Dresden 2006 – wissenschaftliches Programm

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AKB: Biologische Physik

AKB 30: Poster Session I

AKB 30.21: Poster

Montag, 27. März 2006, 15:30–18:00, P1

Thermodynamics along a stochastic trajectory for chemical reaction networks — •Tim Schmiedl and Udo Seifert — II. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57/III, 70550 Stuttgart

We model chemical reaction networks by a master-equation approach. Defining the thermodynamic state variables energy and entropy along a stochastic trajectory, we develop a consistent theory of thermodynamics including the first and second law. Entropy fluctuations are constraint by a fluctuation theorem, which can be regarded as an extension of the second law of thermodynamics. This fluctuation theorem is valid for systems driven arbitrarily far out of equilibrium. The reaction system can be maintained in a nonequilibrium steady state (NESS) where detailed balance is violated. Furthermore, transitions between equilibrium steady states due to time dependent rates generate nonequilibrium distributions if they are not driven infinitesimal slowly (adiabaticly). We examplify these results for a three-species cyclic reaction network with time dependent rates and discuss NESS as well as rate-driven transitions between steady states. For large systems, a usual approach to solve master equations approximatively is the system-size expansion by van Kampen. We discuss how the fluctuation theorem transfers to this mesoscopic description for two paradigmatic reaction networks.