Optimal covering of C60 fullerene by rare gases

Putative global energy minima of clusters formed by the adsorption of rare gases on a C-60 fullerene molecule, C60XN (X=Ne, Ar, Kr, Xe; N <= 70), are found using basin-hopping global optimization in an empirical potential energy surface. The association energies per rare gas atom as a function of N present two noticeable minima for Ne and Ar and just one for Kr and Xe. The minimum with the smallest N is the deepest one and corresponds to an optimal packing monolayer structure; the other one gives a monolayer with maximum packing. For Kr and Xe, optimal and maximum packing structures coincide. By using an isotropic average form of the X-C-60 interaction, we have established the relevance of the C-60 surface corrugation on the cluster structures. Quantum effects are relevant for Ne clusters. The adsorption of these rare gases on C-60 follows patterns that differ significantly from the ones found recently for He by means of experimental and theoretical methods. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4742820]