The structure and thermodynamics of a solid–fluid interface

Abstract

The structure and thermodynamics of a solid–fluid interface are examined for systems of Lennard-Jones particles by performing molecular-dynamics calculations. Two sets of calculations have been carried out for systems of 952 particles adjacent to surfaces with and without lattice structure. The lattice structure is taken to be one (111) surface of a face-centred cubic crystal of Lennard-Jones particles. The calculations are performed for different pressures corresponding to dense fluid states at a temperature above the critical temperature.

The stratified interface is found to consist of only a few (4–5) layers even at high pressure. The thickness of the interface increases continuously with pressure and the profile is insensitive to the structure of the solid surface. Only a small amount of lattice order is found in the interface and then only in the contact layer directly at the lattice surface. The excess thermodynamic functions, e.g. the surface tension, however, are found to be affected by the particle and lattice structure of the surface.