LAUSR

Abstract Recent mass spectrometry measurements carried out for the coronene (C 24 H 12 ) cation coated with helium atoms have revealed special stabilities associated with ’magic numbers’ at sizes 38, 41, and 44, the latter being interpreted as the signature of a complete first solvation shell. In the present contribution we examine by means of path-integral molecular dynamics simulations employing a polarizable potential the equilibrium structures of such clusters and how they differ from the classical global minima. Our results confirm the special energetic stability of the suggested sizes and the highly symmetric geometric arrangement of the helium atoms around the aromatic cation. However, they also indicate that the helium atoms in the vicinity of the aromatic plane are highly fluxional and not associated with a unique local minimum in the energy landscape. Above the size of 44, the shell expands but remains stable with no immediate evidence for a second shell.