The application of the replica ornstein-zernike methodology for studying ionic membrane equilibria.

The applicability of the replica Ornstein-Zernike (ROZ) method, often used to explore the partly quenched systems, for studying ionic equilibria in membrane-like systems was investigated. A simple +1:-1 electrolyte solution was modelled as a primitive model electrolyte on the McMillan-Mayer level of approximation. The particles mimicking membrane were modelled as permeable hard spheres frozen in space in their positions. The ion-membrane potential was chosen to conform as closely as possible to the experimental data. The density profiles of ions near the membrane, as well as adsorption isotherms, were calculated using the ROZ equations complemented by the hypernetted chain (HNC) approximation. The method provides reasonable results in qualitative agreement with experimental observations.