Lithium ions solvated in helium

TL;DR

This study combines experimental and theoretical approaches to investigate lithium ions solvated by helium atoms, revealing specific stable cluster sizes and demonstrating agreement between classical and quantum computational methods.

Contribution

It provides new insights into the solvation structures of Li$^+$ in helium and compares classical and quantum methods for modeling these clusters.

Findings

Enhanced abundances at specific cluster sizes (n=2, 6, 8, 14)

Classical methods qualitatively agree with quantum approaches on energies and structures

Identification of particularly stable structures at n=4, 6, and 8

Abstract

We report on a combined experimental and theoretical study of Li$^+$ ions solvated by up to 50 He atoms. The experiments show clear enhanced abundances associated with He$_n$Li$^+$ clusters where $n=2$, 6, 8, and 14. We find that classical methods, e.g.\ Basin-Hopping (BH), give results that qualitatively agree with quantum mechanical methods such as path integral Monte Carlo, diffusion Monte Carlo and quantum free energy, regarding both energies and the solvation structures that are formed. The theory identifies particularly stable structures for $n=4$, 6 and 8 which line up with some of the most abundant features in the experiments.