MOLECULAR-DYNAMICS STUDY OF THE CRYSTALLIZATION OF METASTABLE FLUIDS

Using the molecular dynamics technique we have investigated the mechan isms by which a metastable Lennard-Jones fluid transforms into a cryst al and the morphology of the final state produced. The metastable stat es were created by equilibrating the fluid state at a temperature abov e the critical temperature then rapidly quenching to a temperature bel ow the triple-point temperature. The starting densities were chosen so that the system was in the metastable two-phase region of the phase d iagram after the quench. Three quite distinct starting densities were used corresponding to a low-density gas, a critical-density gas and a gas at a density of a typical liquid. For each of these starting condi tions, the final state observed consists of crystalline and gaseous re gions. However, the mechanism by which these states were reached and t he morphology of the final state was quite distinct in the three cases studied.