Surface melting: A density functional approach

A microscopic theory of surface melting is described and applied to Lennard‐Jones systems. Our approach is based on density functional theory with the hard sphere fluid as a reference system. In particular we use a weighted density approximation which yields an accurate Lennard‐Jones bulk phase diagram. Within a practically free minimization of the functional, we find surface melting of a Lennard‐Jones crystal for different surface orientations. Furthermore the hard‐sphere crystal‐fluid interface and the hard‐sphere crystal at a hard wall are explored with density functional theory. It is found that the crystal‐fluid surface tension of hard spheres is extremely small and that the hard wall prefers to be covered by a hard‐sphere‐solid at solid‐liquid coexistence.