Minimal current phase and universal boundary layers in driven diffusive systems - art. no. 056110

We investigate boundary-driven phase transitions in open driven diffusive s ystems. The generic phase diagram for systems with short-ranged interaction s is governed by a simple extremal principle for the macroscopic current, w hich results from an interplay of density fluctuations with the motion of s hocks. In systems with more than one extremum in the current-density relati on, one finds a minimal current phase even though the boundaries support a higher current. The boundary layers of the critical minimal current and max imal current phases are argued to be of a universal form. The predictions o f the theory are confirmed by Monte Carlo simulations of the two-parameter family of stochastic particle hopping models of Katz, Lebowitz, and Spohn a nd by analytical results for a related cellular automaton with deterministi c bulk dynamics. The effect of disorder in the particle jump rates on the b oundary layer profile is also discussed.