Photoabsorption of the fullerene C60 and its positive ions

Abstract

The electronic structures and the total photoionization cross sections of the fullerene C60 and its positive ions C60n+ (n=1, 2, 3) are calculated for the photon energy range from the ionization thresholds up to 80 eV and compared with the recent experimental data and other calculations. The theoretical approach is based on the local density approximation, the random phase approximation and the jellium models. In contrast to the previous studies, the Perdew–Wang parametrization for the exchange-correlation energy functional is used at present, which leads to more accurate electronic structures and cross sections. Two jellium models are thoroughly tested: the sphere jellium model and the spherical layer jellium model with a finite thickness. It is shown that the spherical layer jellium model provides more reliable results than the sphere model. Two giant resonances are found in the photoionization spectra of all fullerenes treated. The position and the shape of the resonances are determined in agreement with the experimental data.