Berlin 2008 – scientific programme
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DF: Fachverband Dielektrische Festkörper
DF 8: Glasses II (joint session DF/DY)
DF 8.4: Talk
Tuesday, February 26, 2008, 15:15–15:30, EB 407
Properties of the Incoherent Scattering Function as derived from a Continuous Time Random Walk Analysis — •Oliver Rubner and Andreas Heuer — Institut für Physikalische Chemie der Universität Münster
We have shown in previous work that it is possible to describe the dynamics of a binary mixture Lennard-Jones (BMLJ65) model system above the glass transition in terms of a continuous time random walk (CTRW). Here we focus on the connection to experimentally accessible quantities. Approximating the incoherent intermediate scattering function F(q,t) as a stretched exponential function exp(−(t/t0)β) we have been able to derive analytical expressions for the q-dependence of the two parameters t0(q) and β(q). These expressions are well reproduced by simulations of the BMLJ65 system.
We analyse the behaviour of the resulting equations in different q-regimes and are able to interpret their physical content exhibiting close connections to existing work, e.g. on facilitated spin systems. Furthermore system size effects are discussed.