Key Role of Hybridization between Actinide 5<i>f</i> and Oxygen 2<i>p</i> Orbitals for Electronic Structure of Actinide Dioxides

Abstract

In order to promote our understanding on electronic structure of actinide dioxides, we construct a tight-binding model composed of actinide 5 f and oxygen 2 p electrons, which is called f - p model. After the diagonalization of the f - p model, we compare the eigen-energies in the first Brillouin zone with the results of relativistic band-structure calculations. Here we emphasize a key role of f - p hybridization in order to understand the electronic structure of actinide dioxides. In particular, it is found that the position of energy levels of Г 7 and Г 8 states determined from crystalline electric field (CEF) potentials depends on the f - p hybridization. We investiagte the values of the Slater-Koster integrals for f - p hybridization, ( fpσ ) and ( fpπ ), which reproduce simultaneously the local CEF states and the band-structure calculation results. Then, we find that the absolute value of ( fpπ ) should be small in comparison with ( fpσ ) = 1 eV. The small value of |( fpπ )| is consistent with the condition to obtain the octupole ordering in the previous analysis of the f - p model.