The concept of mean free path in the kinetic Monte Carlo description of bulk fluid behaviour, vapour-liquid equilibria and surface adsorption of argon

Recently, kinetic Monte Carlo (kMC) simulation has been successfully applied to describe bulk fluid behaviour, vapour-liquid equilibrium and adsorption on a graphite surface [Ustinov and Do, J. Colloid Interf. Sci. 366(1) (2012), pp. 216-223]. Its advantage over Metropolis-MC lies in the excellent sampling of the energy space for the direct determination of the chemical potential. In this paper, we address the mechanics of the displacement of a particle, which is the only step in kMC. By invoking the mean free path (MFP) concept and the average travel distance, we establish the connection between the particle sampling of the volume space and the distance of travel of the particle related to the MFP through the Beer-Lambert law. We apply this procedure to vapour-liquid equilibrium in bulk fluid argon and to adsorption of argon on a graphite surface, and demonstrate that the results are entirely consistent with previous simulations.