Charged hard spheres in a uniform neutralizing background

Abstract

Monte Carlo computations for the thermodynamic properties and pair distribution function of a one-component system of charged hard spheres in a uniform neutralizing background are compared with perturbation theories. These are the ‘mixed’ integral equation approach proposed by Lado, the exponential approximation of Andersen and Chandler, a higher-order cluster expansion approximation due to Stell and Verlet and Weis and the mean spherical approximation (MSA). It is shown that, while none of these approximations gives satisfactory results for the pair distribution function, both the MSA and the mixed integral equation approach give internal energies in excellent agreement with the Monte Carlo results.