Localized U 5f electrons in UPd₃ from LDA+U calculations

A generalization of the local-density approximation + U (LDA+U) method which takes into account that in the presence of spin-orbit coupling the occupation matrix of localized electrons becomes nondiagonal in spin indices is used to study the electronic structure of UPd₃ and UPd_1.5Pt_1.5. For both compounds LDA+U calculations give a solution with two localized U 5f electrons. Their energy position agrees well with the binding energy of a U 5f peak observed in photoemission experiments. The calculations also reproduce the shift of the peak position toward the Fermi level upon Pt substitution. The LDA+U results are compared to the results of LDA calculations for ThPd₃ and ThPd_1.5Pt_1.5 and their dependence on the crystal structure is analyzed.