As can be seen, the training set shows a wide variety of excitation energies for the first excited singlet state, covering the whole range of the visible spectrum. Further, both dark as well as bright singlet states can be found in the distribution, with oscillator strengths up to 0.55. Its mean excitation energy and oscillator strengths are found to be Ẽ (𝑆 1 ) = 2.45 eV and fOsc (𝑆 1 ) = 0.16, and 𝐸 (𝑇 1 ) or 2𝐸 (𝑇 1 ) < 𝐸 (𝑆 1 ), respectively.