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

The ground-state energy shifts and excitation spectra of charged fullerenes C^n-₆₀, 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^2-₆₀ and C^3-₆₀ 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.