CALCULATION OF THE STATIC DIELECTRIC-CONSTANT OF MULTIPOLAR MIXTURES BY PERTURBATION-THEORY - AN APPLICATION TO SUPERCRITICAL WATER-BENZENE MIXTURES

Second-order perturbation theory for the molecular pair correlation function, together with a gamma-expansion of the static dielectric constant (epsilon) is used to predict and interpret epsilon for supercritical benzene-water mixtures. Our predictions are compared directly with experimental results. We find that this approach, which was previously found successful provided gamma < 3 for near multipolar fluids, is also successful here in predicting the excess mixture dielectric constant, Delta epsilon. The results are quantitative to semi-quantitative in accuracy depending slightly on the model chosen and the composition of the mixture. No adjustable parameters were used. We interpret our results in terms of underlying molecular clusters, and make a comparison with the predictions of another (non-molecular) theory.