A theory for the thermodynamics and structure of nonuniform systems, with applications to the liquid-vapor interface and spinodal decomposition

We propose a theory for the description of the thermodynamics and structure of nonuniform fluids. The theory is based on a generalization of liquid-state perturbation theory of uniform fluids and on the Fisk-Widom generalization of the thermodynamic theory of van der Waals and Cahn-Hilliard. The theory is applied to the liquid-vapor interface near the triple point and near the critical point, and to the thermodynamic analysis of the stability of a single phase fluid in the spinodal region (spinodal decomposition). The limitations of the van der Waals/Cahn-Hilliard theory for surfaces and Cahn's analysis for spinodal decomposition are discussed. Copyright © 1975 American Institute of Physics.