(51i) Inherent-State Melting and the Onset of Glassy Dynamics in Two-Dimensional Supercooled Liquids

Below the onset temperature, the equilibrium relaxation time of most glass-forming liquids exhibits super-Arrhenius temperature dependence and their relaxation proceeds through localized elastic excitations. Despite its importance in distinguishing the supercooled regime from the high-temperature regime, the microscopic origin of the onset temperature is not yet known. Here, we construct a theory for the onset temperature and find that inherent-state melting, described by the binding-unbinding transition of dipolar elastic excitations, predicts the onset of glassy dynamics in two-dimensional supercooled liquids. The theoretically predicted onset temperature is in good agreement with that found in various two-dimensional glass formers. We finally discuss the predictions of our theory on the displacement and density correlations, which can be understood as a consequence of Mermin-Wagner fluctuations.