  An analysis of the real and imaginary part of the polarization potential in
terms of the relative contributions of the single collective states for the $
^{208}Pb + ^{208}Pb $ system has been done. The polarization potential has been
calculated within the Feshbach formalism taking into account the collective
states calculated with the Wigner function moments method. The contribution of
the isoscalar giant dipole resonance states has been estimated being of the
order of 10 - 20 \% of the total at relatively low incident energy.
