Electronic Structure and Elastic Properties of Strongly Correlated Metal Oxides from First Principles: LSDA + U, SIC-LSDA and EELS Study of UO2 and NiO

Abstract

We compare experimentally observed electron energy loss spectra (EELS) of uranium dioxide UO2 and nickel monoxide NiO with the results of ab‐initio calculations carried out by using a method combining the local spin density approximation and the Hubbard U term (the LSDA + U method). We show that by taking better account of strong Coulomb correlations between electrons in the 5f shell of uranium ions in UO2 and in the 3d shell of nickel ions in NiO it is possible to arrive at a better description of electron energy loss spectra, cohesive energies and elastic constants of both oxides compared with local spin density functional theory. For NiO we also compare the LSDA + U results and EELS spectra with a self‐interaction corrected LSDA calculation.

Screened Coulomb interaction calculations: cRPA implementation and applications to dynamical screening and self-consistency in uranium dioxide and cerium

“…DFT+U gives a better description of the band structure of this Mott insulator by opening a gap in agreement with photoemission spectra 5 . As a consequence, the low energy transitions disappear in the polarizability.…”

“…The DFT+U method 1 or the combination of DFT with Dynamical Mean Field Theory method (DFT+DMFT) 2,3 have been successfully applied to a large number of systems in the last twenty years. In particular, these methods have been particularly useful to study the ground state and the photoemission spectra of Mott insulators such as bulk actinide [4][5][6][7][8][9][10][11] and lanthanide oxide [11][12][13][14][15][16] . For instance, to date DFT+DMFT is the only method to give a good description of photoemission spectra of both α and γ cerium [17][18][19][20][21][22] .…”

Lattice thermal conductivity of UO2 using ab-initio and classical molecular dynamics

“…We apply the same value for the effective Hubbard parameter (U ¼ 4.5 eV and J ¼ 0.51 eV) as that used in the literature. [42][43][44][45][46] We have reproduced the previous results (e.g., band structure and electronic density-of-states) [42][43][44][45][46] and verified the suitability of the GGAþ U method.…”

“…The standard DFT calculations fail to simulate the strong correlations among the U 5 f electrons, as reported in several studies. 27,29,[42][43][44][45][46] Here, we use one of the alternatives, i.e., the GGAþ U method, to predict the electronic and phonon behaviors of UO 2 more accurately. We apply the same value for the effective Hubbard parameter (U ¼ 4.5 eV and J ¼ 0.51 eV) as that used in the literature.…”

Band-gap engineering via local environment in complex oxides

“…[3][4][5] However, the poor matching of the band gap E g of most perovskite ABO 3 FE materials (3-4 eV) with the solar spectrum greatly reduces their solar energy conversion efficiency. In the last decades, great efforts have been made to understand electronic band structures [6][7][8][9][10][11][12] and to engineer a lower electronic band gap in oxide materials 13,14 using first-principles calculations. In this work, we use first-principles densityfunctional theory (DFT) calculations to explore how B-site ordering, lattice strain, cation identity, and oxygen octahedral cage tilts affect the electronic band gap in highly tetragonal ferroelectric perovskites.…”