Leonid Pourovskii

Bandwidth and Fermi surface of iron oxypnictides: Covalency and sensitivity to structural changes

Some important aspects of the electronic structure of the iron oxypnictides depend very sensitively on small changes in interatomic distances and bond angles within the iron-pnictogen subunit. Using first-principles full-potential electronic structure calculations, we investigate this sensitive dependence, contrasting in particular LaFeAsO and LaFePO. The width of the Fe bands is significantly larger for LaFePO, indicating a better metal and weaker electronic correlations. When calculated at their experimental crystal structures, these two materials have significantly different low-energy band structures. The topology of the Fermi surface changes when going from LaFePO to LaFeAsO, with a three-dimensional hole pocket present in the former case transforming into a tube with two-dimensional dispersion. We show that the low-energy band structure of LaFeAsO evolves toward that of LaFePO as the As atom is lowered closer to the Fe plane with respect to its experimental position. The physical origin of this sensitivity to the iron-pnictogen distance is the covalency of the iron-pnictogen bond, leading to strong hybridization effects. To illustrate this, we construct Wannier functions, which are found to have a large spatial extension when the energy window is restricted to the bands with dominant iron character. Finally, we show that the Fe bandwidth slightly increases as one moves along the rare-earth series in REFeAsO and we discuss the physical origin of this effect.

Dynamical mean-field theory within an augmented plane-wave framework: Assessing electronic correlations in the iron pnictide LaFeAsO

We present an approach that combines the local-density approximation (LDA) and the dynamical mean-field theory (DMFT) in the framework of the full-potential linear augmented plane-wave method. Wannier-type functions for the correlated shell are constructed by projecting local orbitals onto a set of Bloch eigenstates located within a certain energy window. The screened Coulomb interaction and Hunds coupling are calculated from a first-principles constrained random-phase approximation scheme. We apply this

The most incompressible metal osmium at static pressures above 750 gigapascals

\text{LDA}+\text{DMFT}

Self-consistency over the charge density in dynamical mean-field theory: A linear muffin-tin implementation and some physical implications

implementation, in conjunction with a continuous-time quantum Monte Carlo algorithm, to the study of electronic correlations in LaFeAsO. Our findings support the physical picture of a metal with intermediate correlations. The average value of the mass renormalization of the

Importance of electronic correlations for structural and magnetic properties of the iron pnictide superconductor LaFeAsO

\text{Fe}\text{ }3d

Local moment vs. Kondo behavior of the 4f-electrons in rare-earth iron oxypnictides

bands is about 1.6, in reasonable agreement with the picture inferred from photoemission experiments. The discrepancies between different

Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition

\text{LDA}+\text{DMFT}

Impact of electronic correlations on the equation of state and transport in epsilon-Fe

calculations (all technically correct) which have been reported in the literature are shown to have two causes: (i) the specific value of the interaction parameters used in these calculations and (ii) the degree of localization of the Wannier orbitals chosen to represent the

Theoretical prediction and spectroscopic fingerprints of an orbital transition in CeCu2Si2.

\text{Fe}\text{ }3d

Rare-earth vs. heavy metal pigments and their colors from first principles

states, to which many-body terms are applied. The latter is a fundamental issue in the application of many-body calculations, such as DMFT, in a realistic setting. We provide strong evidence that the DMFT approximation is more accurate and more straightforward to implement when well-localized orbitals are constructed from a large energy window encompassing