Effect of triplet attractions on the phase diagram of suspensions of charged colloids

We study, by simulation, the effect of attractive triplet interactions on the phase behaviour of suspensions of charged colloidal particles at low ionic strength, i.e. in the regime where the pair interactions are purely repulsive. We use the pair and triplet interactions that were obtained recently from a numerical, nonlinear Poisson–Boltzman study (Russ et al 2002 Phys. Rev. E 66 011402). Our simulations tentatively explain, for the first time, experimental observations of a rather large density difference between coexisting body centred cubic and face centred cubic crystal phases.