Solute-solute potential of mean force for non-polar molecules in water

Abstract

A recently proposed extension of the Pratt-Chandler (PC) theory of the hydration of non-polar solutes has been applied to the calculation of solute-solute radial distribution functions, gaa (r)s. The difference between results obtained with the original and extended PC method is studied for solutes interacting with water through purely repulsive or full Lennard-Jones potentials. The role of the model of water on the calculated gaa (r) has been examined, for both the above interactions, comparing results computed with partial structure functions derived from computer simulation and neutron diffraction measurements. It is found that the model of water affects gaa (r) more than solute-water attractive forces. Finally, the size dependence of gaa (r) has been discussed with both PC methods and the results are qualitatively different for the largest solute considered, a Lennard-Jones model of neopentane. In particular, the contact configuration is excluded by the new approach and accepted by the original one.