Screening, Coulomb pseudopotential, and superconductivity in alkali-doped Fullerenes

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.

A postscript file is available at this http URL

Phys. Rev. Lett. 83, 620 (1999).

Max-Planck Institut für Festkörperforschung
Postfach 800 665 D-70506 Stuttgart