All-electron relativistic computations on the low-lying electronic states, bond length, and vibrational frequency of CeF diatomic molecule with spin-orbit coupling effects

Yusuke Kondo; Masato Kobayashi; Tomoko Akama; Takeshi Noro; Tetsuya Taketsugu

doi:10.1002/jcc.25171

All-electron relativistic computations on the low-lying electronic states, bond length, and vibrational frequency of CeF diatomic molecule with spin-orbit coupling effects

J Comput Chem. 2018 Jun 15;39(16):964-972. doi: 10.1002/jcc.25171. Epub 2018 Jan 30.

Authors

Yusuke Kondo¹, Masato Kobayashi², Tomoko Akama², Takeshi Noro², Tetsuya Taketsugu²

Affiliations

¹ Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-0810, Japan.
² Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan.

PMID: 29380861
DOI: 10.1002/jcc.25171

Abstract

Ab initio all-electron computations have been carried out for Ce⁺ and CeF, including the electron correlation, scalar relativistic, and spin-orbit coupling effects in a quantitative manner. First, the n-electron valence state second-order multireference perturbation theory (NEVPT2) and spin-orbit configuration interaction (SOCI) based on the state-averaged restricted active space multiconfigurational self-consistent field (SA-RASSCF) and state-averaged complete active space multiconfigurational self-consistent field (SA-CASSCF) wavefunctions have been applied to evaluations of the low-lying energy levels of Ce⁺ with [Xe]4f¹ 5d¹ 6s¹ and [Xe]4f¹ 5d² configurations, to test the accuracy of several all-electron relativistic basis sets. It is shown that the mixing of quartet and doublet states is essential to reproduce the excitation energies. Then, SA-RASSCF(CASSCF)/NEVPT2 + SOCI computations with the Sapporo(-DKH3)-2012-QZP basis set were carried out to determine the energy levels of the low-lying electronic states of CeF. The calculated excitation energies, bond length, and vibrational frequency are shown to be in good agreement with the available experimental data. © 2018 Wiley Periodicals, Inc.

Keywords: Lanthanide molecule; all-electron relativistic basis set; quasi-degeneracy of electronic states; spin-orbit coupling effect.