NONLINEAR CHEMICAL-DYNAMICS IN LOW DIMENSIONS - AN EXACTLY SOLUBLE MODEL

Restricting space to low dimensions can cause deviations from the mean-field behavior in certain statistical systems. We investigate, both numerically and analytically, the behavior of the chemical reaction A + 2X half arrow right over half arrow left 3X in one and two dimensions. In one dimension, we produce exact results showing that the trimolecular reaction system stabilizes in a nonequilibrium, locally frozen, asymptotic state in which the ratio r of A to X particles is a constant number, r = 0.38, quite different from the mean-field ratio, r(MF) = 1. The same trimolecular model, however, reaches the mean-field limit in two dimensions. In contrast, the bimolecular chemical reaction A + X half arrow right over half arrow left 2X is shown to agree with the mean-field predictions in all dimensions. For both models, we show that the adoption of certain types of transition rules in the laws of evolution can lead to oscillatory steady states.