Analytic gradients for relativistic exact-two-component equation-of-motion coupled-cluster singles and doubles method

Chaoqun Zhang; Xuechen Zheng; Junzi Liu; Ayush Asthana; Lan Cheng

doi:10.1063/5.0175041

Analytic gradients for relativistic exact-two-component equation-of-motion coupled-cluster singles and doubles method

J Chem Phys. 2023 Dec 28;159(24):244113. doi: 10.1063/5.0175041.

Authors

Chaoqun Zhang¹, Xuechen Zheng¹, Junzi Liu¹, Ayush Asthana¹, Lan Cheng¹

Affiliation

¹ Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.

PMID: 38153147
DOI: 10.1063/5.0175041

Abstract

A first implementation of analytic gradients for spinor-based relativistic equation-of-motion coupled-cluster singles and doubles method using an exact two-component Hamiltonian augmented with atomic mean-field spin-orbit integrals is reported. To demonstrate its applicability, we present calculations of equilibrium structures and harmonic vibrational frequencies for the electronic ground and excited states of the radium mono-amide molecule (RaNH2) and the radium mono-methoxide molecule (RaOCH3). Spin-orbit coupling is shown to quench Jahn-Teller effects in the first excited state of RaOCH3, resulting in a C3v equilibrium structure. The calculations also show that the radium atoms in these molecules serve as efficient optical cycling centers.