Optical absorption spectrum of metal-nitride compounds of С<sub>80</sub> fullerenes as strongly correlated systems
The energy spectrum of π-electronic subsystem of icosahedral isomer of C<sub>80</sub> fullerene is obtained for the Hubbard model in the static fluctuation approximation. Based on the energy spectrum, the optical absorption spectrum of metal-nitride compounds M<sub>3</sub>N@C<sub>80</sub> (M = Gd, Tm, or Dy) is simulated. The simulated spectrum is in good qualitative agreement with the corresponding experimental spectrum.