Simulation of diffusion in a two-dimensional lattice gas cellular automaton: a test of mode-coupling theory

Abstract

We compute the velocity autocorrelation function of a tagged particle in a two-dimensional lattice-gas cellular automaton using a method that is about a million times more efficient than existing techniques. A t-1 algebraic tail in the tagged-particle velocity autocorrelation function is clearly observed. The amplitude of this tail is predicted to within a few percent by a lattice-gas version of mode-coupling theory. The magnitude of logarithmic corrections to the t-1 tail is much smaller than expected for continuous fluids.