Local density approximation + Hubbard U (LDA + U) band structure calculations reveal that magnetite (Fe3O4) forms an insulating charge-orbital-ordered state below the Verwey transition temperature. The calculated charge ordering is in good agreement with that inferred from recent experiments. We found an associated t(2g) orbital ordering on the octahedral Fe2+ sublattice. Such an orbital orderi...

One of the most topical issues surrounding oxygen vacancies on CeO2(111) is the relative stability of surface and subsurface defects. Using density-functional theory (DFT) with the HSE06 (Heyd-Scuseria-Ernzerhof) hybrid functional as well as the DFT+U approach (where U is a Hubbard-like term describing the on-site Coulomb interactions), we find subsurface vacancies with (2x2) periodicity to be ...

We have performed full-potential linearized augmented plane wave calculations of the Gd~0001! surface using the local density approximation ~LDA! together with the Hubbard U ~LDA1U! total energy functional. The use of LDA1U instead of LDA total energy calculations leads to a ferromagnetic ground state for both bulk Gd and the Gd surface, in agreement with experimental observation. The calculate...

The electronic structures of the metallic and insulating phases of the alloy series Ca2−xSrxRuO4 (0 ≤ x ≤ 2) are calculated using LDA, LDA+U and Dynamical Mean-Field Approximation methods. In the end members the groundstate respectively is an orbitally non-degenerate antiferromagnetic insulator (x = 0) and a good metal (x = 2). For x > 0.5 the observed Curie-Weiss paramagnetic metallic state wh...

Using ab initio electronic structure calculations employing the LDA+U method we have investigated the exchange coupling in materials containing Eu in Eu formal valency including: (i) insulating ferromagnets (EuO, EuS, EuSe, EuTe), and (ii) elemental metal BCC Eu. The total energies calculated with constrained magnetic structures were mapped on the Heisenberg Hamiltonian in order to investigate ...

In recent years understanding of the physics of strongly correlated materials has undergone tremendous increase. This is in part due to the advances in the theoretical treatments of correlations, such as the development of dynamical mean-field theory DMFT .1 This approach offers a minimal description of the electronic structure of correlated materials, treating both the Hubbard and the quasipar...

We propose a fast impurity solver for the general quantum impurity model based on the perturbation theory around the atomic limit, which can be used in combination with the local density approximation LDA and the dynamical mean-field theory DMFT . We benchmark the solver in the two-band Hubbard model within DMFT against quantum Monte Carlo QMC and numerical renormalization-group NRG results. We...