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Soft Matter and Biological Physics

Eur. Phys. J. E 4, 363-370

Effect of colloidal charge discretization in the primitive model

R. Messina, C. Holm and K. Kremer

Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany


(Received 30 June 2000 and Received in final form 28 November 2000)

The effect of fixed discrete colloidal charges in the primitive model is investigated for spherical macroions. Instead of considering a central bare charge, as it is traditionally done, we distribute discrete charges randomly on the sphere. We use molecular dynamics simulations to study this effect on various properties such as overcharging, counterion distribution and diffusion. In the vicinity of the colloid surface the electrostatic potential may considerably differ from the one obtained with a central charge. In the strong Coulomb coupling, we showed that the colloidal charge discretization qualitatively influences the counterion distribution and leads to a strong colloidal charge-counterion pair association. However, we found that charge inversion still persists even if strong pair association is observed.

82.70.Dd - Disperse systems: Colloids.
61.20.Qg - Structure of associated liquids: electrolytes, molten salts, etc..
41.20.-q - Applied classical electromagnetism.

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001