Phonon spectral function for an interacting electron-phonon system

J. E. Han and O. Gunnarsson
Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany

Using exact diagonalzation techniques, we study a model of interacting electrons and phonons. The spectral width of the phonons is found to be reduced as the Coulomb interaction U is increased. For a system with two modes per site, we find a transfer of coupling strength from the upper to the lower mode. This transfer is reduced as U is increased. These results give a qualitative explanation of differences between Raman and photoemission estimates of the electron-phonon coupling constants for A3C60 (A= K, Rb).

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Phys. Rev. B 61 , 8628 (2000).

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