Sampling large deviations of mobility and its application to glassy dynamics

A major challenge in the computational sciences is the accurate sampling of events that are rare and have a low probability. Consequently, a wealth of advanced numerical methods devoted to this purpose has been developed. I will review the use of transition path sampling techniques to sample fluctuations of the single particle mobility in trajectories of a model glass former. In the supercooled regime, the dynamics is characterized by correlations that are trivial in space but highly non-trivial in time. There is numerical evidence for a dynamic phase transition from liquid to a jammed glass, which can be probed through a structural order parameter. I will present numerical and experimental results
on the coexistence of the normal supercooled liquid with a phase that is rich in locally favored structures and dynamically arrested. Most strikingly, the coexistence region narrows as temperature is decreased, with the possibility that coexistence terminates at a finite temperature in a lower critical point. I will briefly discuss consequences for our understanding of the glass transition.