Long-time self-diffusion of charged Brownian particles: self-friction vs. electrolyte friction

The generalized Langevin equation formalism proposed by Medina-Noyola is used to calculate the long-time self-diffusion coefficient Dsl of charged spherical Brownian particles as function of their charge Q0 and volume fraction ϕ, and of the salt concentration ns. The effects of self-friction and of electrolyte friction are considered simultaneously. The combined action of the Debye–Hückel screening of the interparticle interaction potential and of the electrolyte friction is found to result in a non-monotonic behavior of Dsl as function of ns, for typical values of ϕ and Q0.