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 the surface of the cluster does not pre-melt, but rather remains ordered up to the melting T-m. However, the increasing mobility of vertex and edge atoms significantly softens 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. (C) 2004 Elsevier B.V. All rights reserved.