Activated Dynamics and the Ergodic-Nonergodic Transition

The hindered diffusion model is introduced. It is a continuum model giving the dynamics of a conserved density. Similar to the spin-facilitated models, the kinetics are hindered by a fluctuating diffusion coefficient that decreases as the local density approaches some geometrically constrained value where the mobility goes to zero. The model leads in a natural way to activated dynamics at low temperatures and high densities. In a well defined approximation the theory is shown to be compatible with mode-coupling theory. Indeed in the simplest form of the model we find an ergodic-nonergodic transition into a phase that supports activated kinetics and nonergodic behavior.