First-principles study of electronic structure and metal–insulator transition of plutonium dihydride and trihydride

The electronic structures of cubic PuH2 and hexagonal PuH3 have been calculated by combining the full potential linearized augmented plane wave method (FLAPW) with the local spin density and generalized gradient approximation plus a Hubbard parameter U (LSDA + U and GGA + U) for considering the strong Coulomb correlation between localized Pu 5f electrons. Our study indicates that PuH2 is metallic, while PuH3 is a semiconductor with a small band gap about 0.26 eV. The bonds in PuH2 system have some covalent character. For PuH3, besides the covalent bonds, particularly, the bonding between Pu and octahedral H atoms is of prominent ionicity. In addition, the conductivity and resistivity data is also worked out at 300 K and low temperature of 4 K. The conductivity decreases from a metallic behavior of PuH2 to the semiconducting region of PuH3. The experimentally undetermined metal–insulator transition has been firstly discovered in Pu–H system theoretically.