Vector vibrations and the Ioffe-Regel crossover in disordered lattices
arXiv:cond-mat/0204549 · doi:10.1088/0953-8984/14/12/306
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.
21 pages, 13 figures