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DY: Fachverband Dynamik und Statistische Physik
DY 9: Statistical Physics 2 - organized by Barbara Drossel (Darmstadt), Sabine Klapp (Berlin) und Thomas Speck (Mainz)
DY 9.3: Vortrag
Montag, 22. März 2021, 11:40–12:00, DYb
On the fluctuation-dissipation theorem of a buckminster fullerene — •Andreas Baer1, David Smith2, and Ana-Sunčana Smith1,2 — 1PULS Group, Institute for Theoretical Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany — 2Division of Physical Chemistry, Ruđer Bošković Institute, Zagreb, Croatia
The fluctuation-dissipation theorem goes back to the first half of the last century with a lot of work in statistical physics sharpening the limits of applicability [1]. The Stokes-Einstein relation is a direct consequence of the fluctuation-dissipation theorem and was recently, within an experimental study, argued to be valid for dissolved buckminster fullerenes [2], while theoretical and simulation studies deny the applicability at such small scales [3]. We perform both equilibrium and constrained molecular dynamics studies of a buckminster fullerene dissolved in toluene. Retrieving velocity and force autocorrelation functions, we can directly show the failure of the fluctuation-dissipation theorem. Additionally, transport coefficients obtained via the Green-Kubo formalism can be compared to the friction coefficient retrieved from the ratio of pulling force and resulting velocity to test the Stokes-Einstein relation. We outline the most important assumptions of the theory not fulfilled and provide a solution to the apparent contradiction with experimental studies.
[1] Zwanzig, R., Annu. Rev. Phys. 1965, 16, 67-102
[2] Pearson, J. et al., J. Phys. Chem. Lett. 2018, 9, 6345-6349
[3] Schmidt J. R. et al., J. Phys. Chem. B 2004, 108, 21, 6767-6771