In this study we will use the thoroughly tested tPBE on-top functional for all reported calculations, and the states I whose energies we compute will be the final LASSI eigenstates, |LASSI I ⟩ from Eq. ( ), which is appropriate since we are not concerned in this work with conical intersections or locally avoided crossings along potential energy surfaces. In order to accurately model such phenomena, we would have to compute the PDFT energies of the model states as the diagonal elements of the model-space Hamiltonian matrix in the manner of CMS-PDFT, or replace the molecular Hamiltonian in Eq. ( ) with the derivative of the PDFT energy as in L-PDFT. We leave such developments for future work.