Relaxation in binary mixtures: Non-ideality, heterogeneity and re-entrance

Binary mixtures show many kinds of fascinating dynamical behaviour which has eluded microscopic description till very recently. In this work we show that much of the anomalous behaviour can be explained by building suitable models and carrying out theoretical and simulation studies. Specifically, three well-known problems have been addressed here. (a) Non-ideality in composition dependence of viscosity, (b) re-entrant behaviour of orientational relaxation, and (c) heterogeneity in supercooled binary mixtures. The physical origin of the dynamical behaviour of binary mixtures can be understood in terms of composition fluctuation, a study of which has also been presented in this paper.