LOW-ENERGY ELECTRONIC ABSORPTION OF C-60(-)

In light of a recent experiment we reexamine the low-energy optical absorption of C60-. Using a tight-binding model augmented by a Hubbard interaction term we do a single-particle configuration-interaction calculation for C60-. The results of our calculation support the interpretation that the observed first electronic transition is actually the second dipole-allowed transition. It is suggested that for calculations in which the state space is expanded the intensity of the first transition will be greatly suppressed relative to the second transition. Consequently the reason that the first transition is not observed in optical experiments is due to electron-electron correlation. © 1995 The American Physical Society.