The oscillator strengths are represented via the colour shading in the upper panel of 4 (b). At the highly symmetric geometry shown, the first bright state is S 4 at 3.28 eV, with an oscillator strength of 0.45. The lowest ππ * state, S 1 at 3.06 eV, possesses vanishing oscillator strength within the computation. This can be understood by the fact that the analogous state is symmetry forbidden under C i symmetry and assuming that similar orbital interactions are also present at the C 2 geometry. However, once the symmetry is broken, this state is expected to borrow intensity from the bright state suggesting that this state contributes to the lowest energy band in the absorption spectrum, which is found experimentally at 2.65 eV. Next, we move to the second molecule studied here, Cz-AQ. As opposed to Cz-BDT where the lowest state was of local ππ * character, we find in the case of Cz-AQ that the first three states (S 1 , T 1 , T 2 ) are all of nπ * character (orange). The calculated vertical gap between S 1 and T 1 is 0.32 eV which is 0.1 eV smaller than found in Cz-BDT. The T 3 and T 4 states are mixed in character, with mostly local contributions on AQ and smaller amounts of charge transfer from Ph and Cz to the core. The S 2 state is an nπ * state. S 3 and S 4 are both described as charge transfer states with significant Cz→BDT character. Only S 4 has an appreciable oscillator strength, which can, again, be understood in terms of symmetry properties. The S 4 excitation energy is 3.55 eV which is 0.64 eV higher than the experimentally determined absorption maximum, thus ri-ADC(2) overestimates the energy of the bright state by about 0.5 eV for both Cz-BDT and Cz-AQ. Conversely, ri-ADC( ) is expected to underestimate the energies of nπ * states by a few tenths of an eV. Nonetheless, we believe that ri-ADC(2) provides a good reference for the expected state characters involved. In particular, these results indicate that all types of states, i.e., local ππ * /nπ * states and CT states, play a role.