Electronic correlations in uranium hydride UHunder pressure.

We report results of calculations based on density functional theory and dynamical mean-field theory for the electronic structure of uranium hydride UHunder pressure, a compound of the uranium-based hydride family some members of which have been predicted to be superconducting. The effective electronic mass enhancement*/∼ 1.4 indicates that the Coulomb correlations have a moderate strength.

Influence of Molecular Orbitals on Magnetic Properties of [x].

Recent discoveries of various novel iron oxides and hydrides, which become stable at very high pressure and temperature, are extremely important for geoscience. In this paper, we report the results of an investigation on the electronic structure and magnetic properties of the hydride FeO 2 H x , using density functional theory plus dynamical mean-field theory (DFT+DMFT) calculations. An increase in the hydrogen concentration resulted in the destruction of dimeric oxygen pairs and, hence, a specific band structure of FeO 2 with strongly hybridized Fe- t 2 g -O- p z anti-bonding molecular orbitals, which led to a metallic state with the Fe ions at nearly 3+.

Unexpected 3+ valence of iron in FeO, a geologically important material lying "in between" oxides and peroxides.

Recent discovery of the pyrite FeO, which can be an important ingredient of the Earth's lower mantle and which in particular may serve as an extra source of water in the Earth's interior, opens new perspectives for geophysics and geochemistry, but this is also an extremely interesting material from physical point of view. We found that in contrast to naive expectations Fe is nearly 3+ in this material, which strongly affects its magnetic properties and makes it qualitatively different from well known sulfide analogue - FeS. Doping, which is most likely to occur in the Earth's mantle, makes FeO much more magnetic.