Mode-coupling theory predictions for a limited valency attractive square well model

Recently we have studied, using numerical simulations, a limited valency model, i.e. an attractive square well model with a constraint on the maximum number of bonded neighbours. Studying a large region of temperatures T and packing fractions ϕ, we have estimated the location of the liquid–gas phase separation spinodal and the loci of dynamic arrest, where the system is trapped in a disordered non-ergodic state. Two distinct arrest lines for the system are present in the system: a (repulsive) glass line at high packing fraction, and a gel line at low ϕ and T. The former is essentially vertical (ϕ controlled), while the latter is rather horizontal (T controlled) in the (ϕ–T) plane. We here complement the molecular dynamics results with mode coupling theory calculations, using the numerical structure factors as input. We find that the theory predicts a repulsive glass line—in satisfactory agreement with the simulation results—and an attractive glass line, which appears to be unrelated to the gel line.