Collective diffusion of lattice gases in disordered lattices in the absence of a single-particle diffusion coefficient

Abstract

Collective diffusion of particles is studied in a three-dimensional lattice-gas model with site-energy disorder. The distribution of the site energies is exponential, and the diffusion coefficient of independent particles may vanish. It is demonstrated by numerical simulations that a coefficient of collective diffusion exists. An estimate of the diffusion coefficient for smaller particle concentrations suggests a power-law dependence on concentration, consistent with the simulations. An effective-medium calculation of the coefficient of collective diffusion gives good agreement with the data at smaller particle concentrations and rough agreement at larger concentrations.