Deep glassy state dynamic data challenge glass models: Configurational entropy models

There is accumulating evidence that the dynamics of glass-forming systems below the conventional glass transition temperature T_g do not diverge at a finite temperature as conventional extrapolations of the temperature dependence of the dynamics suggest. Here we explore the possibility that theories often interpreted to support this extrapolation may be able to account for the experimentally observed apparent turn-over to a more physically acceptable divergence at zero Kelvin. We examine three different entropy-based glass transition models: the generalized entropy theory (GET), the random first order transition theory (RFOT), and the DiMarzio and Yang model. These are evaluated and compared with the non-diverging deep glassy state dynamic data reported for a 20-million-year-old amber and a vapor deposited ultra-stable amorphous Teflon obtained previously in our laboratories. We make different assumptions about the temperature dependences for configurational entropy for the model evaluations. We find that all configurational entropy models can give non-divergent dynamics with an appropriate configurational entropy and can, then, qualitatively agree with the deep glassy state dynamic data for the ancient amber and the amorphous Teflon. However, all the models still predict somewhat higher relaxation times than the experimentally reported values, which were upper bounds to the equilibrium response.