Photoabsorption spectra of icosahedral fullerenes:: A semiempirical approach

A semiempirical model has been used to predict the electronic photoabsorption spectra of five icosahedral fullerenes in the range C-60-C-720. The model parameters are first fixed in C-60 by fitting its calculated spectrum to the available experimental data, and then conveniently adjusted to describe the larger fullerenes. The structures observed in the calculated spectra show a tendency to smooth pi and sigma plasmons as the fullerene size increases; however other finite-size features related to the particular geometry of these molecules are still visible at higher resolution. Some consequences of the strong electron screening effects on these spectra are discussed. (C) 2002 American Institute of Physics.