The molecular basis for local compositions in liquid mixture models

Abstract

The local-composition concept is examined critically. When a general local-composition model is subjected to different constraints, we obtain different forms, corresponding to those presented earlier in literature. For simple mixture, a physically meaningful constraint gives a one-parameter model whose properties are obtained from the Lennard-Jones potential. For this model, the calculated excess Helmholtz energy and calculated local compositions are in good agreement with results from Monte Carlo data and with results from perturbation theory, recently reported by Nakanishi et al. © 1983.