Comparison of Brownian dynamics with photon correlation spectroscopy of strongly interacting colloidal particles

The Brownian dynamics computer simulation method is applied to a dilute system of charged spheres dispersed in a very dilute electrolyte. The parameters of this model system are chosen to match those of an aqueous dispersion of highly charged and strongly interacting polystyrene spheres, on which a number of photon correlation spectroscopy studies have recently been made. The structure factor and the electric field autocorrelation functions calculated by the Brownian dynamics method agree with the experimental data provided that allowances are made for the effects of polydispersity and multiple scattering. A few commonly used approximations for analyzing the dynamic properties of many particle systems are also examined.