Dresden 2014 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 4: Glasses (Joint Session with DY and CPP)
DF 4.2: Vortrag
Montag, 31. März 2014, 15:15–15:30, ZEU 146
Understanding the nonlinear mobility of single driven particles in supercooled liquids — •Carsten F. E. Schroer1,2 and Andreas Heuer1,2 — 1WWU Münster, Münster, Germany — 2Graduate School of Chemistry, Münster, Germany
We perform MD simulations of a binary Lennard-Jones mixture where a single particle is pulled by an external field through the liquid. Herein, we are specifically interested in the range of intermediate and strong forces when nonlinear effects occur in the single particle dynamics.
It is known from experimental and simulation studies, that the steady-state velocity v follows in the limit of low forces a linear response relation v=µ F where the force F is connected to the dynamical response via the constant mobility µ0=D0/kB T. For large forces, however, one finds a dramatic increase of v with increasing F, indicating a nonlinear force-dependence of the mobility, i.e. µ0→µ(F).
To gain a deeper understanding of this behavior, we studied the underlying potential energy landscape of the system by computing the minima the system has resided in during its time-evolution. This immediately allows us to discuss the nonlinear mobility in terms of thermodynamical (distribution of energies) and kinetic (escape rates out of single minima) quantities. Most interestingly it turns out, that both effects are of major importance for the nonlinearity of the system, so that there is no single nonlinear effect but an interplay of two independent which contributes to the dynamical responses of the driven particles.