Resonant Raman scattering in YBa2Cu3O7: Band theory and experiment

Abstract

We have measured and calculated the dependence of the Raman phonon intensities of ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$ on laser frequency. The local-density approximation and the linear muffin-tin-orbital method were used for the calculations. We find good agreement not only in the absolute phonon intensities in zz or xx/yy polarization but also in the shape of the resonance profiles. These results indicate that the local-density approximation gives an essentially correct description of the band structure and of the electron-phonon interaction ±2 eV around the Fermi energy. We interpret our data in terms of specific interband transitions and estimate the mode mixing.