Magnetic state of δ- and α-plutonium

Total energies of non-magnetic, ferromagnetic and antiferromagnetic phases of Pu in the fcc structure (δ phase) have been calculated by the full-potential linear augmented-plane-wave method. The antiferromagnetic solution (of the CuAu type) has been found as the most stable one. The ground-state equilibrium volume per atom agrees well with that of the low-temperature monoclinic α phase. The latter includes 8 pairs of atoms per unit cell and resembles a frustrated body-centered tetragonal structure, making it logical to assume the antiferromagnetic ordering related to the CuAu-type in the fcc structure for the α phase as well. Such magnetic solution has indeed been found, with magnetic moments not much different from those in the fcc phase.