Overall, one observes that the calculated LVC PES, BSE@evGW (panel (a)) as well as TD-DFT) (panel (b)), decently align with the single-point calculations, especially around the equilibrium geometry, where the PES show harmonic characteristics (for a more anharmonic case, see Fig. (a) in ESI †). In particular, we observe a good agreement for the lowest triplet states, which are often difficult to describe properly. Besides the fairly good performance of the LVC approximation as such, the PES of BSE@evGW and TD-DFT show distinct differences. For instance, the lowest excited singlet state potential curve is considerably more displaced (large κ) in TD-DFT as compared with BSE@evGW. This is not surprising given the fact that according to Fig. TD-DFT predicts a dominant MC (anti-bonding)