The integral equation theory for a model 2ndash;2 electrolyte is studied in detail. In this model electrolyte, 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 egr;0in order to model water at 25thinsp;deg;C. The bridge function for this model is studied as a function of concentration (a) for six proposed closures, and (b) via lsquo;lsquo;exactrsquo;rsquo; 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 lsquo;lsquo;optimizedrsquo;rsquo; longhyphen;range potential, as opposed to the traditional Coulomb choice. A simple functional form for the bridge function results from this optimized choice of longhyphen;range potential.
展开▼
