A 2-DIMENSIONAL GLASS - MICROSTRUCTURE AND DYNAMICS OF A 2D BINARY MIXTURE

A 2D equimolar binary mixture of r(-12) soft disks with a diameter rat io of 1.4 is shown, via constant pressure-temperature molecular dynami cs simulations, to exhibit, on cooling, a wide range of properties of glass-forming liquids. At all temperatures studied, the liquid is foun d to be kinetically stable with respect to crystallisation over time s cales many times that of the structural relaxation. The temperature at which the 'step' in the incoherent scattering function first appears is identified as an important crossover in relaxation mechanisms. Cool ing below this temperature results in the development of kinetic heter ogeneity and the breakdown in scaling between the structural relaxatio n time and the diffusion constant. Direct visualisation provides a mea sure of increasing cooperativity and insight into the nature of the co llective motions. (C) 1998 Elsevier Science B.V. All rights reserved.