Strong coupling tbeory of superconducting fullerides near the mott transition

Summary form only given. We describe superconducting Fullerides by a model of weakly coupled molecular levels, in which the bandwidth B and the Debye energy /spl omega//sub D/ have same orders of magnitude. For such a narrow band, electron correlations are supposed to be important. They are discussed in a Hubbard model, using a Gutzwiller approach, which modifies the electron propagators. The gap equation for superconductivity is written in the Eliashberg strong coupling theory. Assuming a simple Frohlich electron-electron attraction, induced by the electron-phonon coupling, the critical temperatum of superconductivity is calculated as a function of B/U, where U is the Hubbard Coulomb energy. Effects of non adiabaticity associated to large Debye energy is discussed by including corrections to Migdal´s theorem. A connection between the critical temperature and the screening effect is made.