Effect of colloidal charge discretization in the primitive model

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  • 30 June 2000
Abstract
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 \textit{discrete} charges randomly on the sphere. We use molecular dynamics simulations to study this effect on some properties such as overcharging, counterions distribution and diffusion. In the vicinity of the colloid surface the electric field may considerably differ from the one obtained with a central charge. However, we find that the counterion distribution is \textit{qualitatively} not affected, provided that the macroion charge distribution is not strongly inhomogeneous. This leads to the conclusion that, from an electrostatic point of view, the central macroion charge approximation is excellent, as long as surface roughness is neglected.

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