Coexistence in small inert gas clusters

Abstract

The coexistence of solid-like and liquid-like forms of a finite atomic cluster is examined analytically and numerically using model densities of states and partition functions. Within the harmonic normal mode approximation we can calculate the caloric curve, heat capacity and total energy probability distribution of a finite atomic cluster from a single molecular dynamics trajectory. The method requires data from a high energy simulation in the microcanonical ensemble, along with systematic quenching, to provide statistics about local minima. The results provide new insight into the coexistence of solid-like and liquid-like forms of such clusters, with a clear S-bend in the microcanonical caloric curve and a bimodal distribution of the total energy around the transition temperature for a 55 atom system.