LOW-FREQUENCY RAMAN-SCATTERING IN MODEL DISORDERED SOLIDS - PERCOLATORS ABOVE-THRESHOLD

The Raman coupling coefficients of site-and bond-percolators at concen tration higher than percolation threshold are computed for two scatter ing mechanisms: bond polarizability (BPOL) and dipole-induced-dipole ( DID). The results show that DID does not follow a scaling law at low f requency, while in the case of BPOL the situation is less clear. The n umerically computed frequency dependence in the case of BPOL, which ca n be considered a good scattering mechanism for a wide class of real g lasses, is in semiquantitative agreement with experimental results.