McMillan - Mayer theory for solvent effects in inhomogeneous systems: Calculation of interaction pressure in aqueous electrical double layers

The use of McMillan-Mayer theory to include solvent effects in effective solute-solute interactions for inhomogeneous systems was demonstrated. The approximation of n-body potential of mean force between the ions for cases of large n values by a sum of effective singlet and pair interactions was analyzed. It was also evaluated in presence of all n ions, i.e., at finite concentration. Double layer interaction pressure originating from the interaction between ions dissolved in aqueous electrolyte was calculated. A marked change in the behavior was noticed when there was a tendency for ions to absorb at the surfaces.