The Energy Spectrum and Optical Absorption Spectrum of Endohedral Fullerenes Lu3N@C80 and Y3N@C80 within the Hubbard Model

The anticommutator Green's functions and energy spectra of fullerene C-80 and endohedral fullerenes Lu3N@C-80 and Y3N@C-80 with symmetry group I-h are obtained analytically within the Hubbard model in the static fluctuation approximation. Their energy states are classified and allowed transitions in the energy spectra of the C-80, Lu3N@C-80 and Y3N@C-80 molecules are determined using group-theory methods. The experimentally observed optical absorption bands of endohedral fullerenes Lu3N@C-80 and Y3N@C-80 are interpreted based on the energy spectra.