REACTION-DIFFUSION LATTICE GAS - THEORY AND COMPUTER RESULTS

We report on the study of nonequilibrium ordering in the reaction-diff usion lattice gas. It is a kinetic model that relaxes towards steady s tates under the simultaneous competition of a thermally activated crea tion-annihilation (reaction) process at temperature T, and a diffusion process driven by a heat bath at temperature T' not-equal T. The phas e diagram as one varies T and T', the system dimension d, the relative a priori probabilities for the two processes, and their dynamical rat es is investigated. We compare mean-field theory, new Monte Carlo data , and known exact results for some limiting cases. In particular, no e vidence of Landau critical behavior is found numerically when d = 2 fo r Metropolis rates but Onsager critical points and a variety of first- order phase transitions.