Thermodynamics and structure of charged hard-sphere fluids in the mean spherical model

Abstract

The “mean spherical model” (MSM) for an MX-type fluid of charged hard-spheres of different diameters has been solved numerically. The solution method is discussed in detail. The model allows one to examine thermodynamic and structural properties of charged hard-sphere fluids in a wide range of density and temperature and over the whole range of radius ratio. Internal energies and state equations are discussed while a broad picture of the structure is given through extensive results for the pair correlation function. The partial structure factors for which the model provides analytic expressions, are compared with available experimental and computer simulation data for molten sodium and potassium chloride. The agreement obtained is generally encouraging and almost quantitative when the ionic radii are chosen by fitting the experimental compressiblities.