Simulating ionic microsolvation: protonated argon clusters

The elementary dynamical steps which occur during the solvation of an initially 'naked' proton are examined in the case of argon used as a 'solvent'. The process is studied by employing ab initio molecular dynamics which describes the ionic interactions as fully many-body interactions within a density-functional approach that includes gradient corrections. The most stable configurations of the small clusters are obtained using both geometry optimization and simulated temperature annealing procedures, and the competition between the H+ and its nearest Ar neighbour as possible nucleation sites is analysed and discussed. The present results confirm that (ArH)(+) is the dominant ionic moiety within the inner solvation shells of protonated small clusters.