Results for the (16,15) active space are presented in Table and Fig. . LASSIS agrees with the previously reported LASSI[1,5 CT ] results, and is very close to the DMRG reference in all cases. However, the CASPT2 (16,15) results of reference 44 suggest that ignoring dynamical correlation results in an underestimation of the energy gaps between low-and high-spin states. Our DMRG-PDFT and LASSIS-PDFT results confirm this, and the agreement between DMRG-PDFT and LASSIS-PDFT is close, similar to the agreement between LASSI and DMRG.