All calculations are carried out in PySCF. Restricted Hartree-Fock (RHF) and restricted open shell Hartree-Fock (ROHF) reference orbitals are used for closed-shell singlet ground states and doublet ground states respectively. The aug-cc-pVTZ basis is used throughout in line with the basis set choice in the reference work. For the diatomic systems, we create trial orbital sets with λ values ranging from 0 to 2, spaced by 0.25, as was previously successful for main group systems. We then select active spaces by applying APC to each of these trial orbital sets, with two N values, 4 and 8. The second larger N was included to bias towards selecting more virtual orbitals to the active space after initial testing showed trial wave functions with N = 4 missed important character for some excitations to higher energy orbitals. A maximum active space size of (14,14) was used for the APC selections for Cu containing systems (CuH, CuF, CuCl). A maximum (12,12) size was used for all other diatomics. This larger maximum active space size for the Cu containing systems was chosen on the basis of two observations. First, they are treated with a (12,15) active space by Jacquemin et al., which is beyond the allowable active space size with a (12,12) maximum. Second, results for the Cu containing systems with the smaller maximum active space size were much worse than those of the other metals.