Phase transitions in molecular clusters

Using classical Monte Carlo techniques, anomalies in the constant volume heat capacity as a function of temperature are observed for (CO)(5) and (N-2)(5). These anomalies have been related to cluster phase transitions. The usual solid-liquid coexistence region is observed for both systems. However, for (CO)(5) a low-temperature phase transition is observed that is associated with an orientational change in the molecular components of the system. Root-mean-square bond fluctuations and distribution of potential energies are used to characterize the various phase transitions. (C) 1997 American Institute of Physics.