# Dresden 2009 – wissenschaftliches Programm

## Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

# DF: Fachverband Dielektrische Festkörper

## DF 9: Glass II

### DF 9.3: Vortrag

### Dienstag, 24. März 2009, 14:40–15:00, WIL B321

**How important are facilitation processes for the dynamics in supercooled liquids?** — •Christian Rehwald and Andreas Heuer — Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, 48149 Münster

We investigate a binary mixture Lennard-Jones liquid by molecular dynamics simulation with respect to finite size effects. Our focus is the *q*-dependent relaxation time τ(*q*) and the diffusion constant *D* calculated from particle coordinates, inherent structures and metabasins [1]. It turns out that globally defined metabasins are no longer sufficient to predict *S*(*q*,*t*) for large systems (except for small *q*). In order to avoid this problem, we calculate *local* exchange time distributions, generated by averaged particle displacements [2]. The locally defined distributions show a similar behavior as that of metabasins for long waiting times without depending explicitly on *N*. Moreover, as a result of facilitation processes, increasing the system size leads to a reduction of the long tails of the exchange time distribution. This *N*-dependence is exactly the one expected from a model glass-former based on a set of coupled elementary unit systems [3], which is e.g. implemented in several facilitated spin models.

[1] A. Heuer, Phys.: Cond. Mat. **20** (2008)

[2] L. O. Hedges *et al.*, J. Chem. Phys. **127** (2007)

[3] M. Vogel *et al.*, J. Chem. Phys. **120** (2004)