On the Grier−Crocker/Tata−Ise Controversy on the Macroion−Macroion Pair Potential in a Salt-Free Colloidal Suspension

Abstract

Several aspects of a recent controversy between the groups of Grier and Crocker [Crocker, J. C.; Grier, D. G. Phys. Rev. Lett. 1994, 73, 352; 1996, 77, 1897. Grier, D. G.; Crocker, J. C. Phys. Rev. E 2000, 61, 980.] and Tata and Ise [Tata, B. V. R.; Ise, N. Phys. Rev. E 1998, 58, 2237; 2000, 61, 983.] over experimental data vis-a-vis the appropriateness of the classical Derjaguin−Landau−Verwey−Overbeek screened Coulomb pair potential versus the Sogami−Ise pair potential with an “attractive tail” in a charge-stabilized colloidal suspension are discussed. In particular, the relevant and sometimes contentious issue of the interrelationship between the effective colloid charge Zeff and the effective Debye−Huckel screening parameter κeff is explored. Through a screened Coulomb analysis of Monte Carlo (MC) simulations of an isolated colloidal particle and its ion cloud, it is seen that the effective charge and the effective screening parameter remain essentially uncorrelated in practice. Examination of the unde...