Relativistic extended coupled cluster method for magnetic hyperfine structure constant

TL;DR

This paper presents a relativistic extended coupled cluster method for accurately calculating magnetic hyperfine structure constants in atoms and molecules, demonstrating improved agreement with experimental data over previous methods.

Contribution

The paper introduces a 4-component spinor relativistic ECC method for open-shell systems, enhancing the accuracy of hyperfine structure constant calculations.

Findings

ECC results agree better with experimental values than RAS-CI.

The method successfully applied to alkali metals and alkaline earth ions.

Improved accuracy in hyperfine structure calculations.

Abstract

This article deals with the general implementation of 4-component spinor relativistic extended coupled cluster (ECC) method to calculate first order property of atoms and molecules in their open-shell ground state configuration. The implemented relativistic ECC is employed to calculate hyperfine structure (HFS) constant of alkali metals (Li, Na, K, Rb and Cs), singly charged alkaline earth metal atoms (Be+, Mg+, Ca+ and Sr+) and molecules (BeH, MgF and CaH). We have compared our ECC results with the calculations based on restricted active space configuration interaction (RAS-CI) method. Our results are in better agreement with the available experimental values than those of the RAS-CI values.