Multiband electron-phonon coupling in the cuprates: Raman scattering and charge fluctuations

The role of multiband electron-phonon coupling for phonon Raman scattering and phonon-induced charge fluctuations in the high-T-c cuprates is consider ed. Comparison of contributions from different bands to the phonon Roman ve rtex shows that the scattering intensity comes mainly from hole-phonon rath er than from electron-phonon coupling and is very sensitive to doping. Inte rband electron-phonon coupling is as important for the phonon-induced charg e fluctuations as electron-phonon coupling near the Fermi surface. The role of the latter increases near the Van Hove singularity in the electronic sp ectrum.