Towards a quantification of disorder in materials: Distinguishing equilibrium and glassy sphere packings

The prospects for quantifying disorder in simple molecular or colloidal system is examined. As a central element in this task, scalar measures for describing both translational and bond-orientational order are presented. These measures are subsequently used to characterize the structures that result from a series of molecular-dynamics simulations of the hard-sphere system. The simulation results can be illustrated by a two-parameter ordering phase diagram which indicates the relative placement of the equilibrium phases in order-parameter space.