Regensburg 2010 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 3: Complex energy landscapes (addendum to SYEL)
DY 3.1: Talk
Monday, March 22, 2010, 14:00–14:15, H42
Coupling in glass-forming systems: From MD simulation to generalized KCM models — •Christian Rehwald and Andreas Heuer — Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, 48149 Münster
Macroscopic glass-forming systems can be regarded as superposition of coupled elementary units, whose dynamics can in turn be described within the framework of the potential energy landscape and the concept of metabasins. This treatment of supercooled liquids leads to “coupled energy landscapes” for which we present a different concept to describe this coupling.
We study a binary mixture Lennard-Jones liquid for different system sizes and calculate local waiting times generated by particle displacements to gain detailed information about coupling events. While the waiting time distributions of local exchange events can be used to measure the coupling strength, the identification of the underlying processes requires greater effort. For this purpose we use the iso-configurational ensemble of a suitably prepared configuration to understand in detail the response to a single local relaxation event. Furthermore, we work out the essential differences between strong and weak coupling.
These MD results can be used to define a generalized KCM model. It turns out that the model can reproduce many properties of glass-forming systems, e.g. different finite size effects of D and τα or the growth of dynamical length scales (χ4).