A molecular dynamics study of the equilibrium relaxation for inhomogeneous systems

Abstract

Using the method of molecular dynamics, we have analysed the relaxation towards equilibrium of an inhomogeneous and isolated system whose constituent particles interact through a Lennard-Jones potential. The initial velocity distribution is of the type leading to the overpopulation effect observed by Tjon. The initial particle number density is uniform but there is a kinetic energy gradient. It has been observed that the tendency to homogeneization of the kinetic energy induces the presence of a gradient in density, in such a way that successive inhomogeneities show up in both quantities, till equilibrium is finally reached. Furthermore, we observe an overpopulation effect for low and high speeds, analogous to the one reported in a previous work. The time scale characterizing the relaxation of the velocity distribution function is much smaller than that of the tendency of the system towards homogeneity.