Integral equation theory for charged liquids: Model 2–2 electrolytes and the bridge function

Publisher Website
Google Scholar
Abstract
The integral equation theory for a model 2–2 electrolyte is studied in detail. In this modelelectrolyte, the ions are assumed to be the same size, and interact via a continuous potential energy which behaves as the Coulomb potential at large distances and an inverse ninth power repulsion at short distances. The ions are embedded in a dielectric continuum of fixed dielectric constant, here taken to be 78.3 ε0 in order to model water at 25 °C. The bridge function for this model is studied as a function of concentration (a) for six proposed closures, and (b) via ‘‘exact’’ inversion of data from computer simulations. A proposed closure derived from examination of the inverted bridge function yields predictions in good agreement with computer simulations. We emphasize the importance of choosing an ‘‘optimized’’ long‐range potential, as opposed to the traditional Coulomb choice. A simple functional form for the bridge function results from this optimized choice of long‐range potential.