Electronic States of C60 Ions vs Electron Interaction and Energetics of A3C60 Fullerides

Abstract

The charge dependencies of energies E(Q of free correlated C60 cations and anions are calculated accounting for the full configuration interaction (CI) within the corresponding active spaces and the icosahedral C60 symmetry. For Hubbard and Coulomb-like electron-electron (e-e) potentials, opposite Q-sequences of ground-state anion energies E(Q) are found, predicted energies are consistent with experimental data only when the Coulomb long-range interactions are involved. Basing on the calculated E(Q) and the Madelung energy evaluation, the energetics of A3C60, crystals (A=Li, Na, K, Rb) in different charge states is considered with varied screenings of e-e potentials inside and outside fullerene cages. The screening areas are specified, in which a partial metal-fullerene electron transfer is more preferable than complete.