Optical response of C$_{60}$ and C$_{70}$ fullerenes:
  Molecular exciton effects in the neutral and maximally doped C$_{60}$ (C$_{70}$) are considered using a tight binding model with long-range Coulomb interactions and bond disorder. By comparing calculated and observed optical spectra, we conclude that relevant Coulomb parameters for the doped cases are about half of those of the neutral systems. The broadening of absorption peaks is well simulated by the bond disorder model. 
Kikuo Harigaya and Shuji Abe (Fundamental Physics Section,   Electrotechnical Laboratory, Japan)