ELECTRONIC-STRUCTURE OF PURE AND K-DOPED C60 CLUSTERS

The electronic structure of a C60 cluster, the soccer ball-shaped structure determined from the recent X-ray study by Hawkins et al., and of its endohedral complex KC60 were calculated using the self-consistent-field discrete variational (DV) method in the local density theoretical framework. The calculated C60 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 KC60 cluster is the same as the C60 except that K donates one electron into the lowest unoccupied molecular orbital of C60. The electronic charge density of C60 was found to lie within a spherical shell of almost-equal-to 8.0 au thickness surrounding the C nuclei. A cage of almost-equal-to 2.0 au radius at the center of the C60 cluster was found nearly free of electrons (rho << 10(-3) e/a0(3)). The 29 eV plasma energy loss calculated approximately from the dielectric function of C60 explains the broad satellite feature seen almost-equal-to 28 eV to the higher energy side from the C 1s core line in the XPS experiment.