Molecular Dynamics Studies of the Kinetics of Phase Changes in Clusters: Crystal Nucleation of (RbCl)108 Clusters at 600, 550, and 500 K

Abstract

Molecular dynamics computer simulations based on the Born–Mayer–Huggins potential function have been employed to study the crystal nucleation of (RbCl)108 clusters. When a completely melted (RbCl)108 cluster was cooled down at a cooling rate of 2.5×1011 K/s, nucleation and crystal growth into the NaCl-type structure crystal was observed at the temperature ∼600 K. When a melted (RbCl)108 cluster was quenched from 900 K to a bath with a temperature from 600 to 500 K and kept in the bath for a time period up to ∼720 ps, both nucleation and crystal growth into the NaCl-type crystals were observed. Nucleation rates of crystallization at 600, 550, and 500 K are estimated and the interfacial free energy of the liquid–solid boundary was derived from the nucleation rates using the classical nucleation theory. The diffuse interface thickness was also estimated. The possibility of the transition from NaCl-type to CsCl-type structure under high Laplace pressure is discussed.