Relativistic double-ionization equation-of-motion coupled-cluster method: Application to low-lying doubly ionized states

Himadri Pathak; Sudip Sasmal; Kaushik Talukdar; Malaya K Nayak; Nayana Vaval; Sourav Pal

doi:10.1063/1.5140988

Relativistic double-ionization equation-of-motion coupled-cluster method: Application to low-lying doubly ionized states

J Chem Phys. 2020 Mar 14;152(10):104302. doi: 10.1063/1.5140988.

Authors

Himadri Pathak¹, Sudip Sasmal¹, Kaushik Talukdar², Malaya K Nayak³, Nayana Vaval¹, Sourav Pal²

Affiliations

¹ Electronic Structure Theory Group, Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.
² Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
³ Theoretical Chemistry Section, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.

PMID: 32171231
DOI: 10.1063/1.5140988

Abstract

This article deals with the extension of the relativistic double-ionization equation-of-motion coupled-cluster (DI-EOMCC) method [H. Pathak et al. Phys. Rev. A 90, 010501(R) (2014)] for the molecular systems. The Dirac-Coulomb Hamiltonian with four-component spinors is considered to take care of the relativistic effects. The implemented method is employed to compute a few low-lying doubly ionized states of noble gas atoms (Ar, Kr, Xe, and Rn) and Cl₂, Br₂, HBr, and HI. Additionally, we presented results with two intermediate schemes in the four-component relativistic DI-EOMCC framework to understand the role of electron correlation. The computed double ionization spectra for the atomic systems are compared with the values from the non-relativistic DI-EOMCC method with spin-orbit coupling [Z. Wang et al. J. Chem. Phys. 142, 144109 (2015)] and the values from the National Institute of Science and Technology (NIST) database. Our atomic results are found to be in good agreement with the NIST values. Furthermore, the obtained results for the molecular systems agree well with the available experimental values.