Relativistic Hartree-Fock-Wigner-Seitz band calculations have been performed for the actinide metals Ac through Bk in order to estimate the Coulomb term U and 5 f electron excitation energies. Our calculations predict that the tetravalent state (four 6 d-7 s conduction electrons) is stable relative to the trivalent state for the lighter elements and that near uranium relative stabilization of the trivalent state occurs. We find that U increases from 2-3 eV for Th to 4-5 eV for the heavier elements considered. 5 f level widths W are estimated and found to decrease from 2 to 1/2 eV; together with the results for U this points to progressive localization of the 5f states. The ratio U/W, which is most indicative of localization, takes on values intermediate between those for 3d and 4f electrons.
Citation: Physical Review B (Condensed Matter and Materials Physics)
Pub Type: Journals