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

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.