Self-diffusion of colloids at freezing

This is an introduction to the theory of interacting Brownian particles, as applied to charge-stabilised colloidal suspensions near their equilibrium liquid-solid transition. The density functional approach to the statics of the transition is reviewed briefly, and the generalised Langevin equation method for the dynamics presented in detail. Work with A.V. Indrani [1] on a self-consistent approach for calculating the excess single-particle friction is presented, which explains the observed [2] ''universal'' suppression of self-diffusion at freezing as a consequence of the universal structure-factor height at this transition. Criticisms, open questions, and challenges to theory are discussed.