Berlin 2012 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 27: Transport and Anomalous Diffusion

DY 27.8: Vortrag

Donnerstag, 29. März 2012, 16:30–16:45, MA 004

Effective diffusion and subdiffusion in inhomogeneous lattice models — •Federico Camboni — Humboldt University Berlin Germany

We discuss the problem of the evaluation of an effective diffusion coefficient for a particle in a disordered medium with energetic disorder (homogeneous and isotropic in the statistical sense) in arbitrary dimension. We present a formal, general expression for such a diffusion coefficient based on the reduction of the system to an effective resistor-capacitor network, with site-dependent activities playing a role of electric potential. We discuss the effective medium approximation for the diffusivity and its upper and lower Hashin-Shtrikman bounds. We moreover investigate situations under which anomalous diffusion in a random potential model can apprear, and show that there are two and only two corresponding situations, namely the ones corresponding to a generalized trap model and to the percolation case.