Phase transitions in stationary nonequilibrium states of model lattice systems

We investigated the stationary nonequilibrium states of a lattice gas of interacting particles subject to an external field 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 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 E. We found evidence for a transition line in the temperature-field plane at which the system develops (anisotropic) long-range order. E enhances the transition for attractive interactions and represses it for repulsive ones.