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DY: Fachverband Dynamik und Statistische Physik

DY 23: Stochastic Thermodynamics

DY 23.7: Talk

Wednesday, March 20, 2024, 11:00–11:15, BH-N 128

Nonequilibrium fluctuations of chemical reaction networks at criticality — •Benedikt Remlein and Udo Seifert — II. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart, Germany

Chemical reaction networks can undergo nonequilibrium phase transitions upon variation of external control parameters like the chemical potential of one species. We investigate the critical fluctuations of the flux in the associated chemostats, which is proportional to the entropy production, for two paradigmatic models, the Schlögl model and the Brusselator. In both cases, numerical simulations show that the corresponding diffusion coefficient diverges at the critical point as a function of system size albeit with different exponents. In the vicinity of the transition, the diffusion coefficient in the Schlögl model follows a scaling form. We develop an analytical approach based on van Kampen's system size expansion that yields these exponents. For the Brusselator model, we numerically find that the diffusion coefficient as function of the control parameter develops a discontinuity while increasing the system size.

Keywords: chemical reaction networks; nonlinear dynamics; critical fluctuations; bifurcations