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DF: Dielektrische Festkörper

DF 3: Gl
äser I (gemeinsam FV DF/DY)

DF 3.10: Vortrag

Dienstag, 9. März 2004, 12:15–12:30, H23

Relating the macroscopic dynamics of liquid silica to its potential energy landscape — •Aimorn Saksaengwijit and Andreas Heuer — Westfälische Wilhelms–Universität, Institut für Physikalische Chemie, D-48149 Münster

We have studied the dynamics of liquid silica in terms of the potential energy landscape (PEL) defined in configuration space. The concept of superstructures of PEL minima, denoted metabasins, is used to extract the relevant properties of the PEL. On the level of metabasins it turns out that the average residence time ⟨ τ ⟩ is inversely proportional to the diffusion constant, i.e. D(T) = c / ⟨ τ (T) ⟩. The temperature dependence of the residence time can be obtained from the analysis of local escape processes out of individual metabasins. Furthermore we show that the fragile-to-strong transition of silica can be reproduced by using the PEL analysis. This allows us to obtain an improved understanding of the underlying nature of this transition. A comparison to a fragile system (Lennard-Jones liquid) is included.