Alternatively, Δ𝐸 DSP can be calculated with respect to the CIS states, 53 (d) In the same way as cyclobutadiene is stabilized by DSP in the singlet ground state, molecules with inverted singlet-triplet gaps in the excited state are also stabilized by DSP that can be described by admixture of excited configurations. For singly excited states, this means addition of doubly excited states. Panel b has been adapted from ref. .