Molecular Dynamics Simulation of the Melting Behaviours of 12-, 13-, 14-Atom Icosahedral Platinum Clusters

Using molecular dynamics simulation technique, we have studied the melting behaviours of free, icosahedral PtN clusters in the size range of N=12-14. Voter and Chen version of an embedded-atom model, derived by fitting to experimental data of both diatomic molecule and bulk platinum simultaneously, has been employed in the study. We present an atom-resolved analysis method that includes physical quantities such as the root-mean-square bond-length fluctuation and coordination number for individual atoms as functions of temperature. The results show that while 13-atom icosahedron and 12-atom cluster with a vacancy on the icosahedral surface exhibit one-stage melting, 14-atom cluster with an adatom on the icosahedral surface undergoes two-stage melting, as the temperature increases.