A linear decrease in the computed VEEs with increasing N emb is observed. Consequently, it is possible to extrapolate the VEEs to the non-embedding limit, the values of which are reported in Table . Let us now discuss the photoionization. We aim to understand how a 'local' embedding framework handles an electronic transition involving a 'delocalized' state. The CAS-DMET and NEVPT2-DMET VEEs for this excitation from A 1g to CBM are plotted in Figure . Next, we examine the singlet-triplet transition of the F 0 center. Experimentally, there are two peaks in the emission spectra at 2.3 eV and 3.2 eV, attributed to the F 0 and F + centers, respectively. Since the lifetime of the F 0 photoluminescence is longer, it has been suggested that the emission occurs through a triplet to singlet transition. Therefore, we first show in Figure the VEEs from the singlet a 1g ground state to the triplet t 1u state, following the same procedure of varying embedding space described above for singletsinglet transitions. The difference between CAS-DMET and NEVPT2-DMET values is less compared to the analogous singlet-singlet transition. This implies a lower degree of dynamic correlation for the triplet excited states.