Enhanced fluctuations in driven lattice gases

Monte Carlo simulations are performed to study the enhanced density fluctuations in a square lattice gas with repulsive first and second neighbour interactions which is driven far from equilibrium by an external field. Regions with excess particles (and holes) travel (in opposite directions) with a velocity dependent on the concentration. In this steady state the power spectra of current-current correlation functions are proportional to ω−13 at low frequencies. This behaviour may be considered as a consequence of the peculiar concentration dependence of conductivity which has a sharp minimum related to the short range ordering.