Density-functional theory and atomistic simulation of the hard-sphere melt-solid interface.

Abstract

The melt-solid interface of hard spheres is studied by atomistic simulations and density-functional theory (DFT). The Monte Carlo method is used to compute density profiles for the three most important orientations of the fcc-solid--melt interface. The interface ranges in thickness from 4d for the loosely packed (110) interface to 6d for the closely packed (111) interface, where d is the hard-sphere diameter. The planar generalized effective liquid approximation (PGELA) free energy functional, which accurately predicts solid and liquid free energies and coexistence conditions, is used in the DFT analysis of the hard-sphere melt-solid interface. Two parametrizations are compared for variations of the density in the interfacial region. The structural predictions of the interface by the Carnahan-Starling PGELA are in good agreement with the simulations. The calculations of the surface free energies show that the (110) interface has a smaller surface free energy, followed by the (100) interface and then closely by the (111) interface. These results are compared to other recent studies of the hard-sphere melt-solid interface.