Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1482143 | Journal of Non-Crystalline Solids | 2011 | 6 Pages |
An overview is given on the present status of the theoretical description of vibrational spectra of glasses, as seen by inelastic neutron, X-ray and light (Raman) scattering. Using the language of Green's/response functions the merits and shortcomings of a local oscillator and a generalized elasticity-theory point of view are discussed. It is pointed out that in both cases the interaction of phonons with disorder-induced irregularities leads to Rayleigh scattering (mean free path ℓ ∝ ω− 4) at low enough frequencies and temperatures. In disordered solids at ambient temperature the Rayleigh scattering is usually masqued by Akhiezer-like anharmonic scattering ℓ ∝ ω− 2, but it can be made visible by lowering the temperature. Using a combination of fluctuating-elasticity theory with an incoherent spectrum of local oscillators a fair description of the vibrational spectrum of glassy SiO2 can be achieved.