deletions | additions       diff --git a/tuning.tex b/tuning.tex  index c6bd45e..3b24d72 100644  --- a/tuning.tex  +++ b/tuning.tex 
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Work by Zanaan, Sawatzsky and Allan showed that the relative alignment of the oxygen 2$p$ and copper 3$d$ orbital levels combined with the magnitude of the onsite repulsion $U$ controls the charge transfer energy. Dynamical mean-field calculations corroborated this picture by showing how the spectral charge transfer energy varies with the underline parameters of the hamiltonian. Additionally, density functional theory showed that the distance of the apical oxygen from the CuO$_2$ plane there is a charge transfer energy. Since we wanted to reduce the charge transfer energy to produce higher Tc's, we replaced the apical oxygen with sulfur, reasoning that its more extended 3$p$ orbitals would screen and reduce the strength of the in plane correlations.  \emph{Structure prediction} -- We chose the $T$-type layered perovskite La$_2$CuO$_4$ as the starting point. Our intuition led us to propose the site substitution of the apical oxygen with sulfur. Due to the larger ionic radius of sulfur as compared to oxygen, we expect that the LaS charge reservoir layer to be crowded. To compensate, we explored the effect of substituting the large La ion with smaller trivalent ions $R$, selected from the lanthanide-like elements. The compositions we considered were $R_2$CuO$_2$S$_2$ (shown in Fig.~\ref{fig:rcuso})  and $R_2$CuO$_3$S. We include the monosulfide in hopes that the configurational entropy of only replacing a quarter of the apical oxygens with sulfur would help stabilize the target phase.