  The paper continues the rigorous investigations of the mean field Green
function solution of the effective two-dimensional two-band Hubbard model [N.
M. Plakida et al., Phys. Rev. B, Vol.51, 16599 (1995)] of the superconducting
phase transitions in cuprates, started in [Gh. Adam, S. Adam, J. Phys. A: Math.
Theor., Vol.40, 11205 (2007)]. Discussion of the $(\delta, T)$ phase diagram of
the model points to the divergence of the energy spectrum in the limit of
vanishing doping $\delta$. Finite energy spectra at all possible doping rates
$\delta$ are obtained provided the hopping part of the effective Hamiltonian is
renormalized with an effective factor pointing to the site-pairs availability
for fermion hopping processes.
