Crystallization and glass formation processes in liquid sodium: A molecular dynamics study

Abstract

Crystallization and glass formation processes are studied for the sodium system with 108 atoms by means of molecular dynamics simulation with constant volume. The equilibrium liquids, with four different initial conditions, are cooled with four different rates. The processes are analyzed by means of Voronoi polyhedra, diffusion coefficients, pair-distribution functions, and mean-square displacements. Embryo formation process, being accompanied by the abrupt slope increment of the displacement, appears with incubation period prior to nucleation and growth processes. The temperatures for the embryo formation and crystallization decrease with increasing cooling rate. The diffusion mechanism in supercooled liquid before the embryo formation is the same as that in equilibrium liquid. The critical cooling rate, which separates glass formation and crystallization processes, is greater than 8.00×1013 K s−1.