A generalised Landau theory for chemical instabilities

Abstract

A generalised Landau theory for non-equilibrium phase transitions in chemical reactions is developed. This theory is based on the construction of a generalised free energy which describes just the fluctuations in excess of equilibrium. This is accomplished most readily via the Poisson representation. This theory yields results for the spatial correlation function in agreement with those of the stochastic master equation. The range of validity of the Landau theory and the Gaussian approximation to the master equation are found to be equivalent and both are shown to yield satisfactory results for nonequilibrium chemical phase transitions.