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"On anomalous diffusion and response function in one-dimensional models"

Relatore: Dario Villamaina- UniversitÓ di Roma

Aula Feynman
14 Dicembre 2010 ore 15.00

In this talk I will show how the Einstein relation between spontaneous fluctuations and the response to an external perturbation holds in the absence of currents, for the comb model and the elastic single-file, which are examples of systems with subdiffusive transport properties. The relevance of nonequilibrium conditions is investigated: when a stationary current (in the form of a drift or an energy flux) is present, the Einstein relation breaks down. In the case of the comb model, a general relation between response function and an unperturbed suitable correlation function, allows one to explain the observed results. This suggests that a relevant ingredient in breaking the Einstein formula, for stationary regimes, is not the anomalous diffusion but the presence of currents driving the system out of equilibrium.