MOLECULAR-DYNAMICS SIMULATIONS OF A CHEMICAL WAVE-FRONT

A periodically expanded molecular dynamics technique for reactive hard spheres is applied to simulate a propagation of a chemical wave front in a closed system with a model reaction A + B --> A + A. The results of simulations are compared with the theory based on the standard, pa rabolic reaction-diffusion equation. It is found that a front propagat es with a speed which is higher than the minimum stable one and that t he speed scaled by the square root of the rate constant k is an increa sing function of k. This effect may be explained if separated equation s for concentration of A and for the associated diffusive flow are con sidered. The case in which the reaction is thermally activated, is als o studied. The influence of nonequilibrium effects on the shape of a c oncentration profile and on the front speed are discussed.