FREEZING, MELTING, NONWETTING, AND COEXISTENCE IN (KCL)32

Binary clusters, notably salt clusters with their combination of attractive and repulsive long-range forces, exhibit structural and dynamical behavior different from that of homogeneous clusters. The melting and freezing, nonwetting, and the complexity of the potential surface of (KCl)32 are used to make the comparison. A new method to estimate the density of configurational states is described and applied to the evaluation of thermodynamic properties of (KCl)32. In particular, with this new method we compute for several temperatures the fraction or probability, P(phi,beta), of clusters vibrating around a configuration with minimum energy phi. The behavior of P(phi,beta) with temperature T is indicative of a coexistence of solidlike and liquidlike forms of (KCl)32 for a range of temperatures. The input data required by this new method can be obtained from constant temperature molecular dynamics simulations.