title: Nonadditivity in the effective interactions of binary charged colloidal suspensions.
abstract: Based on primitive model computer simulations with explicit microions, we calculate the effective interactions in a binary mixture of charged colloids with species A and B for different size and charge ratios. An optimal pairwise interaction is obtained by fitting the many-body effective forces. This interaction is close to a Yukawa (or Derjaguin-Landau-Verwey-Overbeek (DLVO)) pair potential but the AB cross-interaction is different from the geometric mean of the two direct AA and BB interactions. As a function of charge asymmetry, the corresponding nonadditivity parameter is first positive, then significantly negative and is then positive again. We finally show that an inclusion of nonadditivity within an optimal effective Yukawa model gives better predictions for the fluid pair structure than DLVO theory.
authors.affiliation: Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany. Department of Physics, Case Western Reserve University, Cleveland, OH 44106, USA. Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow, Russia.
authors.forename: E
authors.initials: E
authors.lastname: Allahyarov
authors.forename: H
authors.initials: H
authors.lastname: Löwen