TD-DFT(TDA) absorption spectra are shown in Fig. , each computed using a total of 15 excited states per snapshot, which is not enough to converge the "blue tail" at higher energies. However, λ max is adequately approximated using just three excited states, representing s → p transitions of a particle in a cavity. The fact that ω GDD > ω IE translates into a blueshift in the GDD-tuned spectrum, which is peaked at 2.2 eV as compared to 1.8 eV for the IE-tuned spectrum. (These average excitation energies encompass the lowest three excited states, weighted by oscillator strength.) Similar results are obtained for two other functionals that have been applied to this problem in the past; see Fig. . Interestingly, LRC-ω GDD PBE violates the IE theorem in eq. 3 by an average of 0.3 eV yet predicts vertical IEs that are within 0.1 eV of LRC-ω IE PBE values, which satisfy the IE theorem by construction. This is further evidence of modest sensitivity to ω in the vicinity of the optimally tuned value. In summary, two alternative tuning procedures have been examined for determining an optimal rangeseparation parameter in functionals such as LRC-ωPBE. Both procedures afford accurate excitation energies for transitions that exhibit charge-separated character, a major motivation for the development of LRC functionals and the IE tuning procedure. For small molecules, ω IE ≈ ω GDD , essentially by construction since a single adjustable parameter in the GDD procedure is fit to ω IE data. For large systems, the GDD procedure has a clear advantage in that it is a black-box, one-shot calculation that avoids a laborious scan over ω in order to determine ω IE . For example, in molecules such as O 2 N(Ph) 8 NH 2 and (PPV) 11 , the IE-tuning procedure is about six times more expensive than GDD tuning in our present implementation. Moreover, ω GDD remains wellbehaved in systems where the HOMO/LUMO gap becomes small or behaves erratically. For neutral molecules, GDD tuning avoids the need to perform calculations on an ionized species, which can be an advantage for DFT under periodic boundary conditions.