Effect of spin-orbit coupling on the actinide dioxides AnO _2 (An=Th, Pa, U, Np, Pu, and Am): A screened hybrid density functional study

摘要

We present a systematic comparison of the lattice structures, electronic density of states, and band gaps of actinide dioxides, AnO _2 (AnTh, Pa, U, Np, Pu, and Am) predicted by the Heyd-Scuseria-Ernzerhof screened hybrid density functional (HSE) with the self-consistent inclusion of spin-orbit coupling (SOC). The computed HSE lattice constants and band gaps of AnO _2 are in consistently good agreement with the available experimental data across the series, and differ little from earlier HSE results without SOC. ThO _2 is a simple band insulator (f 0), while PaO _2, UO _2, and NpO _2 are predicted to be Mott insulators. The remainders (PuO _2 and AmO _2) show considerable O2pAn5f mixing and are classified as charge-transfer insulators. We also compare our results for UO _2, NpO _2, and PuO _2 with the PBEU, self interaction correction (SIC), and dynamic mean-field theory (DMFT) many-body approximations.