MODELS OF LOW-WAVE-NUMBER RAMAN-SCATTERING FROM GLASSES

The disorder-induced, low-wavenumber Raman scattering from glasses is ascribed to the fluctuations of the elastooptic tensor (electrical dis order) and of the local strain from its smooth envelope (mechanical di sorder). Phenomenological models of first-order Raman scattering, whic h are able to interpret (at least partially) the salient experimental features, i.e. the Boson peak, the wavenumber dependence of the light- vibration coupling coefficient and the depolarization ratio, are summa rized and compared. The models considered are Martin and Brenig's mode l, the non-continuous glass structure model and the soft potential mod el. Results obtained from numerical simulations on model systems consi sting of simple disordered structures are discussed.