A DYNAMICAL MODEL OF SUPERCOOLED LIQUIDS

A dynamical theory of supercooled liquids is constructed by generalizi ng the Maxwell model of viscoelasticity in which the time-dependent st ress and strain tensors are endowed with additional spatial dependence . A further important input is a local orientational order parameter t hat characterizes the local cages in a dense liquid. The tendency of t he system to order orientationally is shown to lead to enhancement of the viscosity near a calculable temperature, T-G, which is identified as the glass transition temperature. The kinetics of the orientational order parameter, associated with structural relaxations, are shown to have an influence on the hydrodynamic current and density modes and h ence on the experimentally measured quantities, e.g., the dynamical st ructure factor, depolarized light scattering, etc.