Regensburg 2019 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 43: Anomalous diffusion / Brownian motion
DY 43.8: Talk
Thursday, April 4, 2019, 12:00–12:15, H3
Long-time tails of correlation functions of Brownian particles — Suvendu Mandal1, •Lukas Schrack2, Hartmut Löwen1, Matthias Sperl3, and Thomas Franosch2 — 1Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany — 2Institut für Theoretische Physik, Leopold-Franzens-Universität, Technikerstraße 21A, 6020 Innsbruck, Austria — 3Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt, Linder Höhe, 51147 Köln, Germany
The dynamics of Brownian particles of a hard-sphere fluid can be described by generalized Langevin equations. Starting with the microscopic motion of the colloids we use the Zwanzig-Mori projection operator formalism to derive equations of motion for correlation functions. To close the equations, suitable mode-coupling approximations (slowing down of the dynamics due to the caging by neighboring particles) are used. Introducing a logarithmically spaced wavevector grid we investigate the long-wavelength behavior of the system. The velocity autocorrelation function of a tagged particle decays algebraically as ∝ t−5/2 rather than exponentially due to repeated interactions. Comparing the collective dynamics with the self-dynamics for different packing fractions near the glass transition we find that contrary to the self-dynamics the collective dynamics do not slow down.