where E s P u is the DFT energy of a plutonium slab with two exposed s-oriented surfaces and A s is the exposed surface area. Surface energies are reported in Table for three antiferromagnetic (AFM) geometries of each surface and compared to previous computations of ferromagnetic (FM) plutonium surfaces. Surface energies of the FM (111) surface with spin polarization have not been previously computed. However, we note that Wu et al. found that spin polarization lowered the computed (100) surface energy by 28%. We can thus apply the same reduction to the non-spin-polarized (111) surface energy from Ray et al., 1342 mJ/m 2 , to approximate the spin-polarized FM (111) surface energy.