Electric Dipole Moments and Static Dipole Polarizabilities of Alkali--Alkaline-Earth Molecules: Non-relativistic versus relativistic coupled-cluster theory analyses

TL;DR

This study compares non-relativistic and relativistic coupled-cluster calculations of electric dipole moments and polarizabilities in alkali-alkaline-earth molecules, providing insights into electron correlation, relativistic effects, and empirical estimation methods.

Contribution

It offers a comprehensive analysis of relativistic and non-relativistic effects on dipole properties of alkali-alkaline-earth molecules using coupled-cluster methods, including empirical relations for property estimation.

Findings

Relativistic effects significantly influence dipole moments and polarizabilities.

Empirical relations can estimate polarizabilities based on atomic properties.

Uncertainties are quantified through various computational parameters.

Abstract

We analyze the electric dipole moments (PDMs) and static electric dipole polarizabilities of the alkali--alkaline-earth (Alk-AlkE) dimers by employing finite-field coupled-cluster methods, both in the frameworks of non-relativistic and four-component spinfree relativistic theory. In order to carry out comparative analyses rigorously, we consider those Alk-AlkE molecules made out of the lightest to the medium-heavy constituent atoms (Alk: Li to Rb and AlkE: Be through Sr). We present behaviour of electron correlation effects as well as relativistic effects with the size of the molecules. Uncertainties to the above quantities of the investigated Alk-AlkE molecules are inferred by analyzing our results from different form of Hamiltonian, basis set, and perturbative parameter in a few representative molecules. We have also provided empirical relations by connecting average polarizabilities of the Alk-AlkE molecules with their PDMs, and atomic numbers and polarizabilities of the corresponding Alk and AlKE atoms, which can be used to roughly estimate the average polarizabilities of other heavier Alk-AlkE molecules. We finally give our recommended results, and compare them with the literature values.