A rescaled MSA structure factor for dilute charged colloidal dispersions

The structure of a dispersion of charged colloidal particles interacting through a screened Coulomb potential is well described at moderate to high densities by calculating the correlations in the mean spherical approximation (MSA). In this paper we extend the validity of the MSA calculation to arbitrarily low densities, using a physical rescaling argument which preserves the analytic form of the MSA solution. Our results are in excellent agreement with other numerical calculations and with experimental low-density light scattering data. The method may be viewed as a generalization of Gillan's prescription for one component plasmas to systems interacting through a Yukawa potential. An advantage of the present prescription is that it allows a smooth transition from strong to weak coupling, and it implies no functional relation between the experimentally independent parameters.