A new method for computing the anisotropic free energy of the crystal-melt interface

Abstract

Based on the classical nucleation theory and the crystal-melt interface kinetic equation, a new method was proposed to compute the anisotropic free energy of the crystal-melt interface. The method stems from the fact that the interface stiffness, instead of the interface free energy, controls the morphologies of nuclei when they are in equilibrium with the surrounding melts. In addition, the interface stiffness has an anisotropy which is an order of magnitude higher than that of the interface free energy, and the anisotropies of these two quantities are related to each other. Mapping out the relation between the curvature radius on the local interface of the nucleus and the equilibrium undercooling temperature during molecular dynamics simulations, we are able to determine the interface stiffness, the interface free energy, and their anisotropy parameters. The new method was used to compute the anisotropy of interface free energy for pure Cu as an example, and the results are in good agreement with the data from experiments and existing simulations.