  The response of fullerenes and carbon nanotubes is investigated by
representing each carbon atom by its atomic polarizability. The polarization of
each carbon atom produces an induced dipole that is the result of the
interaction with a given external field plus the mutual interaction among
carbon atoms. The polarizability is obtained from the dielectric function of
graphite after invoking the Clausius-Mossotti relation. This formalism is
applied to the simulation of electron energy loss spectra both in fullerenes
and in carbon nanotubes. The case of broad electron beams is considered and the
loss probability is analyzed in detail as a function of the electron deflection
angle within a fully quantum-mechanical description of the electrons. A general
good agreement with available experiments is obtained in a wide range of probe
energies between 1 keV and 60 keV.
