An extended RISM study of simple electrolytes: pair correlations in a NaCl-SPC water model

Abstract

We have used the extended RISM approach in conjunction with the SPC model of water to compute the ten-pair correlation functions of aqueous NaCl systems in a wide range of salt concentrations (0–5 m). The numerical results are tested against experimental neutron scattering data and computer simulations wherever the latter are available and/or feasible. Overall the positions of the structural features in the correlation functions are reproduced quite well by the computation but other details such as some peak heights and the ion water coordination numbers obtained are less satisfactory. We discuss several problems encountered due to the assumptions inherent in the extended RISM approach one of which is the incorrect dielectric screening behaviour of this theory.