Cold collisions between alkali and alkaline-earth hetero nuclear atom-ion system Li + Ba$^+$

TL;DR

This paper theoretically investigates the quantum collision dynamics of the Li + Ba$^+$ atom-ion system, constructing potential energy surfaces and calculating scattering properties to understand elastic, spin-exchange, and diffusion processes.

Contribution

It provides the first detailed theoretical analysis of the Li-Ba$^+$ system's collisional behavior at quantum regimes, including potential energy surfaces and scattering cross sections.

Findings

Elastic, spin-exchange, and diffusion cross sections calculated.

Phase locking observed in spin-exchange collisions at low partial waves.

Semiclassical behavior analyzed at higher energies.

Abstract

In a recent experiment by Schaetz group \cite{weckesser2021}, the quantum $s$-wave regime has been attained for alkali and alkaline-earth atom-ion combination (Li-Ba$^+$). We investigate possible outcomes from interaction of this ion-atom pair at quantum regimes from a theoretical point of view. For this purpose, Born-Oppenheimer potential energy surfaces are constructed for the lowest three dissociation channels of (Ba-Li)$^+$ molecular system using a multireference configuration interaction (MRCI) electronic structure calculation. We present elastic, spin-exchange (SE), and diffusion cross sections at different energy regimes. The collisional properties of this system are calculated in terms of the scattering phase shifts and scattering cross sections, and the semiclassical behavior at a relatively large energy limit is also examined. For SE collisions, phase locking is obtained towards lower partial waves.