the effective $EPI-FSP$ potential $V_{epi}(q)$ is strongly renormalized by strong correlations, which is a synonym for large repulsion of two electrons on the $Cu$ ions - the doubly occupancy is forbidden. In that case the approximative $q$-dependence of $V_{epi}(q)$ is given by $V_{epi}(q)\approx\lbrack
1+(q/q_{c})^{2}]^{-2}V_{0,epi}(q)$, $q_{c}\sim\delta/a$, where $V_{0,epi}(q)$ is the bare (without strong correlations) coupling constant, $\delta(\ll1)$ is the hole concentration and $a$ is the $Cu-O$ distance [@Kulic-Zeyher1-2]-[@Kulic-PhysRep]. The prefactor is a vertex correction due to strong correlations and it means a new kind of (anti)screening in strongly correlated materials.

![*Left*: The microscopic structure of the $FeSe/SrTiO_{3}$ interface of the $1ML$ $FeSe/SrTiO_{3}$ structure. $h_{0}$ - distance between the $FeSe$ monolayer and $TiO_{2}$ dipolar layer. $\delta h$ is amplitude of the oxygen vibration in the dipolar layer. *Right*: The perpendicular view on the $FeSe-SrTiO_{3}$ interface in the model with one $TiO_{2}$ dipolar layer at the end of the $SrTiO_{3}$ substrate. The anisotropy of the effective dielectric constant $varepsilon$ is shown. The similar schema holds also for the $1ML$ $FeSe/TiO_{2}$ structure[]{data-label="1"}](fig1.eps){width="8cm"}

The interface in $1ML$ $FeSe/SrTiO_{3}$ can be considered as highly anisotropic material with the parallel and perpendicular (to the $FeSe$ plane) dielectric constants $\varepsilon_{\parallel}^{eff}\gg\varepsilon_{\perp
}^{eff}$. It is assumed [@Lee-Interfacial-supplement]-[@Johnston1-2] that the oxygen 