Berlin 2012 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 29: Posters II
DY 29.24: Poster
Donnerstag, 29. März 2012, 17:00–19:00, Poster A
Anomalous diffusion analyzed in terms of the distribution of generalized diffusivities — •Tony Albers and Günter Radons — Chemnitz University of Technology, Germany
We investigate two systems that show anomalous diffusion. The first one is the continuous time random walk model with an algebraically decaying waiting time distribution that does not have a finite first moment. This model shows subdiffusive behavior and exhibits so called Weak Ergodicity Breaking. Secondly, we consider the Hamiltonian dynamics of particles under the influence of quenched spatial disorder. Both systems are analyzed by a new tool that we call the distribution of generalized diffusivities pα(D,τ). This distribution is defined as the probability density to find a squared displacement of duration τ divided by the asymptotic time dependence of the mean squared displacement τα. Hence this distribution describes the fluctuations during the diffusion process around the generalized diffusion coefficient that can be obtained from the mean squared displacement and is also equal to the first moment of the distribution pα(D,τ). In this contribution we show for the subdiffusive continuous time random walks how the ensemble-averaged and time-averaged distribution of generalized diffusivities are related to each other and how the anomalous diffusion in phase space can be explained by a modified Levy walk model, which is deduced from the distribution of generalized diffusivities.