PLANAR DENSITY-FUNCTIONAL APPROACH TO THE SOLID-FLUID INTERFACE OF SIMPLE LIQUIDS

A planar formulation of the weighted-density approximation is applied to the solid-fluid interface of simple liquids. Computational requirements are reduced from the previous theory through definition of a one-dimensional weighted density that recognizes the planar symmetry of the interface. After finding good agreement with hard-sphere Monte Carlo results, the approach is extended to attractive systems, in particular, the Lennard-Jones fluid. This system provides a stringent test of the model due to its long-range interactions; it is a well-studied example of systems whose density difference varies with temperature. Interfacial tensions are determined for both the solid-liquid and solid-vapor regions of the phase diagram, and reasonable agreement is found with molecular-dynamics simulations at the triple point.