Two-dimensional two-state lattice-gas model.

We propose a two-dimensional lattice-gas (2D LG) model where atoms may be in two different states: the immobile state, in which they jump as usual in the LG model, and the running state, in which the atoms always jump in the driving direction. The model demonstrates a typical behavior of "traffic-jam" models: the system splits into domains of immobile atoms (jams) and running atoms. We considered four variants of the 2D LG model, namely the multilane and truly 2D models, each with "passive" and "active" atomic jumps. The model has the steady state with a power law distribution of jam sizes characterized by a universal exponent 3/2. The phase diagram of the model shows that the mobility of the 2D system is lower than the mobility of the 1D model due to the spreading of jams in the direction transverse to the driving direction.