Energy spectrum and optical absorption spectrum of fullerene С$_{28}$ within the Hubbard model

Anticommutator Green's functions and energy spectra of fullerene С$_{28}$ and endofullerene Zr@C$_{28}$ with the $T_d$ symmetry groups have been obtained in an analytical form within the Hubbard model and static fluctuation approxima-tion. The energy states have been classified using the methods of group theory, and the allowed transitions in the energy spectra of fullerene С$_{28}$ and endofull-erene Zr@C$_{28}$ with the $T_d$ symmetry groups have been determined.