Dresden 2011 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 10: Posters I
DY 10.9: Poster
Monday, March 14, 2011, 17:00–19:00, P4
Rayleigh scattering, long-time tails, and the harmonic spectrum of topologically disordered systems — •Walter Schirmacher1,2, Carl Ganter3, and Stephan Köhler1 — 1Institut für Physik, Univ. Mainz — 2Physik-Department E13, TU München — 3Institut für Radiologie, TU München
We show rigorously [1] that a topologically disordered system interacting harmonically via force constants, which have a sufficiently short-ranged site-distance dependence, exhibits Rayleigh scattering in the low-frequency limit, i.e. a sound attenuation constant, which is proportional to ωd+1, where ω is the frequency and d the dimensionality. This had been questioned in the literature [2]. The corresponding non-analyticity in the spectrum is related to a long-time tail in the velocity autocorrelation function of the analogous diffusion problem, which varies with time t as t−(d+2)/2. A self-consistent theory [1] for the spectrum is formulated, which has the correct analytical properties. [1] W. Schirmacher, C. Ganter, Phys. Rev. B 82, 094205 (2010); [2] T. S. Grigera et al. Nature 422, 289 (2003).