The Energy Spectrum and Optical Absorption Spectrum of Endohedral Fullerenes Lu.sub.3N@C.sub.80 and Y.sub.3N@С.sub.80 within the Hubbard Model

The anticommutator Green's functions and energy spectra of fullerene С.sub.80 and endohedral fullerenes Lu.sub.3N@C.sub.80 and Y.sub.3N@С.sub.80 with symmetry group I.sub.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 С.sub.80, Lu.sub.3N@C.sub.80 and Y.sub.3N@С.sub.80 molecules are determined using group-theory methods. The experimentally observed optical absorption bands of endohedral fullerenes Lu.sub.3N@C.sub.80 and Y.sub.3N@С.sub.80 are interpreted based on the energy spectra.