Lattice field theory for spherical macroions in solution: Calculation of equilibrium pair correlation functions

Abstract

A recently developed lattice field theory (LFT) formulation of the statistical mechanics of a classical Coulomb gas interacting with a fixed charge distribution [J. Chem. Phys. 97, 5653 (1992)] is utilized to compute equilibrium pair correlation functions, g(r), of aqueous suspensions of charged spherical macroions (‘‘polyballs’’). These results are compared to the predictions of the widely used Derjaguin et al. (DLVO) theory. In addition an effective pair potential for the colloid–colloid interaction is obtained by applying the LFT approach to a two-colloid system. This pair potential is then used in a many-colloid simulation to obtain g(r). All simulations are performed using the Metropolis Monte Carlo procedure together with the appropriate interpolyball potential function. Even in the regime in which a pair potential description might be expected to be adequate, differences exist between the LFT and pair potential results.