An analytical model for screened Coulomb interaction in C60 cluster

An analytical model for the static screened Coulomb interaction of a semiconductor sphere that accurately reproduces the screening properties of an icosahedral C60 cluster is presented. Compared with the static screened Coulomb interaction determined after polarizability calculations it yields the same value for nearest-neighbor interaction energy and the same antiscreening effect for distant sites for points located on the nuclear grid of a free molecule. Also the static dipole molecular polarizability turns out to be in good agreement with that calculated after different theoretical methods. When extended to finite frequencies, without introducing other parameters, the present model reproduces the main resonance around 20 eV of the optical absorption spectrum for the gas phase C60 and the giant plasmon resonance around 28 eV observed in C60 fullerites via electron energy loss spectroscopy. These results turn out to be largely insensitive to the details of the model.