DOI: 10.1063/5.0175041 ISSN: 0021-9606

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
  • Physical and Theoretical Chemistry
  • General Physics and Astronomy

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.

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