Empirical correction for PM7 band gaps of transition-metal oxides.

A post-calculation correction is established for PM7 band gaps of transition-metal oxides. The correction is based on the charge on the metal cation of interest, as obtained from MOPAC PM7 calculations. Application of the correction reduces the average error in the PM7 band gap from ~3 eV to ~1 eV. The residual error after correction is shown to be uncorrelated to the Hartree-Fock method upon which PM7 is based. Graphical Abstract Comparison between calculated band gaps and experimental band gaps for binary oxides. The orange crosses are for corrected PM7 band gaps. Blue squares are uncorrected values. The orange crosses fall closer to the diagonal dashed line, showing an overall improvement of the accuracy of calculated values.