CHEMICAL-POTENTIALS FROM INTEGRAL-EQUATIONS USING SCALED PARTICLE THEORY .1. THEORY

A new method is presented for calculating chemical potentials using integral equation theories. The method uses a multistep charging process which allows attractive and repulsive contributions to the chemical potential to be determined separately. The hybrid mean spherical approximation is used to provide needed correlations about the test particle. A novel application of particle scaling is used to determine the repulsive, or cavity formation contribution to the chemical potential. A formal definition is given for the effective hard core diameter of a softly repulsive solute molecule. A simple Kirkwood charging process is used to determine the attractive, or solvent-solute binding contribution to the chemical potential. The use of an integral equation theory for estimating the test particle correlation functions allows chemical potentials and solvent-solute bindings to be determined in nonideal mixtures at supercritical conditions.