title: Numerical test of hydrodynamic fluctuation theory in the Fermi-Pasta-Ulam chain.
abstract: Recent work has developed a nonlinear hydrodynamic fluctuation theory for a chain of coupled anharmonic oscillators governing the conserved fields, namely, stretch, momentum, and energy. The linear theory yields two propagating sound modes and one diffusing heat mode, all three with diffusive broadening. In contrast, the nonlinear theory predicts that, at long times, the sound mode correlations satisfy Kardar-Parisi-Zhang scaling, while the heat mode correlations have Lévy-walk scaling. In the present contribution we report on molecular dynamics simulations of Fermi-Pasta-Ulam chains to compute various spatiotemporal correlation functions and compare them with the predictions of the theory. We obtain very good agreement in many cases, but also some deviations.
authors.affiliation: Raman Research Institute, CV Raman Avenue, Sadashivanagar, Bangalore 560080, India.
authors.forename: Suman G
authors.initials: SG
authors.lastname: Das
authors.affiliation: International Center for Theoretical Sciences, TIFR, IISC Campus, Bangalore 560012, India.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Dhar
authors.affiliation: Department of Physics, Keio University, Yokohama 223-8522, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Saito
authors.affiliation: Zentrum Mathematik, TU München, Boltzmannstraße 3, 85747 Garching, Germany.
authors.forename: Christian B
authors.initials: CB
authors.lastname: Mendl
authors.affiliation: Institute for Advanced Study, Einstein Drive, Princeton, New Jersey 08540, USA.
authors.forename: Herbert
authors.initials: H
authors.lastname: Spohn
mesh_terms: D006358:Hot Temperature; D057446:Hydrodynamics; D056004:Molecular Dynamics Simulation