ELECTRONIC STATES AND STRUCTURE OF D2 C-76

We have examined by high-level calculations the electronic structure of the recently isolated chiral fullerene molecule C76 (R. Ettl, I. Chao, F, Diederich and R.L. Whetten, Nature 353 (1991) 149. The relaxed structure maintains D2 symmetry and has near-ideal bonding angles and lengths for fullerene structures. The electronic density-of-states is dominated by p-pi orbitals near the Fermi energy, where it closely resembles the naive tight-binding (Huckel) pattern. The calculated low-energy optical spectrum, and the small HOMO-LUMO gap (1.1 eV) in particular, are in agreement with experiment, and allow for a detailed interpretation of observed near-infrared spectral bands, in terms of four allowed transitions. The vertical ionization potential (8.1 eV) and electron affinity (2.9 eV) are also predicted.