Method for calculating photoionization cross sections of fullerenes in the local density and random phase approximations

A method for calculating the photoionization cross sections of fullerenes taking into account many-electron correlations on the basis of the local density and random phase approximations is proposed and implemented. Calculations are made specifically for fullerenes C 60 and C 20 . It is shown that the photoionization spectrum of C 60 acquires a plasmon resonance whose position and magnitude are in good agreement with experimental results [I.V. Hertel, H. Steger, J. de Vries et al. , Phys. Rev. Lett. 68 , 784 (1992)] and with the results of other calculations [M.J. Puska and R.N. Nieminen, Phys. Rev. A47 , 1181 (1993)]. The emergence of a giant resonance is predicted in the photoionization spectrum of fullerene C 20 with the center at a photon energy on the order of 27 eV, which corresponds to the frequency of resonant surface plasmon oscillations in a conducting sphere.