Molecular spinors from the quasi-relativistic pseudopotential approach

Hafner, P.; Schwarz, W. H. Eugen

doi:10.1016/0009-2614(79)80287-0

Cited by 95 publications

(48 citation statements)

References 20 publications

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“…In recent years several relativistic effective-potential formalisms [1][2][3][4][5] have been proposed and employed in electronic structure studies of molecules containing heavy elements. In most of these, relativistic contributions, except for spin-orbit, are introduced into the molecular calculations via the effective potentials, (EP).…”

Section: Introductionmentioning

confidence: 99%

Electronic structure for the ground state of TlH from relativistic multiconfiguration SCF calculations

Christiansen

Pitzer

1980

The Journal of Chemical Physics

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The dissociation curve for the ground state of TIH was computed using a relativistic w-w coupling formalism. The relativistic effects represented by the Dirac equation were introduced using effective potentials generated from atomic Dirac-Fock wavefunctions using a generalization of the improved effecti-..e potential formulation of Christiansen, Lee and Pitzer. The multi-configuration SCF treatment used is a generalization of the two-component molecular spinor formalism of Lee, Ermler and Pitzer. Using a five configuration wavefunction we were able to obtain approximately 85% of the experimental dissociation energy. Our computations indicate that the bond is principally sigma in form, despite the large spin-orbit splitting in atomic thallium.

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Section: Introductionmentioning

confidence: 99%

Electronic structure for the ground state of TlH from relativistic multiconfiguration SCF calculations

Christiansen

Pitzer

1980

The Journal of Chemical Physics

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“…(2), does not differ essentially from the nonrelativistic case, the SO contribution through the U SO term introduces nonzero spin off-diagonal matrix elements, inducing the effective one-electron wavefunctions to be composed by mixture of two functions corresponding to α and β spins (hence the name two-component). 21 Note that, in the onecomponent scalar relativistic scheme, the U AREP term is merely adopted in the Hamiltonian and as a result, the effective one-electron wavefunctions can be described by a set of the functions of a single spin, so-called spin orbitals.…”

Section: Theory and Implementationmentioning

confidence: 99%

“…The nonzero spin off-diagonal blocks of Fock matrix are due to direct results of the SO integrals and additional two-electron exchange integrals. 21 In the case of KRHF, time-reversal symmetry must be conserved during the diagonalization of Fock matrix and for this, we have implemented the diagonalization algorithms of Rösch 31 and Dongarra et al, 33 which are based on quaternion algebra. Moreover, Pulay's direct inversion in the iterative subspace (DIIS) procedure 34 has been modified for a two-component wavefunction and hired as an accelerator for SCF iteration.…”

Section: -28mentioning

confidence: 99%

KPACK: Relativistic Two-component Ab Initio Electronic Structure Program Package

Kim¹,

Lee²

2013

Bulletin of the Korean Chemical Society

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We describe newly developed software named KPACK for relativistic electronic structure computation of molecules containing heavy elements that enables the two-component ab initio calculations in Kramers restricted and unrestricted formalisms in the framework of the relativistic effective core potential (RECP). The spin-orbit coupling as relativistic effect enters into the calculation at the Hartree-Fock (HF) stage and hence, is treated in a variational manner to generate two-component molecular spinors as one-electron wavefunctions for use in the correlated methods. As correlated methods, KPACK currently provides the two-component second-order Møller-Plesset perturbation theory (MP2), configuration interaction (CI) and complete-activespace self-consistent field (CASSCF) methods. Test calculations were performed for the ground states of group-14 elements, for which the spin-orbit coupling greatly influences the determination of term symbols. A categorization of three procedures is suggested for the two-component methods on the basis of spin-orbit coupling manifested in the HF level.

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“…One can then construct double group symmetry functions where integrals over Hermitian operators become real quantities even when integrands and functions themselves are complex. 33 The two-component Kramer's restricted HF method ͑KRHF͒ that we use has also been derived by Hafner et al 34,35 Lee and Lee 36 have employed the method by utilizing the relativistic effective core potential ͑RECP͒ including the spin-orbit operator. Recently Mosyagin et al 37 applied generalized potentials ͑GRECP͒ to simulate the atomic core within a two-component j j coupled picture.…”

Section: Theorymentioning

confidence: 99%

Inclusion of mean-field spin–orbit effects based on all-electron two-component spinors: Pilot calculations on atomic and molecular properties

Iliaš

Kellö

Visscher

et al. 2001

The Journal of Chemical Physics

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An implementation of a two-component all-electron ( j j/ ) treatment of both scalar and spinorbit relativistic effects in the MOLFDIR program suite is presented. Relativity is accounted for by Douglas-Kroll transformed one-electron operators: scalar ͑spin-free͒ and so called mean-field spinorbit terms. The interelectronic interaction is represented by the nonrelativistic Coulomb operator. High-level correlated calculations of properties of several systems ͑FO, ClO, Cl, O 2 ϩ , O 2 Ϫ , Tl, and TlH͒ where spin-orbit effects play a dominant role are presented and compared with other data. Agreement with Dirac-Coulomb͑-Gaunt͒ reference values is in general very good.

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Molecular spinors from the quasi-relativistic pseudopotential approach

Cited by 95 publications

References 20 publications

Electronic structure for the ground state of TlH from relativistic multiconfiguration SCF calculations

Electronic structure for the ground state of TlH from relativistic multiconfiguration SCF calculations

KPACK: Relativistic Two-component Ab Initio Electronic Structure Program Package

Inclusion of mean-field spin–orbit effects based on all-electron two-component spinors: Pilot calculations on atomic and molecular properties

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