PHASE-DIAGRAM OF ARGON CLUSTERS

Systems containing both argon cluster with number of atoms N = 100, 20 0, or 400 and argon vapor were studied with constant energy molecular dynamics simulations. The vapor pressure versus temperature phase diag ram including the melting temperatures was determined as a function of cluster particle number. The melting temperature of the cluster was d etermined with a new method based on the nearest-neighbor exchange of atoms, and it was found to approach the bulk melting temperature linea rly as a function of N-1/3. The vapor pressure versus temperature curv e approached the corresponding bulk curve as the particle number of th e cluster increased. At temperatures lower than the melting temperatur es the clusters were found to contain an icosahedral core. (C) 1998 Am erican Institute of Physics.