  We calculated multiplet splittings for positively and negatively charged
fullerene ions within the CAS SCF method, and extracted model parameters for
the intramolecular Hamiltonian. The method treats correctly the symmetry of
ground and excited states for partially occupied degenerate molecular orbitals.
We compare our results to previous calculations by the LDA, MNDO and model SCF
methods. The multiplet averaged Coulomb parameter U is about 3.1 eV for
electrons and 3.2 eV for holes. The Hund's rule exchange parameter J is found
to be 113 meV for electrons and 192 meV for holes.
