The nature of the Pu-5f electronic structure is still under debate. Many of the complications are derived from the necessity of explaining the phase-specific behavior of Pu and Pu alloys, particularly the low-symmetry monoclinic α phase and the high-symmetry fcc δ phase. Experimentally, there are severe impediments, such as the present inability to grow large single crystals and the radioactive and chemical hazards of the materials. Theoretically, no single model has gained universal acceptance because of the limitations of each approach. Recent advances include the application of dynamical mean-field theory (DMFT) to δ-Pu, generalized gradient approximation with a Hubbard U (GGA-U) to δ-Pu~2 and density functional theory with gradient density corrections and spin-orbit polarization to α- and δ-Pu. However, many of the same questions remain from earlier formulations. Several of these key questions revolve around the interaction of the spin and orbital angular momenta. In fact, until now, it was even unclear which momentum-coupling scheme should be used with the Pu-5f states.
展开▼
