The generalized van der waals partition function. I. basic theory

Sandler, S.I., 1985. The generalized van der Waals partition function. I. Basic theory. Fluid Phase Equilibria, 19:233-257 In this paper we provide a new derivation of the generalized van der Waals partition function for pure fluids and mixtures, and show how this partition function can be used as a basis for understanding equations of state, their mixing rules, and excess free energy (activity coefficient) models. The results presented here clarify some of the confusion which presently exists in the literature concerning the ramifications of local composition thermodynamic models, and provide the theory for papers to follow which combine the generalized van der Waals partition function and our computer simulation results to obtain new, statistical mechanical-based thermodynamic models.