Diffusion in a Two-Dimensional System

Abstract

The velocity autocorrelation in a two-dimensional Lennard-Jones system is obtained by the molecular-dynamics method. At moderate densities the autocorrelation function decays slowly, proportional to the inverse time whereas it decays rapidly at high density. The model is compared with monolayers of methane adsorbed on the basal plane of graphite. The influence of the substrate on the diffusion is small and the calculated and experimentally obtained diffusion constants agree at high density.