Monte Carlo simulation of cooperative orientation relaxation of dipoles in glass formers

Abstract : The glass transition in dipolar glass formers with long-range indirect dipole-dipole interactions has been studied by Monte Carlo simulation. Our simulation shows that the non-Arrhenien behavior of the relaxation time with temperature is induced by a progressive crossover from a regime of fast dynamics at high temperature in the polar liquid to one of slow dynamics controlled by the presence of polar clusters. The interaction between the clusters results in a spectrum of relaxation time and transition to the glass state. The glass transition starts at a temperature T0>Tc, below which spatial heterogeneities appear. These spatial heterogeneities start to influence the dynamical behavior and the spectrum of relaxation time becomes asymmetric. Below Tc, when the polar clusters reach a nanometric size ergodicity breaking occurs.