From Tab. 1, we see that the ROOM3/CISD excitation energies are larger than the TD-DFT excitation energies. However, all three methods predict the same trend when comparing the excitation energies of the first intense transition for different cations: Ama + > Ada + > Ada-CN + . At that, the difference between Ama + and Ada + is very small at the B3LYP level (∼0.02 eV), as also is the difference between Ada + and Ada-CN + at the ROOM3/CISD level.