ELECTRONIC ABSORPTION-SPECTRA IN C-60(-) AND C-60(+)

We calculate the electronic absorption spectra of C60- and C60+ within a simple tight-binding model augmented by a Hubbard interaction term. To fit the existing experimental data, the Hubbard U must be of the order of the molecular bandwidth (approximately 10 eV). We predict low-energy electronic absorption peaks (< 0. 7 eV) which should be accessible to experiments. The question of the existence of these relatively low-energy peaks addresses important issues regarding the role of electron-electron correlation in fullerene systems.