Molecular dynamics simulation of homogeneous nucleation in a superheated Lennard-Jones crystal

摘要

We present the results of a molecular dynamics study of homogeneous nucleation of liquid drops in a superheated Lennard-Jones (LJ) crystal at positive and negative pressures. The mean lifetime method has been used to determine the nucleation rate, calculate the Zeldovich nonequilibrium factor and the diffusion coefficient of nuclei, and determine the contribution of elastic stresses to the work of formation of a critical nucleus. The data obtained are compared with classical nucleation theory (CNT). A considerable discrepancy between data of MD simulation and CNT (up to 70 orders in the nucleation rate) has been established. With a satisfactory agreement between theory and simulation in the rate of the nucleus transition through the critical size, an essential discrepancy is observed in the work of formation of a critical nucleus. The neglect of elastic stresses in the nucleation work improves the agreement between the results of theory and simulation. The effect of the size dependence of the surface free energy of a critical nucleus on the work of its formation is estimated.