.125}C{sub 0.875}. The most stable adsorption sites for the nth hydrogen molecule in the lithium-decorated (BN){sub x}C{sub 1−x} complexes are systematically discussed. The most stable adsorption sites were affected by the charge localization, and the hydrogen molecules were favorably located above the C-C bonds beside the Li atom. The results show that the nitrogen atoms in the substrate planes could increase the hybridization between the 2p orbitals of Li and the orbitals of H{sub 2}. The results revealed that the (BN){sub x}C{sub 1−x} complexes not only have good thermal stability but they also exhibit a high hydrogen storage of 8.7% because of their dehydrogenation ability.
Preseptal and orbital cellulitis
Emine Akçay; Gamze Dereli Can; Nurullah Çağıl
2014-01-01
Preseptal cellulitis (PC) is defined as an inflammation of the eyelid and surrounding skin, whereas orbital cellulitis (OC) is an inflammation of the posterior septum of the eyelid affecting the orbit and its contents. Periorbital tissues may become infected as a result of trauma (including insect bites) or primary bacteremia. Orbital cellulitis generally occurs as a complication of sinusitis. The most commonly isolated organisms are Staphylococcus aureus, Streptococcus pneumoniae, S. epid...
Orbital inflammation: Corticosteroids first.
Dagi Glass, Lora R; Freitag, Suzanne K
2016-01-01
Orbital inflammation is common, and may affect all ages and both genders. By combining a thorough history and physical examination, targeted ancillary laboratory testing and imaging, a presumptive diagnosis can often be made. Nearly all orbital inflammatory pathology can be empirically treated with corticosteroids, thus obviating the need for histopathologic diagnosis prior to initiation of therapy. In addition, corticosteroids may be effective in treating concurrent systemic disease. Unless orbital inflammation responds atypically or incompletely, patients can be spared biopsy.
Geometric orbit datum and orbit covers
Institute of Scientific and Technical Information of China (English)
LIANG; Ke(
2001-01-01
［1］Vogan, D. , Dixmier algebras, sheets and representation theory (in Actes du colloque en I' honneur de Jacques Dixmier),Progress in Math. 92, Boston: Birkhauser Verlag, 1990, 333－397.［2］McGovern, W., Dixmier Algebras and Orbit Method, Operator Algebras, Unitary Representations and Invariant Theory,Boston: Birkhauser, 1990, 397－416.［3］Liang, K. , Parabolic inductions of nilpotent geometric orbit datum, Chinese Science Bulletin (in Chinese) , 1996, 41 (23):2116－2118.［4］Vogan, D., Representations of Real Reductive Lie Groups, Boston-Basel-Stuttgart: Birkhauser, 1981.［5］Lustig, G., Spaltenstein, N., Induced unipotent class, J. London Math. Soc., 1997, 19. 41－52.［6］Collingwood, D. H. , McGovern, W. M. , Nilpotent Orbits in Semisimple Lie Algebras, New York: Van Nostremt Reinhold,1993.
Doughnut shape atom traps with arbitrary inclination
Energy Technology Data Exchange (ETDEWEB)
Rodriguez y Masegosa, R.; Moya C, H.; Chavez C, S. [INAOE, A.P. 51 y 216, 72000 Puebla (Mexico)
2006-07-01
Since the invention of magneto-optical trap (MOT), there have been several experimental and theoretical studies of the density distribution in these devices. To the best of our knowledge, only horizontal orbital traps have been observed, perpendicular to the coil axis. In this work we report the observation of distributions of trapped atoms in pure circular orbits without a nucleus whose orbital plane is tilted up to 90diam. with respect to the horizontal plane. We have used a stabilized time phase optical array in our experiments and conventional equipment used for MOT. (Author)
Natural and artificial atoms for quantum computation
Energy Technology Data Exchange (ETDEWEB)
Buluta, Iulia; Ashhab, Sahel; Nori, Franco, E-mail: fnori@riken.jp [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan)
2011-10-15
Remarkable progress towards realizing quantum computation has been achieved using natural and artificial atoms as qubits. This paper presents a brief overview of the current status of different types of qubits. On the one hand, natural atoms (such as neutral atoms and ions) have long coherence times, and could be stored in large arrays, providing ideal 'quantum memories'. On the other hand, artificial atoms (such as superconducting circuits or semiconductor quantum dots) have the advantage of custom-designed features and could be used as 'quantum processing units'. Natural and artificial atoms can be coupled with each other and can also be interfaced with photons for long-distance communications. Hybrid devices made of natural/artificial atoms and photons may provide the next-generation design for quantum computers.
Interplay of Coulomb interaction and spin-orbit coupling
Bünemann, Jörg; Linneweber, Thorben; Löw, Ute; Anders, Frithjof B.; Gebhard, Florian
2016-07-01
We employ the Gutzwiller variational approach to investigate the interplay of Coulomb interaction and spin-orbit coupling in a three-orbital Hubbard model. Already in the paramagnetic phase we find a substantial renormalization of the spin-orbit coupling that enters the effective single-particle Hamiltonian for the quasiparticles. Only close to half band-filling and for sizable Coulomb interaction do we observe clear signatures of Hund's atomic rules for spin, orbital, and total angular momentum. For a finite local Hund's rule exchange interaction we find a ferromagnetically ordered state. The spin-orbit coupling considerably reduces the size of the ordered moment, it generates a small ordered orbital moment, and it induces a magnetic anisotropy. To investigate the magnetic anisotropy energy, we use an external magnetic field that tilts the magnetic moment away from the easy axis (1 ,1 ,1 ) .
2008-01-01
This image shows the paths of three spacecraft currently in orbit around Mars, as well as the path by which NASA's Phoenix Mars Lander will approach and land on the planet. The t-shaped crosses show where the orbiters will be when Phoenix enters the atmosphere, while the x-shaped crosses show their location at landing time. All three orbiters, NASA's Mars Reconnaissance Orbiter, NASA's Mars Odyssey and the European Space Agency's Mars Express, will be monitoring Phoenix during the final steps of its journey to the Red Planet. Phoenix will land just south of Mars's north polar ice cap.
Energy Technology Data Exchange (ETDEWEB)
Goldschmidt, B.
1990-01-01
This book is a memoir of rivalries among the Allies over the bomb, by a participant and observer. Nuclear proliferation began in the uneasy wartime collaboration of the United States, England, Canada, and Free France to produce the atom bomb. Through the changes of history, a young French chemist had a role in almost every act of this international drama. This memoir is based on Goldschmidt's own recollections, interviews with other leading figures, and 3,000 pages of newly declassified documents in Allied archives. From his own start as Marie Curie's lab assistant, Goldschmidt's career was closely intertwined with Frances complicated rise to membership in the nuclear club. As a refugee from the Nazis, he became part of the wartime nuclear energy project in Canada and found himself the only French scientist to work (although briefly) on the American atom bomb project.
Orbital excitation blockade and algorithmic cooling in quantum gases.
Bakr, Waseem S; Preiss, Philipp M; Tai, M Eric; Ma, Ruichao; Simon, Jonathan; Greiner, Markus
2011-12-21
Interaction blockade occurs when strong interactions in a confined, few-body system prevent a particle from occupying an otherwise accessible quantum state. Blockade phenomena reveal the underlying granular nature of quantum systems and allow for the detection and manipulation of the constituent particles, be they electrons, spins, atoms or photons. Applications include single-electron transistors based on electronic Coulomb blockade and quantum logic gates in Rydberg atoms. Here we report a form of interaction blockade that occurs when transferring ultracold atoms between orbitals in an optical lattice. We call this orbital excitation blockade (OEB). In this system, atoms at the same lattice site undergo coherent collisions described by a contact interaction whose strength depends strongly on the orbital wavefunctions of the atoms. We induce coherent orbital excitations by modulating the lattice depth, and observe staircase-like excitation behaviour as we cross the interaction-split resonances by tuning the modulation frequency. As an application of OEB, we demonstrate algorithmic cooling of quantum gases: a sequence of reversible OEB-based quantum operations isolates the entropy in one part of the system and then an irreversible step removes the entropy from the gas. This technique may make it possible to cool quantum gases to have the ultralow entropies required for quantum simulation of strongly correlated electron systems. In addition, the close analogy between OEB and dipole blockade in Rydberg atoms provides a plan for the implementation of two-quantum-bit gates in a quantum computing architecture with natural scalability.
Energy Technology Data Exchange (ETDEWEB)
Livingston, A.E.; Kukla, K.; Cheng, S. [Univ. of Toledo, OH (United States)] [and others
1995-08-01
In a collaboration with the Atomic Physics group at Argonne and the University of Toledo, the Atomic Physics group at the University of Notre Dame is measuring the fine structure transition energies in highly-charged lithium-like and helium-like ions using beam-foil spectroscopy. Precise measurements of 2s-2p transition energies in simple (few-electron) atomic systems provide stringent tests of several classes of current atomic- structure calculations. Analyses of measurements in helium-like Ar{sup 16+} have been completed, and the results submitted for publication. A current goal is to measure the 1s2s{sup 3}S{sub 1} - 1s2p{sup 3}P{sub 0} transition wavelength in helium-like Ni{sup 26+}. Measurements of the 1s2s{sup 2}S{sub 1/2} - 1s2p{sup 2}P{sub 1/2,3/2} transition wavelengths in lithium-like Kr{sup 33+} is planned. Wavelength and lifetime measurements in copper-like U{sup 63+} are also expected to be initiated. The group is also participating in measurements of forbidden transitions in helium-like ions. A measurement of the lifetime of the 1s2s{sup 3}S{sub 1} state in Kr{sup 34+} was published recently. In a collaboration including P. Mokler of GSI, Darmstadt, measurements have been made of the spectral distribution of the 2E1 decay continuum in helium-like Kr{sup 34+}. Initial results have been reported and further measurements are planned.
Surface-Induced Hybridization between Graphene and Titanium
Energy Technology Data Exchange (ETDEWEB)
Hsu, Allen L. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States).; Koch, Roland J. [Technische Universitat, Chemnitz (Germany); Ong, Mitchell T. [Stanford Univ., CA (United States); Fang, Wenjing [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Hofmann, Mario [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Kim, Ki Kang [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States).; Seyller, Thomas [Technische Universitat, Chemnitz (Germany); Dresselhaus, Mildred S. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Reed, Evan J. [Stanford Univ., CA (United States); Kong, Jing [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Palacios, Tomás [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States)
2014-08-26
Carbon-based materials such as graphene sheets and carbon nanotubes have inspired a broad range of applications ranging from high-speed flexible electronics all the way to ultrastrong membranes. However, many of these applications are limited by the complex interactions between carbon-based materials and metals. In this work, we experimentally investigate the structural interactions between graphene and transition metals such as palladium (Pd) and titanium (Ti), which have been confirmed by density functional simulations. We find that the adsorption of titanium on graphene is more energetically favorable than in the case of most metals, and density functional theory shows that a surface induced p-d hybridization occurs between atomic carbon and titanium orbitals. This strong affinity between the two materials results in a short-range ordered crystalline deposition on top of graphene as well as chemical modifications to graphene as seen by Raman and X-ray photoemission spectroscopy (XPS). This induced hybridization is interface-specific and has major consequences for contacting graphene nanoelectronic devices as well as applications toward metal-induced chemical functionalization of graphene.
Surface-induced hybridization between graphene and titanium.
Hsu, Allen L; Koch, Roland J; Ong, Mitchell T; Fang, Wenjing; Hofmann, Mario; Kim, Ki Kang; Seyller, Thomas; Dresselhaus, Mildred S; Reed, Evan J; Kong, Jing; Palacios, Tomás
2014-08-26
Carbon-based materials such as graphene sheets and carbon nanotubes have inspired a broad range of applications ranging from high-speed flexible electronics all the way to ultrastrong membranes. However, many of these applications are limited by the complex interactions between carbon-based materials and metals. In this work, we experimentally investigate the structural interactions between graphene and transition metals such as palladium (Pd) and titanium (Ti), which have been confirmed by density functional simulations. We find that the adsorption of titanium on graphene is more energetically favorable than in the case of most metals, and density functional theory shows that a surface induced p-d hybridization occurs between atomic carbon and titanium orbitals. This strong affinity between the two materials results in a short-range ordered crystalline deposition on top of graphene as well as chemical modifications to graphene as seen by Raman and X-ray photoemission spectroscopy (XPS). This induced hybridization is interface-specific and has major consequences for contacting graphene-nanoelectronic devices as well as applications toward metal-induced chemical functionalization of graphene.
Congenital orbital encephalocele, orbital dystopia, and exophthalmos.
Hwang, Kun; Kim, Han Joon
2012-07-01
We present here an exceedingly rare variant of a nonmidline basal encephalocele of the spheno-orbital type, and this was accompanied with orbital dystopia in a 56-year-old man. On examination, his left eye was located more inferolaterally than his right eye, and the patient said this had been this way since his birth. The protrusion of his left eye was aggravated when he is tired. His naked visual acuity was 0.7/0.3, and the ocular pressure was 14/12 mm Hg. The exophthalmometry was 10/14 to 16 mm. His eyeball motion was not restricted, yet diplopia was present in all directions. The distance from the midline to the medial canthus was 20/15 mm. The distance from the midline to the midpupillary line was 35/22 mm. The vertical dimension of the palpebral fissure was 12/9 mm. The height difference of the upper eyelid margin was 11 mm, and the height difference of the lower eyelid margin was 8 mm. Facial computed tomography and magnetic resonance imaging showed left sphenoid wing hypoplasia and herniation of the left anterior temporal pole and dura mater into the orbit, and this resulted into left exophthalmos and encephalomalacia in the left anterior temporal pole. To the best of our knowledge, our case is the second case of basal encephalocele and orbital dystopia.
2013-01-01
The main goal of this book is to provide a state of the art of hybrid metaheuristics. The book provides a complete background that enables readers to design and implement hybrid metaheuristics to solve complex optimization problems (continuous/discrete, mono-objective/multi-objective, optimization under uncertainty) in a diverse range of application domains. Readers learn to solve large scale problems quickly and efficiently combining metaheuristics with complementary metaheuristics, mathematical programming, constraint programming and machine learning. Numerous real-world examples of problems and solutions demonstrate how hybrid metaheuristics are applied in such fields as networks, logistics and transportation, bio-medical, engineering design, scheduling.
Directory of Open Access Journals (Sweden)
Balasubramanian Thiagarajan
2014-08-01
Full Text Available This article discusses various patterns of presentations of orbital lesions. Since this article has been authored by an otolaryngologist, the entire concept has been viewed from otolaryngologist's angle. With the advent of nasal endoscope trans nasal access to orbit is becoming the order of the day. Major advantage being that external skin incision is avoided.
LUNISOLAR INVARIANT RELATIVE ORBITS
Walid Ali Rahoma
2013-01-01
The present study deal with constructing an analytical model within Hamiltonian formulation to design invariant relative orbits due to the perturbation of J2 and the lunisolar attraction. To fade the secular drift separation over the time between two neighboring orbits, two second order conditions that guarantee that drift are derived and enforced to be equal.
Reticulohistiocytoma of the Orbit
Weissman, Heather M.; Hayek, Brent R.; Grossniklaus, Hans E.
2015-01-01
Reticulohistiocytoma is a rare, benign histiocytic proliferation of the skin or soft tissue. While ocular involvement has been documented in the past, there have been no previously reported cases of reticulohistiocytoma of the orbit. In this report, the authors describe a reticulohistiocytoma of the orbit in a middle-aged woman. PMID:24807799
Phipps, M J S; Fox, T; Tautermann, C S; Skylaris, C-K
2016-07-12
We report the development and implementation of an energy decomposition analysis (EDA) scheme in the ONETEP linear-scaling electronic structure package. Our approach is hybrid as it combines the localized molecular orbital EDA (Su, P.; Li, H. J. Chem. Phys., 2009, 131, 014102) and the absolutely localized molecular orbital EDA (Khaliullin, R. Z.; et al. J. Phys. Chem. A, 2007, 111, 8753-8765) to partition the intermolecular interaction energy into chemically distinct components (electrostatic, exchange, correlation, Pauli repulsion, polarization, and charge transfer). Limitations shared in EDA approaches such as the issue of basis set dependence in polarization and charge transfer are discussed, and a remedy to this problem is proposed that exploits the strictly localized property of the ONETEP orbitals. Our method is validated on a range of complexes with interactions relevant to drug design. We demonstrate the capabilities for large-scale calculations with our approach on complexes of thrombin with an inhibitor comprised of up to 4975 atoms. Given the capability of ONETEP for large-scale calculations, such as on entire proteins, we expect that our EDA scheme can be applied in a large range of biomolecular problems, especially in the context of drug design.
Quantum-Classical Connection for Hydrogen Atom-Like Systems
Syam, Debapriyo; Roy, Arup
2011-01-01
The Bohr-Sommerfeld quantum theory specifies the rules of quantization for circular and elliptical orbits for a one-electron hydrogen atom-like system. This article illustrates how a formula connecting the principal quantum number "n" and the length of the major axis of an elliptical orbit may be arrived at starting from the quantum…
Localization of molecular orbitals: from fragments to molecule.
Li, Zhendong; Li, Hongyang; Suo, Bingbing; Liu, Wenjian
2014-09-16
Conspectus Localized molecular orbitals (LMO) not only serve as an important bridge between chemical intuition and molecular wave functions but also can be employed to reduce the computational cost of many-body methods for electron correlation and excitation. Therefore, how to localize the usually completely delocalized canonical molecular orbitals (CMO) into confined physical spaces has long been an important topic: It has a long history but still remains active to date. While the known LMOs can be classified into (exact) orthonormal and nonorthogonal, as well as (approximate) absolutely localized MOs, the ways for achieving these can be classified into two categories, a posteriori top-down and a priori bottom-up, depending on whether they invoke the global CMOs (or equivalently the molecular density matrix). While the top-down approaches have to face heavy tasks of minimizing or maximizing a given localization functional typically of many adjacent local extrema, the bottom-up ones have to invoke some tedious procedures for first generating a local basis composed of well-defined occupied and unoccupied subsets and then maintaining or resuming the locality when solving the Hartree-Fock/Kohn-Sham (HF/KS) optimization condition. It is shown here that the good of these kinds of approaches can be combined together to form a very efficient hybrid approach that can generate the desired LMOs for any kind of gapped molecules. Specifically, a top-down localization functional, applied to individual small subsystems only, is minimized to generate an orthonormal local basis composed of functions centered on the preset chemical fragments. The familiar notion for atomic cores, lone pairs, and chemical bonds emerges here automatically. Such a local basis is then employed in the global HF/KS calculation, after which a least action is taken toward the final orthonormal localized molecular orbitals (LMO), both occupied and virtual. This last step is very cheap, implying that, after
Guo, Feng; Zhang, Na; Jin, Wei; Chang, Jun
2017-06-01
We theoretically study the dynamic time evolution following laser pulse pumping in an antiferromagnetic insulator Cr2O3. From the photoexcited high-spin quartet states to the long-lived low-spin doublet states, the ultrafast demagnetization processes are investigated by solving the dissipative Schrödinger equation. We find that the demagnetization times are of the order of hundreds of femtoseconds, in good agreement with recent experiments. The switching times could be strongly reduced by properly tuning the energy gaps between the multiplet energy levels of Cr3+. Furthermore, the relaxation times also depend on the hybridization of atomic orbitals in the first photoexcited state. Our results suggest that the selective manipulation of the electronic structure by engineering stress-strain or chemical substitution allows effective control of the magnetic state switching in photoexcited insulating transition-metal oxides.
Atomic Oxygen Cleaning of Unpainted Plaster Sculptures
Banks, Bruce A.; Miller, Sharon K.
2017-01-01
Atomic oxygen erosion of polymers has been found to be a threat to spacecraft in low Earth orbit. As a result ground facilities have been developed to identify coatings to protect polymers such as used for solar array blankets. As a result of extensive laboratory testing, it was discovered that soot and other organic contamination on paintings could be readily removed by atomic oxygen interactions with minimal damage to the artwork. No method, other than dusting, has been found to be effective in the cleaning of unpainted plaster sculptures This presentation discusses the atomic oxygen interaction processes and how effective they are for cleaning soot damaged unpainted plaster sculptures.
Quantum Simulations of Solvated Biomolecules Using Hybrid Methods
Hodak, Miroslav
2009-03-01
One of the most important challenges in quantum simulations on biomolecules is efficient and accurate inclusion of the solvent, because the solvent atoms usually outnumber those in the biomolecule of interest. We have developed a hybrid method that allows for explicit quantum-mechanical treatment of the solvent at low computational cost. In this method, Kohn-Sham (KS) density functional theory (DFT) is combined with an orbital-free (OF) DFT. Kohn-Sham (KS) DFT is used to describe the biomolecule and its first solvation shells, while the orbital-free (OF) DFT is employed for the rest of the solvent. The OF part is fully O(N) and capable of handling 10^5 solvent molecules on current parallel supercomputers, while taking only ˜ 10 % of the total time. The compatibility between the KS and OF DFT methods enables seamless integration between the two. In particular, the flow of solvent molecules across the KS/OF interface is allowed and the total energy is conserved. As the first large-scale applications, the hybrid method has been used to investigate the binding of copper ions to proteins involved in prion (PrP) and Parkinson's diseases. Our results for the PrP, which causes mad cow disease when misfolded, resolve a contradiction found in experiments, in which a stronger binding mode is replaced by a weaker one when concentration of copper ions is increased, and show how it can act as a copper buffer. Furthermore, incorporation of copper stabilizes the structure of the full-length PrP, suggesting its protective role in prion diseases. For alpha-synuclein, a Parkinson's disease (PD) protein, we show that Cu binding modifies the protein structurally, making it more susceptible to misfolding -- an initial step in the onset of PD. In collaboration with W. Lu, F. Rose and J. Bernholc.
Atomic Absorption Spectroscopy. The Present and the Future.
Slavin, Walter
1982-01-01
The status of current techniques and methods of atomic absorption (AA) spectroscopy (flame, hybrid, and furnace AA) is discussed, including limitations. Technological opportunities and how they may be used in AA are also discussed, focusing on automation, microprocessors, continuum AA, hybrid analyses, and others. (Author/JN)
Cetorelli, Nicola
2014-01-01
I introduce the concept of hybrid intermediaries: financial conglomerates that control a multiplicity of entity types active in the "assembly line" process of modern financial intermediation, a system that has become known as shadow banking. The complex bank holding companies of today are the best example of hybrid intermediaries, but I argue that financial firms from the "nonbank" space can just as easily evolve into conglomerates with similar organizational structure, thus acquiring the cap...
CSIR Research Space (South Africa)
Jacob John, Maya
2009-04-01
Full Text Available effect was observed for the elongation at break of the hybrid composites. The impact strength of the hybrid composites increased with the addition of glass fibres. The tensile and impact properties of thermoplastic natural rubber reinforced short... panels made from conventional structural materials. Figure 3 illustrates the performance of cellular biocomposite panels against conventional systems used for building and residential construction, namely a pre- cast pre-stressed hollow core concrete...
Stationary Light Pulses in Cold Atomic Media
Liao, Wen-Te; Peters, Thorsten; Chou, Hung-Chih; Wang, Jian-Siung; Kuan, Pei-Chen; Yu, Ite A
2008-01-01
Stationary light pulses (SLPs), i.e., light pulses without motion, are formed via the retrieval of stored probe pulses with two counter-propagating coupling fields. We show that there exist non-negligible hybrid Raman excitations in media of cold atoms that prohibit the SLP formation. We experimentally demonstrate a method to suppress these Raman excitations and realize SLPs in laser-cooled atoms. Our work opens the way to SLP studies in cold as well as in stationary atoms and provides a new avenue to low-light-level nonlinear optics.
Photoelectron spectroscopy of heavy atoms and molecules
Energy Technology Data Exchange (ETDEWEB)
White, M.G.
1979-07-01
The importance of relativistic interactions in the photoionization of heavy atoms and molecules has been investigated by the technique of photoelectron spectroscopy. In particular, experiments are reported which illustrate the effects of the spin-orbit interaction in the neutral ground state, final ionic states and continuum states of the photoionization target.
Atom Skimmers and Atom Lasers Utilizing Them
Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.
2005-01-01
Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.
Jovian Plasma Torus Interaction with Europa: 3D Hybrid Kinetic Simulation. First results
Lipatov, A. S.; Cooper, J. F.; Paterson, W. R.; Sittler, E. C.; Hartle, R. E.; Simpson, D. G.
2010-01-01
The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa-moon-magnetosphere system with respect to variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo orbiter mission, and for planning flyby and orbital measurements, (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy etal.,2007;Shematovichetal.,2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyro radius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream background ions).Non-thermal distributions of upstream plasma will be addressed in future work. Photoionization,electron-impact ionization, charge exchange and collisions between the ions and neutrals are also included in our model. We consider two models for background plasma:(a) with O(++) ions; (b) with O(++) and S(++) ions. The majority of O2 atmosphere is thermal with an extended cold population (Cassidyetal.,2007). A few first simulations already include an induced magnetic dipole; however, several important effects of induced magnetic fields arising from oceanic shell conductivity will be addressed in later work.
Observation of a Hybrid Spin Resonance
Bai, M.; Allgower, C.; Ahrens, L.; Alessi, J.; Brown, K.; Bunce, G.; Cameron, P.; Chu, C. M.; Courant, E. D.; Glenn, J. W.; Huang, H.; Jeon, D.; Kponou, A. E.; Krueger, K.; Luccio, A.; Makdisi, Y. I.; Lee, S. Y.; Ratner, L.; Reece, K.; Roser, T.; Spinka, H.; Syphers, M. J.; Tsoupas, N.; Underwood, D. G.; van Asselt, W.; Williams, N.; Yokosawa, A.
2000-02-01
A new type of spin depolarization resonance has been observed at the Brookhaven Alternating Gradient Synchrotron (AGS). This spin resonance is identified as a strong closed-orbit sideband around the dominant intrinsic spin resonance. The strength of the resonance was proportional to the 9th harmonic component of the horizontal closed orbit and proportional to the vertical betatron oscillation amplitude. This ``hybrid'' spin resonance cannot be overcome by the partial snake at the AGS, but it can be corrected by the harmonic orbit correctors.
Orbit Stabilization of Nanosat
Energy Technology Data Exchange (ETDEWEB)
JOHNSON,DAVID J.
1999-12-01
An algorithm is developed to control a pulsed {Delta}V thruster on a small satellite to allow it to fly in formation with a host satellite undergoing time dependent atmospheric drag deceleration. The algorithm uses four short thrusts per orbit to correct for differences in the average radii of the satellites due to differences in drag and one thrust to symmetrize the orbits. The radial difference between the orbits is the only input to the algorithm. The algorithm automatically stabilizes the orbits after ejection and includes provisions to allow azimuthal positional changes by modifying the drag compensation pulses. The algorithm gives radial and azimuthal deadbands of 50 cm and 3 m for a radial measurement accuracy of {+-} 5 cm and {+-} 60% period variation in the drag coefficient of the host. Approaches to further reduce the deadbands are described. The methodology of establishing a stable orbit after ejection is illustrated in an appendix. The results show the optimum ejection angle to minimize stabilization thrust is upward at 86{sup o} from the orbital velocity. At this angle the stabilization velocity that must be supplied by the thruster is half the ejection velocity. An ejection velocity of 0.02 m/sat 86{sup o} gives an azimuthal separation after ejection and orbit stabilization of 187 m. A description of liquid based gas thrusters suitable for the satellite control is included in an appendix.
Noël, Yves; De La Pierre, Marco; Zicovich-Wilson, Claudio M; Orlando, Roberto; Dovesi, Roberto
2014-07-14
The properties of the (n,n) icosahedral family of carbon fullerenes up to n = 10 (6000 atoms) have been investigated through ab initio quantum-mechanical simulation by using a Gaussian type basis set of double zeta quality with polarization functions (84,000 atomic orbitals for the largest case), the hybrid B3LYP functional and the CRYSTAL14 code featuring generalization of symmetry treatment. The geometry of giant fullerenes shows hybrid features, between a polyhedron and a sphere; as n increases, it approaches the former. Hexagon rings at face centres take a planar, graphene-like configuration; the 12 pentagon rings at vertices impose, however, a severe structural constraint to which hexagon rings at the edges must adapt smoothly, adopting a bent (rather than sharp) transversal profile and an inward longitudinal curvature. The HOMO and LUMO electronic levels, as well as the band gap, are well described using power laws. The gap is predicted to become zero for n ≥ 34 (69,360 atoms). The atomic excess energy with respect to the ideal graphene sheet goes to zero following the log(Nat)/Nat law, which is well described through the continuum elastic theory applied to graphene; the limits for the adopted model are briefly outlined. Compared to larger fullerenes of the series, C60 shows unique features with respect to all the considered properties; C240 presents minor structural and energetic peculiarities, too.
Quark Orbital Angular Momentum
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Burkardt Matthias
2015-01-01
Full Text Available Definitions of orbital angular momentum based on Wigner distributions are used as a framework to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. We find that the difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering.
Wijnands, Thijs; Srinivasan, B
2002-01-01
Orbit correction consists in adjusting the strengths of the corrector magnets to make the measured beam position match a predefined reference. In the LHC, this involves around 2000 sensors and more than 1000 actuators that are distributed along both rings. The orbit correction scheme should be able to compensate for very slow orbit drifts in the range of a 10-2 Hz but also for fast motions (vibrations) up to 1 Hz. In this paper we investigate correction schemes that could be used in either case. The choice of design formalisms is based on the experience we gained with the SPS and the LEP.
Teaching of Social and Philosophical Background to Atomic Theory.
Luhl, Jutta
1992-01-01
The history of atomic theory is outlined from earliest times up to the orbital model and describes a corresponding teaching method. The historical part of the paper emphasizes social and philosophical aspects in the development of atomic theory. The second part of the paper describes a method for teaching this material at the secondary level.…