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Vector vibrations and the Ioffe-Regel crossover in disordered lattices

S. N. Taraskin·S. R. Elliott
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Abstract

The spectral density for vector vibrations in the f.c.c. lattice with force-constant disorder is analysed within the coherent potential approximation. The phase diagram showing the weak- and strong-scattering regimes is presented and compared with that for electrons. The weak-scattering regime for external long-wavelength vibrational plane waves is shown to be due to sum-rule correlations in the dynamical matrix. A secondary peak below the Brillouin peak for sufficiently large wavevectors is found for the lattice models. The results obtained are supported by precise numerical solutions.

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S. N. Taraskin, S. R. Elliott. 2002-04-25. Vector vibrations and the Ioffe-Regel crossover in disordered lattices. https://doi.org/10.1088/0953-8984%2F14%2F12%2F306

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