For molecules with unpaired electrons, atomic partial spins can be calculated in a manner analogous to atomic partial charges (for closed-shell molecules without unpaired electrons, the net spin on all atoms is always 0). Atomic partial spins are currently calculated using two methods: Mulliken population analysis and NBO natural atomic populations. We note (Supplementary Information Figures ) that Mulliken atomic partial spins are more wellbehaved than Mulliken atomic partial charges and are qualitatively similar to NBO-based partial spins.