Potential energy surfaces of the low-lying electronic states of the Li + LiCs system

TL;DR

This study uses ab initio quantum chemistry to map potential energy surfaces of low-lying electronic states in the Li + LiCs system, revealing attractive interactions relevant for cold molecule experiments.

Contribution

It provides detailed potential energy surfaces and analyzes three-body forces for the Li + LiCs system, a novel contribution to understanding alkali triatomic interactions.

Findings

Global minima identified for ground and excited states.

Strongly attractive dimer-atom interactions observed.

Potential relevance for cold alkali polar dimer experiments.

Abstract

Ab initio quantum chemistry calculations are performed for the mixed alkali triatomic system. Global minima of the ground and first excited doublet states of the trimer are found and Born-Oppenheimer potential energy surfaces of the Li atom interacting with the LiCs molecule were calculated for these states. The lithium atom is placed at various distances and bond angles from the lithium-caesium dimer. Three-body nonadditive forces of the Li$_2$Cs molecule in the global minimum are investigated. Dimer-atom interactions are found to be strongly attractive and may be important in the experiments, particularly involving cold alkali polar dimers.