Melting of clusters with pair interaction of atoms

Analysis of the melting of clusters with pair interaction of atoms by methods of molecular dynamics has revealed special features of the melting process which are useful for the understanding of the microscopic nature of phase transitions in condensed systems. One of these features is the coexistence of solid and liquid phases in a cluster in some temperature range the width of which is inversely proportional to the number of atoms participating in the transition. The melting process is governed by collective motion of cluster atoms, and a potential barrier separates the solid and liquid phases. The physical picture of the melting process has been obtained from computer modeling of clusters. The results demonstrate that the liquid state of clusters with filled shells can be regarded as the lowest excited state with a large statistical weight, and that simple cluster models in which atoms not participating in the transitions are assumed to stay fixed in their lattice sites can describe the melting process only qualitatively.