Melting and Equilibrium Shape of Icosahedral Gold Nanoparticles

We use molecular dynamics simulations to study the melting of gold icosahedral clusters of a few thousand atoms. We pay particular attention to the behavior of surface atoms, and to the equilibrium shape of the cluster. We find that although the surface of the cluster remains ordered up to the melting T_m, the increasing mobility of vertex and edge atoms significantly soften the surface structure, leading to inter- and intra-layer diffusion, and shrinking of the average facet size, so that the average shape of the cluster is nearly spherical at melting.