Melting behavior of nanometer sized gold isomers

In the present work, the melting behavior of nanometer sized gold isomers w as studied using a tight-binding potential with a second momentum approxima tion. The cases of cuboctahedra, icosahedra, Bagley decahedra, Marks decahe dra and star-like decahedra were considered. We calculated the temperature dependence of the total energy and volume during melting and the melting po int for different types and sizes of clusters. In addition, the structural evolutions of the nanosized clusters during the melting transition were mon itored and revealed. It is found that the melting process has three charact eristic time periods for the intermediate nanosized clusters. The whole pro cess includes surface disordering and reordering, followed by surface melti ng and a final rapid overall melting. This is a new observation, which it i s in contrast with previous reports where surface melting is the dominant s tep. (C) 2001 Elsevier Science B.V. All rights reserved.