Lattice spin model AB1B2

A spin model is proposed for a physical system possessing two competing sta tes alpha and beta:alpha has a lower internal energy than beta which has a bigger entropy. The model is simulated on a two-dimensional square lattice of 250 x 510 sites with periodic boundary conditions and implemented in a h ardware cellular automata. The algorithm is completely determinist. Lattice simulation results as well as theoretical approaches show that there is a threshold for the surface tension, above which a phase transition occurs; t he transition order is governed by the surface tension. Lattice simulations allowed a precise determination of the AB1B2 model phase diagram. (C) 2000 Elsevier Science B.V. All rights reserved.