Elementary excitations and the specific heat peak in a supercooled mixture: simulation studies

Abstract We report on the existence of a peak in both CP and CV in simulation studies of a 2D glass-forming mixture of soft disks. We present evidence that this feature represents an equilibrium property of the supercooled liquid. To establish what degrees of freedom are associated with this anomalous heat capacity, we have resolved the instantaneous potential energy into that due to the local minimum (identified through a conjugate gradient quench) and the residue. We demonstrate that the peak in CV arises due to fluctuations between different local minima. We have examined the spatial distribution of the energy change between adjacent minima and demonstrate that, at low temperatures, the fluctuations in energy involve reasonably compact clusters of particles. The particles in these clusters are not necessarily the same as those involved in large amplitude displacements.