Title :

Perturbation Theory Treatment of Spin–Orbit Coupling, Part I: Double Perturbation Theory Based on a Single-Reference Initial Approximation

Author(s) :

Desmarais, Jacques [Auteur correspondant]
Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux [IPREM]
Dipartimento di Chimica [Torino]
Erba, Alessandro [Auteur]
Dipartimento di Chimica [Torino]
Flament, Jean-Pierre [Auteur]
Physico-Chimie Moléculaire Théorique [PCMT]
Kirtman, Bernard [Auteur correspondant]
Department of Chemistry and Biochemistry [Santa Barbara]

Journal title :

Journal of Chemical Theory and Computation

Pages :

4697-4711

Publisher :

American Chemical Society

Publication date :

2021-08-10

ISSN :

1549-9618

HAL domain(s) :

Chimie/Chimie théorique et/ou physique
Physique [physics]/Physique [physics]/Chimie-Physique [physics.chem-ph]

English abstract : [en]

We develop a perturbation theory for solving the many-body Dirac equation within a given relativistic effective-core potential approximation. Starting from a scalar-relativistic unrestricted Hartree–Fock (SR UHF) solution, ...
Show more >We develop a perturbation theory for solving the many-body Dirac equation within a given relativistic effective-core potential approximation. Starting from a scalar-relativistic unrestricted Hartree–Fock (SR UHF) solution, we carry out a double perturbation expansion in terms of spin–orbit coupling (SOC) and the electron fluctuation potential. Computationally convenient energy expressions are derived through fourth order in SOC, second order in the electron fluctuation potential, and a total of third order in the coupling between the two. Illustrative calculations on the halogen series of neutral and singly positive diatomic molecules show that the perturbation expansion is well-converged by taking into account only the leading (nonvanishing) term at each order of the electron fluctuation potential. Our perturbation theory approach provides a computationally attractive alternative to a two-component self-consistent field treatment of SOC. In addition, it includes coupling with the fluctuation potential through third order and can be extended (in principle) to multireference calculations, when necessary for both closed- and open-shell cases, using quasi-degenerate perturbation theory.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Internationale

Popular science :

Non

Collections :

• Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM) - UMR 8523

Source :

Harvested from HAL