Electronic structure of pure and K-doped C 60 clusters

Abstract

The electronic structure of a C 60 cluster, the soccer ball-shaped structure determined from the recent X-ray study by Hawkins et al., and of its endohedral complex KC 60 were calculated using the self-consistent-field discrete variational (DV) method in the local density theoretical framework. The calculated C 60 cluster energy levels were found in excellent agreement with the recent X-ray photoemission spectra (XPS) of Weaver et al. The ionization potential and electron affinity calculated using the transition state method are in good agreement with the experimental data. It was found that electronic structure of the endohedral complex KC 60 cluster is the same as the C 60 except that K donates one electron into the lowest unoccupied molecular orbital of C 60. The electronic charge density of C 60 was found to lie within a spherical shell of ≈8.0 au thickness surrounding the C nuclei. A cage of ≈2.0 au radius at the center of the C 60 cluster was found nearly free of electrons ( p⪡ 10 −3 e/ a 3 0). The 29 eV plasma energy loss calculated approximately from the dielectric function of C 60 explains the broad satellite feature seen ≈28 eV to the higher energy side from the C 1s core line in the XPS experiment.