- Conference date: 2–7 December 2012
- Location: Sendai, Japan
We study the dynamics of glass-forming systems in terms of the statistics of their waiting times. For small glassforming systems their distributions can be obtained from the analysis of the potential energy landscape. The waiting times refer to the times between metabasin transitions. Whereas the dynamics of small systems is very well understood in terms of the potential energy landscape we consider two ways to complicate the dynamics. First, we study the impact of external forces on a single tagged particle. This corresponds to the microrheological case. We study the resulting mean square displacement in the moving coordinate frame. Depending on the underlying waiting time distribution one may observe superdiffusive, diffusive, or subdiffusive behavior for intermediate times. The short-time and long-time limit can be calculated analytically. Beyond this interesting non-standard behavior one also observes non-linear response at large forces as reflected by a reduction of the average waiting time. More generally, the waiting time distribution experiences a systematic shift to shorter times. Furthermore, we relate the real-space trajectory to the actual transitions between metabasins and inherent structures of the potential energy landscape. Second, we discuss the effect of increasing the system size. Again, one observes a significant variation of the waiting time distribution. This effect can be rationalized in terms of the Coupled Landscape Model (CLM). In contrast to the application of an external force the effect of increasing the system size keeps, however, the first moment of the waiting time distribution constant.
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