EXCLUDED-VOLUME ANISOTROPY AND 2-CAVITY DISTRIBUTION-FUNCTIONS IN HARD-SPHERE FLUIDS

A new model for the distribution of spherical cavity pairs in a hard s phere fluid is derived by extending exact low density results to inclu de the effects of cavity pair anisotropy at finite solvent density. In particular, the unitless excluded surface-area-to-volume ratio is use d to quantitate the anisotropy dependence of the excess chemical poten tial of a solute cavity pair. The Carnahan-Starling contact radial dis tribution function of a single component hard sphere fluid is used to fix this anisotropy dependence. Predictions of the resulting excluded volume anisotropy (EVA) model for the two-cavity distribution function are found to compare favorably with previous simulation and analytica l results. Generalization of the EVA model to predict solvation thermo dynamics of arbitrary shaped solutes in molecular liquids, as well as multi-cavity distribution functions in hard sphere fluids are suggeste d. (C) 1997 American Institute of Physics.