Monte Carlo Simulation of Solutions of Like-Charged Colloidal Particles

摘要

Model systems of charged spherical macroions possessing 60 elementary charges with either monovalent, divalent, or trivalent counterions interacting solely through hard-core and Coulomb forces have been investigated by Monte Carlo simulations. Eward summation of the long-range Coulomb interactions and cluster moves to improve the macroion mobility were found to be two indispensable techniques for these studies. Although the direct macroion-macroion interaction is purely repulsive, we find that for sufficiently strong electrostatic coupling, there exists an effective attraction that separates the solution into two fluid phases. The attraction is short-ranged and arises from correlations among counterions localized near different macroions. This mechanism for attraction differs from than attraction inferred to operate in solutions of charged latex particles, which is presently challenging the classical DLVO theory.