Regensburg 2013 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Glasses II (joint session DY/DF/CPP)

CPP 17.5: Vortrag

Dienstag, 12. März 2013, 10:30–10:45, H46

Microrheology on supercooled liquids in terms of a Potential Energy Landscape approach — •Carsten Friedrich Erich Schroer and Andreas Heuer — Westfälische Wilhelms-Universität Münster, Münster, Germany

We perform MD simulations of a binary Lennard-Jones mixture where an external force is applied on a single tracer particle. The dynamics of the tracer particle includes several interesting features like non-linear mobilities and anomalous diffusion parallel to the force direction. Our main focus relies in the investigation of the underlying Potential Energy Landscape (PEL), especially in the energetic minima the system explores during its time evolution. Equally to equilibrium systems a coarse graining of these minima to mesoscopic regions allows the description of the system dynamics in terms of a continuous time random walk (CTRW). Extending the concept of the CTRW towards stationary non-equilibrium systems turns out to be an efficient tool for the understanding of non-equilibrium dynamics. First, the approach contains a decomposition between linear and non-linear effects, thus enables a detailed study of the transition between these dynamical regimes. Second, it allows the quantitative understanding of the anomalous diffusion of the tracer particle. Third, for the first time a connection between the non-Gaussian parameter α₂ in equilibrium and superdiffusivity in non-equilibrium can be established. With the help of the underlying PEL, important information can be gained about the dynamics, e.g. about the onset of non-linear effects. The non-linear regime can be discussed in terms of a rejuvenation scenario.