The influence of long-range force truncation on the thermodynamics of aqueous ionic solutions

Abstract

The extended‐RISM integral equation, with a renormalized HNC closure capable of accounting for truncated ion–solvent interactions, is used to examine the influence of electrostatic truncation on free energies and relative chloride and bromide ions at infinite dilution in SPC water are studied. Large effects in the ion–water distribution functions are observed for truncation distances between 7 and 12 Å. The resulting free energies and relative free energies of hydration display a slight oscillatory behavior as a function of truncation distance, with the maximum deviations occurring for the shortest truncation distances. The observed oscillatory behavior is in qualitative agreement with earlier Monte Carlo and molecular dynamics results.