Melting Behavior of (AgI)_n Clusters by Molecular Dynamics Simulation

Lowest energy structures of (AgI)n (n=3-15) clusters were investigated by using a genetic algorithm based on empirical potential. The melting behavior of these clusters was studied by means of a microcanonical molecular dynamics simulation. Stable structures of (AgI)n clusters are mainly cages composed of four- and six-membered rings. For most (AgI)n clusters molecular dynamics simulation shows that the fluctuation of atomic distances and kinetic energies increases with increasing temperature and the structures gradually melt within a larger temperature range. The (AgI)6 cluster has high symmetry and it melts in a narrow temperature range. For the (AgI)5 cluster the most stable cage structure may transform into a ring structure of higher energy before melting which results in negative heat capacity.