Dynamic facilitation is a theoretical perspective on the dynamics of glass forming liquids and the glass transition based on the structure of trajectory space.  This structure emerges from spatial correlations of dynamics that appear in many-body systems as they approach nonergodic or jammed states. It is characterized in terms of dynamical heterogeneity, facilitation, and excitation lines.  These features are associated with a novel class of nonequilibrium phase transitions, whose broken symmetries are obscure or absent in spatial structures, but vivid in space-time, or trajectory space.  I will show how these space-time transitions can be revealed and studied by a 'thermodynamics of trajectories' based on large-deviation methods, and discuss how they give rise to fluctuation behaviour characteristic of the glass transition.  While the basic ideas and principles of dynamic facilitation emerged from the study of idealized systems, the essential physical ingredients of effective localized excitations and kinetic constraints can be shown to be present in more realistic liquid models using the tools of transition path sampling.  Time permitting, I will discuss how the facilitation approach can be extended to quantum many-body systems that display glassy dynamic arrest.

Dynamic facilitation view of the glass transition and its  consequences

244th National Meeting (2012)

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