Dresden 2009 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 10: Brownian motion and transport I

DY 10.2: Vortrag

Dienstag, 24. März 2009, 14:30–14:45, HÜL 386

Brownian Dynamics with Constraints: An Asymptotic-Expansion Approach — Roman Schmitz and •Burkhard Dünweg — MPI fuer Polymerforschung, Mainz, Germany

We consider the well-known problem of overdamped Brownian motion with holonomic constraints. In the ``rigid'' case, the constraints are viewed as present even on the underlying short ballistic time scales. Conversely, in the ``stiff'' case, the Brownian motion is viewed as the long-time limiting behavior of a system whose constrained degrees of freedom are in reality subject to stiff harmonic forces, and therefore ``fast''. Instead of postulating the limiting equation of motion for this latter case ad hoc, we derive it systematically via a multi-time scale expansion of the Fokker-Planck operator, starting from overdamped dynamics for both ``slow'' and ``fast'' degrees of freedom.