Molecular dynamics investigation of the premelting effects of Lennard-Jones (111) surfaces

Molecular dynamics simulations have been performed to study the premelting effects of noble-gas surfaces (argon) close to but below the bulk melting temperature. In particular, the increase of disorder as a function of temperature at (111) surface has been considered. The truncated Lennard-Jones (6-12) potential is used to describe the interactions between particles. Surface premelting has been analyzed by means of total energies, trajectory plots, mean sequare displacement functions, diffusion coefficients, vacancy concentrations and two-dimensional order parameters. The (111) surface starts to disorder by vacancy formation, which leads to the premelting of the surface layer far below the bulk melting temperature. Melting proceeds via a layer-by-layer mechanism, when temperature is further increased. This study supports the earlier observations of a melting that proceeds in the direction of high packing density.