On the importance of many-body interactions in the effective fluid model of asymmetric hardsphere mixtures

Comparison of solute pair distribution functions in the true mixture and in the effective fluid is used as a diagnosis of the importance of many-body interactions in the effective fluid model of binary asymmetric hard-sphere mixtures. Results from integral equations and density functional theories are compared with simulation data for size ratios R = 3.33, 10 and 20. Small deviation from the pair interaction approximation are detected up to R = 20. The origin of these deviations suggests that many-body effects might be more important in non-hard-sphere mixtures exhibiting long range solute-solvent correlations.