Optical absorption spectra of A6C60: Reduction of effective   Coulombinteractions
  Optical absorption spectra of C60^6- are theoretically investigated in order to analyze the optical properties of alkali metal doped fullerites A6C60. We use a tight binding model with long ranged Coulomb interactions and bond disorder. Optical spectra are obtained by the Hartree-Fock approximation and the CI method. The Coulomb interaction parameters which are relevant to the optical spectra of A6C60 are almost the half of those of the neutral C60. The reduction of the effective Coulomb interactions is concluded for the heavily doped case of C60. 
Kikuo Harigaya (ETL - Japan)