Asymmetric binary mixtures with attractive forces: towards a quantitative description of the potential of mean force

The potential of mean force for macroparticles at infinite dilution is computed for several models of solvent-solvent and solvent-macroparticle interactions. The reference hypernetted-chain (RHNC) closure of the integral equations for the distribution functions is used. The bridge functions taken from Rosenfeld's density functional theory are computed for the special case of macroparticles at infinite dilution. This method is found to significantly improve upon previous calculations as regards the agreement with simulations. In the few cases where the agreement is semi-quantitative, possible improvements such as going beyond the second-order expansion of the attractive part of the free-energy functional are suggested.