Geometrical and electronic structure of C60 anions

The geometrical and electronic structure of various C60 anions is calculated using a model which couples the bond length to the bond order and to Coulomb interactions between adjacent sites. The total energy of the C60 anions is minimized with respect to variations in the bond length. The geometrical relaxations of the anions, relative to the neutral molecule, are such that the symmetry of the molecule is lowered (Jahn-Teller distortion). In the case of the mono-anion and the di-anion, the geometrical distortions and the charge are localized to one equatorial line around the spherical molecule. We term this type of self-localized defect a cyclon. The distortions of higher anions are best described as resulting from interacting cyclons. These distortions and the corresponding charges are delocalized over practically the whole system. The Jahn-Teller distortions of the C60 anions result in a breaking of the degeneracy of the electronic level and, generally speaking, a broadening of the peaks in the density of states compared to neutral C60. (author). 14 refs, 2 figs