In any case, the transformation to Boys orbitals once again destroys the utility of the metric, as Γ Boys cannot separate the Rydberg and CT transitions from the localized excitations. Guido et al. suggest using Γ NTO rather than Γ CMO as the metric, due to instabilities in (∆r) CMO for Rydberg excitations, and Fig. plots errors in TD-B3LYP excitation energies as a function of both quantities. (They are plotted separately in Fig. . See Tables and for the data set.) Both representations manage to separated localized excitations from the others, yet the fact that the numerical value of Γ is sensitive to the choice of MOs is problematic if one wants to interpret its value as a quantitative measure of charge displacement, or a "trust radius" for TD-DFT. The absolute difference |Γ CMO -Γ NTO | averages 0.60 ± 0.76 Å but there are significant outliers, and Γ CMO -Γ NTO does not have a consistent sign. For the localized excitations, the largest difference is |Γ CMO -Γ NTO | = 1.4 Å (for the tripeptide) while for the Rydberg and CT states the largest differences are 3.25 Å (for a Rydberg state of H 2 CO) and and 2.6 Å (for a ππ * state of the tripeptide), respectively.