1ST-PRINCIPLE STUDY OF HYBRIDIZATION EFFECTS AND MAGNETIC-ORDERING IN CORRELATED-ELECTRON URANIUM SYSTEMS

Correlated-f-electron systems have a wide range of f-electron delocalization varying from ''almost localized'' to ''almost itinerant.'' Previously, techniques to calculate hybridization and exchange Coulomb interaction in the f-electron systems have been developed from the ''core point of view.'' Such a procedure is appropriate for ''almost localized'' systems, i.e., typically cerium systems where the electrons of interest are 4f. Here techniques for the same purposes are discussed, and that to calculate hybridization is developed in detail, from a ''band point of view'' in order to treat ''almost itinerant'' systems, i.e., typically light actinide systems where the electrons of interest are 5f such as uranium systems. Calcualtions have been done for uranium monopnictides and monochalcogenides. Results on magnetic ordering are in good agreement with experiment. Validity and limitations of the two points of view are discussed in regard to their application to realistic systems.