On the other hand, the previous DVS-tPBE results reported for organic systems are in good agreement with the results using hand-selected active spaces of Sarkar et al. So, the larger difference in performance between DVS and hand-selected active spaces here may be due to the fact that MC-PDFT approaches perform much more poorly than NEVPT2 on the transition metal dimers, thus making tPBE a poorer guide for selecting between different active spaces. Regardless, we note that removing bias from active space selection has been a long-standing goal of automated active space approaches and one should expect some degree of deterioration in the performance of these methods from removing this bias.