Transverse Collective Modes of Supercooled Liquids Obtained from Stress and Current Correlators

A supercooled liquid is a disordered aperiodic system of atoms obtained by rapidly freezing a viscous liquid. One distinguishing characteristic of a supercooled liquid is the tendency of atoms to be trapped by their nearest neighbors engendering a long relaxation time. Several dynamic variables exhibit the extended relaxation process. In this work, we employ atomistic simulations on model glass forming liquids to investigate the shear stress correlations and the attendant relaxation behavior. A range of spatial and temporal scales is probed by analyzing the stress correlations at small, medium and large wavevectors; in the long wavelength limit, the integral of the shear stress correlation (SSC) function provides the shear viscosity. At short wavelengths, the SSC function behaves similar to a normal liquid; from our simulations we draw out the caging effect that results in extended relaxation at longer wavelengths. We also compute the shear viscosity at finite wavelengths through the hydrodynamic relationship with the transverse current correlation (TCC) function. The purpose of this presentation is to provide a description of transverse collective modes in supercooled liquids through the SSC and TCC functions at finite wavelengths.