Chemical substitution, combined with strain, allows the charge-transfer
energy in hole-doped cuprates to be broadly tuned. We theoretically
characterize the structural and electronic properties of the family of
compounds R2CuO2S2, constructed by sulfur replacement of the apical
oxygens and rare earth substitutions in the parent cuprate La2CuO4.
Additionally, the enthalpies of formation for possible synthesis pathways are
determined.Comment: 5 pages, 5 figure