Spin-orbit effects on structures of closed-shell polyatomic molecules containing heavy atoms calculated by two-component Hartree-Fock method

Abstract Focusing on relative stabilities of electronic states with different spin multiplicities of polyatomic molecules, a simplified unrestricted Hartree-Fock (SUHF) procedure is described. Using different orbitals for different spins (DODS), electron correlation effects of both closed-shell and open-shell systems are expected to be taken into account in the simplest way. While working within a symmetrically orthogonalized (Löwdin) basis we make use of the NDDO approximation (neglect of diatomic differential overlap) concerning the evaluation of electron repulsion and nuclear attraction integrals. Originally, a locally orthogonalized all-electron atomic orbital set of Slater type is considered. The approximation method is completely non-empirical. Rotational invariance is fully retained.

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Kramers' restricted hartree?fock method for polyatomic molecules usingab initio relativistic effective core potentials with spin?orbit operators

Journal of Computational Chemistry ◽

10.1002/jcc.540130509 ◽

1992 ◽

Vol 13 (5) ◽

pp. 595-601 ◽

Cited By ~ 37

Author(s):

Sang Yeon Lee ◽

Yoon Sup Lee

Keyword(s):

Polyatomic Molecules ◽

Spin Orbit ◽

Hartree Fock ◽

Effective Core Potentials

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Spin-orbit coupling from a two-component self-consistent approach. I. Generalized Hartree-Fock theory

The Journal of Chemical Physics ◽

10.1063/1.5114901 ◽

2019 ◽

Vol 151 (7) ◽

pp. 074107

Author(s):

Jacques K. Desmarais ◽

Jean-Pierre Flament ◽

Alessandro Erba

Keyword(s):

Orbit Coupling ◽

Spin Orbit Coupling ◽

Spin Orbit ◽

Hartree Fock ◽

Two Component ◽

Self Consistent ◽

Consistent Approach

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Single Atom Image Contrast in Fixed Beam Dark Field Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100051840 ◽

1974 ◽

Vol 32 ◽

pp. 366-367

Author(s):

Wah Chi

Keyword(s):

Scattering Amplitude ◽

Present Report ◽

Dark Field ◽

Image Contrast ◽

Single Atom ◽

Optical Theorem ◽

Hartree Fock ◽

Heavy Atoms ◽

Beam Stop ◽

Fixed Beam

Resolution and contrast are the important factors to determine the feasibility of imaging single heavy atoms on a thin substrate in an electron microscope. The present report compares the atom image characteristics in different modes of fixed beam dark field microscopy including the ideal beam stop (IBS), a wire beam stop (WBS), tilted illumination (Tl) and a displaced aperture (DA). Image contrast between one Hg and a column of linearly aligned carbon atoms (representing the substrate), are also discussed. The assumptions in the present calculations are perfectly coherent illumination, atom object is represented by spherically symmetric potential derived from Relativistic Hartree Fock Slater wave functions, phase grating approximation is used to evaluate the complex scattering amplitude, inelastic scattering is ignored, phase distortion is solely due to defocus and spherical abberation, and total elastic scattering cross section is evaluated by the Optical Theorem. The atom image intensities are presented in a Z-modulation display, and the details of calculation are described elsewhere.

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Polaronic and Bipolaronic Enhancement of Second Hyperpolarizabilities in Dithienyl Polyenes from Ab Initio Quantum Methods

MRS Proceedings ◽

10.1557/proc-597-319 ◽

1999 ◽

Vol 597 ◽

Author(s):

Steven Trohalaki ◽

Robert J. Zellmer ◽

Ruth Pachter

Keyword(s):

Ab Initio ◽

Density Functional ◽

Valence Bond ◽

Closed Shell ◽

Functional Theory ◽

Molecular Conformations ◽

Hartree Fock ◽

Molecular Charge ◽

Field Methodology ◽

Moller Plesset

AbstractSpangler and He [1,2] have shown that dithienyl polyenes form extremely stable bipolaronic dications when oxidatively doped in solution. Previous theoretical studies applied empirical methods to predict bipolaronic enhancement of hyperpolarizabilities for simple polyenes [3,4]. Here, we employ density functional theory to optimize the gas-phase molecular conformations of neutral, cationic, and dicationic forms of a series of dithienyl polyenes, where the number of ethene units, N, is varied from 1–5. Ab initio Hartree-Fock, generalized valence bond, configuration interaction, and Møller-Plesset calculations demonstrate that the dications are farily well described with a closed shell and therefore have little biradicaloid character. Second hyperpolarizabilities, γ, are subsequently calculated using ab initio Hartree-Fock theory and a finite field methodology. As expected, γ increases with the number of ethene units for a given molecular charge. The cations also show the largest increase in γ with N. For a given value of N, the cations display the largest γ values. However, if we treat the dication as a triplet, which might be present in solution, then it displays the largest γ.

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