Ab initio properties of Li-Group-II molecules for ultracold matter studies

TL;DR

This study uses advanced quantum chemistry methods to analyze the electronic properties of Li-alkaline-earth molecules, revealing irregularities in dissociation energies and dipole moments, aiding their potential use in quantum simulations.

Contribution

First comprehensive ab initio analysis of Li-Group-II molecules' electronic properties for ultracold matter applications.

Findings

Irregular dissociation energy and bond length trends with increasing reduced mass.

Dipole moments vary significantly, smallest in heaviest molecules, larger in lighter ones.

Results support further exploration of these molecules in optical trapping and quantum simulation.

Abstract

We perform a systematic investigation of the electronic properties of the $^2\Sigma^+$ ground state of Li-alkaline-earth dimers. These molecules are proposed as possible candidates for quantum simulation of lattice-spin models. We apply powerful quantum chemistry coupled-cluster methods with large basis sets to calculate potential energies, permanent dipole moment, and electron density distributions for LiBe, LiMg, LiCa, LiSr, and LiYb. Our results reveal a surprising irregularity in the dissociation energy and bond length with an increase in the reduced mass of the molecule. At the same time the permanent dipole moment at the equilibrium separation has the smallest value between 0.01 a.u. and 0.1 a.u. for the heaviest (LiSr and LiYb) molecules and increases to 1.4 a.u. for the lightest (LiBe), where 1 a.u. is one atomic unit of dipole moment. We consider our study of the $^2\Sigma^+$ molecules a first step towards a comprehensive analysis of their interactions in an optical trap.