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 phi, 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 phi and T. The former is essentially vertical (phi controlled), while the latter is rather horizontal (T controlled) in the (phi-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.
Mode-coupling theory predictions for a limited valency attractive square well model
E Zaccarelli;E La Nave;F Sciortino;
2006
Abstract
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 phi, 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 phi and T. The former is essentially vertical (phi controlled), while the latter is rather horizontal (T controlled) in the (phi-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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.