Stability of Phase Coexistence in Atomic Clusters

Microcanonical critical droplet theory and molecular dynamics simulations are used to examine static coexistence between solid and liquid phases in nanoscale lead clusters. It is shown that the theory predicts the existence of a metastable coexisting state above a critical cluster radius $R_1$, with this state becoming stable for clusters of radius $R > R_2$. Molecular dynamics simulations of lead clusters confirm the existence of stable coexisting states in 1427-atom and 2057-atom clusters but find no stable coexisting state in a 931-atom cluster.