Publication: Dynamical structure factor in disordered systems
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Amer Physical Soc
We study the spectral width as a function of the external momentum for the dynamical structure factor of a disordered harmonic solid, considered as a toy model for supercooled liquids and glasses. In the contexts of both the single-link coherent potential approximation and a single-defect approximation, two different regimes are clearly identified: if the density of states at zero energy is zero, the usual p^(4) law is recovered for small momentum. On the contrary, if the disorder induces a nonvanishing density of states at zero energy, a linear behavior is obtained. The dynamical structure factor is numerically calculated in lattices as large as 96^(3) and satisfactorily agrees with the analytical computations.
© 2000 The American Physical Society. We gratefully acknowledge interesting discussions with A. González, M. Mézard, G. Ruocco, and G. Viliani. V.M.M. has been partially supported by CYCyT (Grant Nos. AEN97-1708 and AEN99-1693). Our numerical computations were carried out on the Kalix2 pentium cluster of the University of Cagliari.