Mathematics

Study results from University of Regensburg broaden understanding of physics

  2008 NOV 24 - (VerticalNews.com) -- "A derivation of the fluctuation-dissipation theorem for the microcanonical ensemble is presented using linear response theory. The theorem is stated as a relation between the frequency spectra of the symmetric correlation and response functions," investigators in Regensburg, Germany report.

  "When the system is not in the thermodynamic limit, this result can be viewed as an extension of the fluctuation-dissipation relations to a situation where dynamical fluctuations determine the response. Therefore, the relation presented here between equilibrium fluctuations and response can have a very different physical nature from the usual one in the canonical ensemble. These considerations imply that the fluctuation-dissipation theorem is not restricted to the context of the canonical ensemble, where it is usually derived. Dispersion relations and sum rules are also obtained and discussed in the present case," wrote M.V.S. Bonanca and colleagues, University of Regensburg.

  The researchers concluded: "Although analogous to the Kramers-Kronig relations, they are not related to the frequency spectrum but to the energy dependence of the response function."

  Bonanca and colleagues published their study in Physical Review E (Fluctuation-dissipation theorem for the microcanonical ensemble. Physical Review E, 2008;78(3 Part 1):1107).

  For additional information, contact M.V.S. Bonanca, University of Regensburg, Institute Theoret Physics, D-93040 Regensburg, Germany.

  The publisher of the journal Physical Review E can be contacted at: American Physical Society, One Physics Ellipse, College Pk, MD 20740-3844, USA.

  Keywords: Fluctuation Dissipation Theorem, MathematicsPhysics, University of Regensburg.

  This article was prepared by VerticalNews Mathematics editors from staff and other reports. Copyright 2008, VerticalNews Mathematics via VerticalNews.com.