E. Koch(1,2), O. Gunnarsson(1), and R.M. Martin(2)
(1) Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany
(2) Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Il 61801
We study the static screening in a Hubbard-like model using quantum Monte Carlo. We find that the random phase approximation (RPA) is surprisingly accurate almost up to the Mott transition. We argue that the Coulomb pseudopotential mu* is not very much reduced by retardation effects in alkali-doped Fullerenes. Therefore efficient screening is important in reducing mu* sufficiently to allow for an electron-phonon driven superconductivity. In this way the Fullerides differs from conventional picture, where retardation effects play a major role in reducing the electron-electron repulsion.
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Phys. Rev. Lett. 83, 620 (1999).