Relativistic equation-of-motion coupled-cluster method for the electron attachment problem

TL;DR

This paper develops and applies a relativistic equation-of-motion coupled-cluster method for electron attachment, accurately calculating ionization potentials and electron affinities of alkali metals and related molecules, including spin-orbit effects.

Contribution

It introduces a relativistic EA-EOMCC method at the single and double excitation level and demonstrates its accuracy for atomic and molecular systems with spin-orbit considerations.

Findings

Results agree with NIST data within 1%

Both four-component and two-component calculations are effective

Spin-orbit effects are significant in atomic systems

Abstract

The article considers the successful implementation of relativistic equation-of-motion coupled cluster method for the electron attachment problem (EA-EOMCC) at the level of single- and double- excitation approximation. The implemented relativistic EA-EOMCC method is employed to calculate ionization potential values of alkali metal atoms (Li, Na, K, Rb, Cs, Fr) and the vertical electron affinity values of LiX (X = H, F, Cl, Br), NaY (Y = H, F, Cl) starting from their closed-shell configuration. Both four-component and exact two-component calculations are done for all the opted systems. Further, we have shown the effect of spin-orbit interaction considering the atomic systems. The results of our atomic calculations are compared with the values from the NIST database and the results are found to be very accurate (< 1 %).