Microsolvation of cationic dimers in $^4$He droplets: geometries of A$_2^+$(He)$_N$ (A=Li,Na,K) from optimized energies

TL;DR

This study uses ab initio calculations and genetic algorithms to explore how small helium droplets microsolvate cationic dimers (Li, Na, K), revealing common patterns in cluster growth and structure.

Contribution

It introduces a combined ab initio and genetic algorithm approach to determine the geometries of A$_2^+$(He)$_N$ clusters, highlighting the symmetry and growth features of solvation.

Findings

Small clusters grow symmetrically around the cationic dimers.

The solvation process shows a common pattern across Li, Na, and K.

Optimized geometries reveal specific symmetry features of the clusters.

Abstract

Ab initio computed interaction forces are employed in order to describe the microsolvation of the A$_2^+(^2\Sigma)$ (A=Li,Na,K) molecular ion in $^4$He clusters of small variable size. The minimum energy structures are obtained by performing energy minimization based on a genetic algorithm approach. The symmetry features of the collocation of solvent adatoms around the dimeric cation are analyzed in detail, showing that the selective growth of small clusters around the two sides of the ion during the solvation process is a feature common to all three dopants.