Size correlations in colloidal suspensions

We study the effect of correlations due to hardcore effects in the distribution of ions around a spherical macroion enclosed in a limited cell. The osmotic pressure is also computed. Both the profile and the pressure are obtained within density functional approaches. Various recipes for the correlations are compared with the Poisson Boltzmann analysis. In the regime of low ionic strength and ionic radius that is not too large, the weighted density functionals based on the Percus–Yevic and the Carnahan–Starling approaches seem to incorporate the size correlations better than the similar local density prescriptions do.