MOLECULAR-DYNAMICS EXAMINATION OF AN ANOMALOUS PHASE OF TEF6

At intermediate temperatures very large crystalline clusters of TeF6 exhibit a monoclinic phase that is unusual by several criteria, This phase is also generated in molecular dynamics computations designed to investigate phase transitions in clusters during cooling and heating cycles. The computer simulations place the problem into a coherent perspective by showing that the monoclinic phase is metastable, not thermodynamically stable, and is formed only by virtue of the kinetics of phase change. Results also clarify the relationship between the nonmetal and metal hexafluorides.