Non-polar solute-water pair correlation functions

The microscopic theory of the solvation of non-polar solutes in water proposed by Pratt and Chandler has been generalized in order to obtain separate solute-oxygen and solute-hydrogen radial distribution functions, g(r). The g(r)s predicted by this method for a spherical solute have been tested by comparison with the corresponding functions from two computer simulation studies. The water-water interactions were described by the configuration intereaction potential (CI) in both cases. The agreement between theoretical and simulation results is good for the solute-oxygen g(r), less so for the solute-hydrogen function. Moreover, the influence of the model of water on the calculated solute-solvent g(r)s has been examined by comparing results obtained with partial structure functions derived from the CI model and from recent neutron diffraction measurements. It is found that CI model and real water yield remarkably different solute-water radial distribution functions. Finally, the solvation of a model two-site solute has been studied for various bond lengths and the results confirm that when the space between the sites is sufficient to host a water molecule, the solvation of each site is the same as that of an isolated site, with respect to oxygen as well as hydrogen.