Electron-Hole Excitations in NiO: LSDA + U-Based Calculations vs. Inelastic X-Ray Scattering and Ellipsometry Measurements
- ORNL
- University of Tennessee, Knoxville (UTK)
- University of Illinois, Urbana-Champaign
The performance of the LSDA+U functional - in particular, the quality of the ground-state - is tested via calculations of the electron-hole excitations of NiO, which are compared with (non-resonant) inelastic X-ray scattering (IXS) and ellipsometry measurements. The dynamical density-response calculations are performed within the random-phase approximation (RPA), defining an LSDA+U/RPA density-response method. A significant success of this method is the insight it provides into the main loss present in the IXS data above the NiO optical gap, namely, a peak lying at {approx}7.5 eV. This excitation, which is shown to be collective in nature, and to be induced by e{sub g}-e{sub g} transitions, provides a direct link between the correlated e{sub g}-states and the IXS data. This finding illustrates the power of IXS, combined with correlated-band-structure theory (here, LSDA+U theory), for the investigation of the electronic structure of strongly correlated materials. At the same time, our results indicate that the LSDA+U/RPA response method does not represent a complete theory.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1003372
- Journal Information:
- Journal of Physics and Chemistry of Solids, Vol. 66, Issue 12; ISSN 0022-3697
- Country of Publication:
- United States
- Language:
- English
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