We find that in general the AFM configurations have lower surface energies than the corresponding FM surfaces and that the surface energy is minimized by the AFM configuration with planes of magnetization that are parallel to the surface. As a result, we would expect single crystal surfaces of δ-Pu to have AFM geometries that parallel that particular surface. Real structures made from δ-Pu will be polycrystalline with grain boundaries that may prevent such idealized alignment. To give a sense of the relative abundance of each surface orientation in polycrystalline materials, we present Wulff constructions of plutonium nanocrystals for each of the three AFM configurations considered (see Fig. ). For AFM(100) nanoparticles, the lowest energy surface is the (100), accounting for 52% of its surface area. The remainder of the surface is apportioned between (110) surfaces and (111) surfaces. For AFM(111) nanoparticles, surface area is dominated by (111) surfaces (86%)