Grand canonical stochastic potential for ordering and phase coexistence in driven systems

For a kinetic Ising model with two competing dynamics, applied to an AB alloy, we build a mean-field grand canonical potential which governs the steady-state probability distribution of the concentration and long-range order parameter. We then compute the dynamical equilibrium phase diagram for a driven body-centered-cubic alloy with negative mixing enthalpy (analogous to an antiferromagnet) and predict an induced phase coexistence for B2 ordering.