Microscopic analysis of multipole susceptibility of actinide dioxides: A scenario of multipole ordering in AmO$_2$

Key role of hybridization between actinide 5f and oxygen 2p orbitals for electronic structure of actinide dioxides

In order to promote our understanding on electronic structure of actinide dioxides, we construct a tight-binding model composed of actinide $5f$ and oxygen $2p$ electrons, which is called $f$-$p$ model. After the diagonalization of the $f$-$p$ model, we compare the eigenenergies 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 $Γ_7$ and $Γ_8$ states determined from cr…

通过芯能级光电子能谱探测锕系和镧系二氧化物中$f$态的局域化与杂化

Localization versus hybridization of $f$ states in actinide and lanthanide dioxides probed in core-level photoemission spectra

本研究通过多种理论方法计算锕系与镧系二氧化物的芯能级XPS谱，揭示了两类材料f态局域化与杂化特性的差异及成因。

Electronic structure and ionicity of actinide oxides from first principles calculations

The ground state electronic structures of the actinide oxides AO, A2O3 and AO2 (A=U, Np, Pu, Am, Cm, Bk, Cf) are determined from first-principles calculations, using the self-interaction corrected local spin-density (SIC-LSD) approximation. Emphasis is put on the degree of f-electron localization, which for AO2 and A2O3 is found to follow the stoichiometry, namely corresponding to A(4+) ions in the dioxide and A(3+) ions in the sesquioxides. In contrast, the A(2+) ionic configuration is not favorable in the monoxides, which therefore become metallic. The energetics of the oxidation and reducti…

Electronic structure and core-level spectra of light actinide dioxides in the dynamical mean-field theory

The local-density approximation combined with the dynamical mean-field theory (LDA+DMFT) is applied to the paramagnetic phase of light actinide dioxides: UO2, NpO2, and PuO2. The calculated band gaps and the valence-band electronic structure are in a very good agreement with the optical absorption experiments as well as with the photoemission spectra. The hybridization of the actinide 5f shell with the 2p states of oxygen is found to be relatively large, it increases the filling of the 5f orbitals from the nominal ionic configurations with two, three, and four electrons to nearly half-integer …

Self-consistent density functional calculations of the crystal field levels in lanthanide and actinide dioxides

Using a recently developed method combining a nonspherical self-interaction corrected LDA+$U$ scheme and an on-site multi-body Hamiltonian [Phys.\ Rev.\ B 83, 085106 (2011)], we calculate the crystal field parameters and crystal field (CF) excitation levels of $f$-element dioxides in the fluorite structure with $f^{n}$ electronic configurations, including $n=1$ (PaO$_{2}$, PrO$_{2}$), $n=2$ (UO$_{2}$), $n=3$ (NpO$_{2}$), and $n=4$ (PuO$_{2}$). It is shown that good agreement with experimental data (within approximately 10 to 20 meV) can be obtained in all cases. The properties of the multi-ele…

Microscopic theory of the insulating electronic ground states of actinide dioxides AnO2 (An=U, Np, Pu, Am, and Cm)

The electronic ground states of the actinide dioxides AnO2 (with An=U, Np, Pu, Am, and Cm) are investigated employing first-principles calculations within the framework of the local density approximation +U (LDA+U) approach, implemented in a full-potential linearized augmented plane-wave scheme. A systematic analysis of the An-5f states is performed which provides intuitive connections between the electronic structures and the local crystalline fields of the f states in the AnO2 series. Particularly the mechanisms leading to the experimentally observed insulating ground states are investigated…