Collective electronic excitations inC60clusters

The large number of active electrons in a ${\mathrm{C}}_{60}$ cluster and the strong Coulomb interaction among them leads to a rich spectrum of collective states. States with total angular momentum up to L=8ħ have a strong collective character. The equivalent of both π and σ plasmons in graphite are predicted. In the low-energy region a strong dynamical screening is obtained, in good agreement with measured absorption spectra. The theoretical results compare very well with photoexcitation and electron-energy-loss-spectroscopy data on gas targets in the high-energy domain.