Johari-Goldstein Relaxation Events Are Metabasin Transitions

We show that by representing quasi-elastic and inelastic neutron scattering from propylene carbonate (PC) with an explicitly heterogeneous model, we recover two distinct dynamic signatures in addition to diffusive motion. The intermediate scattering function provides access to the time-dependence of these two dynamic processes, and they appear to correspond to transitions between inherent states and between metabasins on a potential energy landscape. By fitting the full q-dependence of inelastic scattering, we confirm that that the Johari-Goldstein ($\beta_{JG}$) relaxation in PC is indistinguishable from metabasin transitions.