  The electron spectrum structure in the half-filled Hubbard model is
considered in terms of the one-particle Green's functions within many-electron
representation. A simple analytical generalization of the single-site
Hubbard-III approximation is obtained, which takes into account the Fermi
excitations (Kondo terms). The problem of the metal-insulator transition is
investigated. The occurrence of a three-peak density-of-states structure
including the "Kondo" peak at the Fermi level is discussed. A comparison with
large-d calculations is performed.
