FOKKER-PLANCK EQUATION FOR NONEQUILIBRIUM COMPETING DYNAMIC-MODELS

Nonequilibrium lattice models are characterized by the dependence of t heir stationary properties on the details of their underlying microsco pic dynamic. Any mesoscopic description of these systems, such as a Fo kker-Planck equation (FPE), should reflect this microscopic dependence . In this paper we construct a FPE from a given master equation whose dynamics is a superposition of rates, each one alone driving the syste m to a different equilibrium state. The FPE obtained exactly reproduce s (i) locally the exact stationary nonequilibrium distribution around its extremals and (ii) globally the equilibrium stationary distributio n when only one of the rates is acting. In any case the FPE depends on the analytical form of the microscopic rates.