A simple physical picture of liquid–glass transition

We demonstrate here a simple physical picture of liquid–glass transition, which qualitatively explains most of the dynamic features from the strong-glass to the fragile-glass limit. We classify the dynamic environment of a molecule into loose and tight cages. Glass transition is then characterized by two transitions: (i) the appearance of tight cages at the crossover temperature Tc and (ii) the disappearance of loose cages at the Vogel–Fulcher temperature T0. We propose that the fragility of glass is strongly correlated with the relative importance of the topological confinement against the anisotropic attractive intermolecular interactions for the formation of tight cage.