compensate negative effects of $\mu_{ii}^{\ast}$ (on $T_{c}$), i.e. $\lambda_{ii}^{epi}\geq\mu_{ii}^{\ast}$. Since in a narrow band one expects rather large screened Coulomb repulsion $\mu_{ii}^{\ast}$ ($\sim0.2$) then the intra-band $EPI$ coupling should be also appreciable. Moreover, from the experimental side the Raman measurements in Fe-pnictides [@Keimer-A1g] give strong evidence for a large phonon line-width of some $A_{1g}$ modes (where the $As$ vibration along the c-axis dominates). They are almost $10$ times larger than the $LDA$ band structure calculations predict. In [@Kulic-Haghighirad] a model was proposed where high electronic polarizability of $As$ ($\alpha_{As^{3-}}\sim12$ Å$^{3}$) ions screens the Hubbard repulsion and also give rise to a strong $EPI$ with A$_{1g}$ (mainly $As$) modes. An appreciable $As$ isotope effect in $T_{c0}$ was proposed in [@Kulic-Haghighirad], where the stable $^{75}As$ should be replaced by unstable $^{73}As$ - with the life-time of $80$ days, quite enough for performing relevant experiments. The situation is similar with $Fe-Se$ compounds, where an appreciable $EPI$ is expected, since $^{78}Se$ is also highly polarizable ($\alpha_{Se^{2-}}\sim7.5$ Å$^{3}$) and can be replaced by a long-living $^{73}Se$ isotope - the half-time $120$ days. Unfortunately these experiments were never performed.

We end up this digression by paying attention to some known facts, that the $LDA$ band structure 