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

The ground-state energy shifts and excitation spectra of charged fullerenes C₆₀^n-, n=1,...,5 are calculated. The electron-vibron Hamiltonian of part I is extended to include all Ag and Hg modes with experimentally determined frequencies and theoretically estimated coupling constants. Complex splitting patterns of Hg vibrational levels are found. Our results are relevant to EPR measurements of spin splittings in C₆₀^2- and C₆₀^3- 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 K₃{C}₆₀$ and the insulating state in ${K}₄C₆₀.