Melting and equilibrium shape of icosahedral gold nanoparticles

Abstract 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 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. Key words: Clusters, gold nanocrystals, molecular dynamics PACS: 05.45.-a, 79.60.-I Gold particles consisting of tens to thousands of atoms have unique optical and mechanical properties and hold great promise as building blocks for nanobioelectronic devices [1,2], catalysts While bulk gold has an fcc crystal structure, the competition between bulk and surface energies in nanometer sized gold crystallites can result in several different competing structure