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Title: Two-component multi-configurational second-order perturbation theory with Kramers restricted complete active space self-consistent field reference function and spin-orbit relativistic effective core potential

Abstract

We report the formulation and implementation of KRCASPT2, a two-component multi-configurational second-order perturbation theory based on Kramers restricted complete active space self-consistent field (KRCASSCF) reference function, in the framework of the spin-orbit relativistic effective core potential. The zeroth-order Hamiltonian is defined as the sum of nondiagonal one-electron operators with generalized two-component Fock matrix elements as scalar factors. The Kramers symmetry within the zeroth-order Hamiltonian is maintained via the use of a state-averaged density, allowing a consistent treatment of degenerate states. The explicit expressions are derived for the matrix elements of the zeroth-order Hamiltonian as well as for the perturbation vector. The use of a fully variational reference function and nondiagonal operators in relativistic multi-configurational perturbation theory is reported for the first time. A series of initial calculations are performed on the ionization potential and excitation energies of the atoms of the 6p-block; the results display a significant improvement over those from KRCASSCF, showing a closer agreement with experimental results. Accurate atomic properties of the superheavy elements of the 7p-block are also presented, and the electronic structures of the low-lying excited states are compared with those of their lighter homologues.

Authors:
Publication Date:
OSTI Identifier:
22310724
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 141; Journal Issue: 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ELECTRONIC STRUCTURE; ELECTRONS; EXCITATION; EXCITED STATES; HAMILTONIANS; MATRIX ELEMENTS; PERTURBATION THEORY; SELF-CONSISTENT FIELD; SPIN; TRANSACTINIDE ELEMENTS

Citation Formats

Kim, Inkoo, and Lee, Yoon Sup, E-mail: yslee@kaist.edu. Two-component multi-configurational second-order perturbation theory with Kramers restricted complete active space self-consistent field reference function and spin-orbit relativistic effective core potential. United States: N. p., 2014. Web. doi:10.1063/1.4898153.
Kim, Inkoo, & Lee, Yoon Sup, E-mail: yslee@kaist.edu. Two-component multi-configurational second-order perturbation theory with Kramers restricted complete active space self-consistent field reference function and spin-orbit relativistic effective core potential. United States. https://doi.org/10.1063/1.4898153
Kim, Inkoo, and Lee, Yoon Sup, E-mail: yslee@kaist.edu. 2014. "Two-component multi-configurational second-order perturbation theory with Kramers restricted complete active space self-consistent field reference function and spin-orbit relativistic effective core potential". United States. https://doi.org/10.1063/1.4898153.
@article{osti_22310724,
title = {Two-component multi-configurational second-order perturbation theory with Kramers restricted complete active space self-consistent field reference function and spin-orbit relativistic effective core potential},
author = {Kim, Inkoo and Lee, Yoon Sup, E-mail: yslee@kaist.edu},
abstractNote = {We report the formulation and implementation of KRCASPT2, a two-component multi-configurational second-order perturbation theory based on Kramers restricted complete active space self-consistent field (KRCASSCF) reference function, in the framework of the spin-orbit relativistic effective core potential. The zeroth-order Hamiltonian is defined as the sum of nondiagonal one-electron operators with generalized two-component Fock matrix elements as scalar factors. The Kramers symmetry within the zeroth-order Hamiltonian is maintained via the use of a state-averaged density, allowing a consistent treatment of degenerate states. The explicit expressions are derived for the matrix elements of the zeroth-order Hamiltonian as well as for the perturbation vector. The use of a fully variational reference function and nondiagonal operators in relativistic multi-configurational perturbation theory is reported for the first time. A series of initial calculations are performed on the ionization potential and excitation energies of the atoms of the 6p-block; the results display a significant improvement over those from KRCASSCF, showing a closer agreement with experimental results. Accurate atomic properties of the superheavy elements of the 7p-block are also presented, and the electronic structures of the low-lying excited states are compared with those of their lighter homologues.},
doi = {10.1063/1.4898153},
url = {https://www.osti.gov/biblio/22310724}, journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 16,
volume = 141,
place = {United States},
year = {Tue Oct 28 00:00:00 EDT 2014},
month = {Tue Oct 28 00:00:00 EDT 2014}
}