Electron-vibron interactions in charged fullerenes. II. Pair energies and spectra

The ground-state energy shifts and excitation spectra of charged fullerenes C-60(n-), n = 1,...,5 are calculated. The electron-vibron Hamiltonian of part I is extended to include all A(g) and H(g) modes with experimentally determined frequencies and theoretically estimated coupling constants. Complex splitting patterns of H(g) vibrational levels are found. Our results are relevant to EPR measurements of spin splittings in C-60(2-) and C-60(3-) in solution. Spectroscopic gas-phase experiments will be of interest for further testing of this theory. As found in part I, degeneracies in the electron and vibron Hamiltonians give rise to a dynamical Jahn-Teller effect, and to a considerable enhancement of the electronic pairing interaction. This helps to overcome repulsive Coulomb interactions and has important implications for superconductivity in K3C60 and the insulating state in K4C60.