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DY: Fachverband Dynamik und Statistische Physik
DY 7: Statistical Physics (General) I
DY 7.3: Vortrag
Montag, 16. März 2020, 10:30–10:45, ZEU 160
Nonconservative forces and the fluctuation-dissipation theorem — •Kiryl Asheichyk1, 2 and Matthias Krüger3 — 14th Institute for Theoretical Physics, University of Stuttgart, Germany — 2Max Planck Institute for Intelligent Systems, Germany — 3Institute for Theoretical Physics, University of Göttingen, Germany
An equilibrium system which is perturbed by an external potential relaxes to a new equilibrium state, a process obeying the fluctuation-dissipation theorem (FDT). In contrast, perturbing by nonconservative forces yields a nonequilibrium steady state, and FDT can in general not be applied. Here we exploit a freedom inherent to linear response theory: Force fields which perform work that does not couple statistically to the considered observable can be added without changing the response. Using this freedom, we demonstrate that FDT can be applied for certain nonconservative forces. In particular, for the case of shear perturbation, this yields a response formula, alternative to and advantageous over the known Green-Kubo relation.
[1] K. Asheichyk and M. Krüger, arXiv:1908.11287.
[2] K. Asheichyk, A. P. Solon, C. M. Rohwer, and M. Krüger, J. Chem. Phys. 150, 144111 (2019).