Abstract: A many-body expansion interatomic potential obtained from bulk tin was used to predict the structures and energies of small and medium size tin clusters (Sn_2-Sn_(300)). The optimized results show that small tin clusters (Sn_2-Sn_(15)) prefer to take compact structures as their most stable configuration, all unrelated with the bulk lattice; while medium tin clusters, like, Sn_(47), Sn_(71), Sn_(87), and Sn_(147), are still kept in shell structures which are distortions of the microcrystalline fragments of solid tin, with all the shells compressed and some shells split. The energy per-atom of these clusters increases steadily with the increasing of the cluster size, approaching the cohesive energy of α-tin at about Sn_(740) (extrapolated), where the most stable structure should match the bulk lattice except for a few percents of surface atoms.

Key words: Tin clusters, Structures, Stabilities, Potential energy function