Nonequilibrium phase transitions in a simple three-state lattice gas.

We investigate the dynamics of a three-state stochastic lattice gas consisting of holes and two oppositely “charged” species of particles, under the influence of an “electric” field at zero total charge. Interacting only through an excluded-volume constraint, particles exchange with holes and, on a slower time scale, with each other. Using a combination of Monte Carlo simulations and meanfield equations of motion, we study a set of suitably defined order parameters, their histograms and fluctuations, as well as the current through the system. With increasing particle density and drive, the system first orders into a charge-segregated state, and then disorders again near complete filling. The transition is first order at low densities and turns second order at higher ones. The finite-size and aspect-ratio dependence of characteristic quantities is discussed at the mean-field level. [ABSTRACT FROM AUTHOR]