VAPOR-LIQUID-EQUILIBRIUM FROM THE PERTURBATION-THEORY OF CONVEX MOLECULE FLUIDS

A first-order perturbation theory of molecular fluids is used to determine the excess thermodynamic functions of binary systems whose molecules interact via the Kihara core pair potential. A reference system of soft convex bodies is characterized by properties of representative hard convex bodies - parallel convex bodies to the given cores with thicknesses calculated from an analogue to the Barker-Henderson relation for simple fluids. Perturbation integrals are evaluated numerically using a simple approximation for the average correlation function. The excess thermodynamic functions were evaluated at pressure P → 0 and compared with experimental values of four binary systems. From the concentration dependence of ΔGE, the x-y diagram was determined. © 1979.