Phase transitions in stationary nonequilibrium states of model lattice systems

Abstract

We investigated the stationary nonequilibrium states of a lattice gas of interacting particles subject to an external field $\stackrel{\ensuremath{\rightarrow}}{E}$. The dynamics of the system are given by hoppings of particles to nearby empty sites with rates biased for jumps in the direction of $\stackrel{\ensuremath{\rightarrow}}{E}$. This system is often used to model fast ionic conductors. Using computer simulations of a two-dimensional lattice with nearest-neighbor interactions we studied the dependence of the structure function, current, etc., on temperature and $\stackrel{\ensuremath{\rightarrow}}{E}$. We found evidence for a transition line in the temperature-field plane at which the system develops (anisotropic) long-range order. $\stackrel{\ensuremath{\rightarrow}}{E}$ enhances the transition for attractive interactions and represses it for repulsive ones.