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DF: Dielektrische Festkörper

DF 5: Gl
äser II (gemeinsam FV DF/DY)

DF 5.3: Vortrag

Dienstag, 25. März 2003, 15:15–15:30, HSZ/403

Understanding the Viscous Slowing Down of Supercooled Liquids in Terms of their Potential Energy Landscape — •Burkhard Doliwa¹ and Andreas Heuer² — ¹Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz — ²Institute of Physical Chemistry, Schlossplatz 4/7, D-48149 Münster

At sufficiently low temperatures, a supercooled liquid resides near the local minima of its high-dimensional potential energy landscape (PEL). Therefore, knowing the statistical properties of PEL minima is sufficient to predict all thermodynamic quantities. Here we demonstrate via computer simulations that macroscopic dynamic quantities like the diffusion coefficient, D(T), can also be inferred from a local PEL analysis. The essential step, however, is to consider whole superstructures of many PEL minima, called metabasins, rather than single minima. Metabasins are reminiscent of protein folding funnels or related structures in the energy landscape of small clusters. We identify a temperature -much above the glass transition- below which D(T) is governed by activated hopping events out of the before-mentioned metabasins. This is in contrast to the current understanding of the glass transition where hopping is deemed to set in at much lower temperatures.