The calculated electronic band structures of the three perovskites are provided in Figs S1-S3, ESI † , and the calculated electronic band gaps E g are compared to previous experimental and theoretical studies in Table . 2. The calculated E g = 4.5 eV for CTO agrees well with the upper range of experimental values reported in Ref. . We were not able to find an experimental bandgap for R3m BTO, but our predicted E g = 4.42 eV is consistent with the values of 4.9 and 5.18 eV obtained in previous theoretical studies. We attribute our smaller predicted value to our use of the screened HSE06 hybrid functional rather than the (unscreened) PBE0 used in Refs and . On the other hand, our predicted E g = 4.15 eV for STO is considerably larger than the 3.4 eV predicted in previous calculations and is also larger than the measured E g = 3.25 eV of cubic STO. Despite these discrepancies, all three perovskites are predicted to be insulators, and we would not expect the overestimation of the bandgap of STO to significantly impact the calculated electrical properties. Calc. 5.18 (indirect) Calc. 4.90