All-electron Bethe-Salpeter calculations for shallow-core x-ray absorption near-edge structures

Olovsson, Weine; Tanaka, Isao; Mizoguchi, Teruyasu; Puschnig, Peter; Draxl, Claudia

doi:10.1103/physrevb.79.041102

Cited by 73 publications

(73 citation statements)

References 24 publications

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“…The theoretical problems with the leading peaks (B, B2) are likely related to the frozen-core approximation and to dynamical screening effects, i.e., the energy dependence of the complex self-energy [31,32]. The nonlocality of the particle-hole exchange interaction [33] is a further issue. It should be noted that the poor descrip- tion of the leading peaks is a common problem for K-edge XANES of light elements and could so far not be cured by any ab initio method we are aware of, including the Bethe-Salpeter-Equation approach [34].…”

Section: Xanes Of Graphenementioning

confidence: 99%

X-ray absorption spectra of graphene and graphene oxide by full-potential multiple scattering calculations with self-consistent charge density

Krüger

Natoli

et al. 2015

Phys. Rev. B

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X-ray absorption near edge structure (XANES) of graphene, graphene oxide and diamond are studied by the recently developed real-space full potential multiple scattering (FPMS) theory with space-filling cells. It is shown how accurate potentials for FPMS can be generated from self-consistent charge densities obtained with other schemes, especially the projector augmented wave method. Compared to standard multiple scattering calculations in the muffin-tin approximation, FPMS gives much better agreement with experiment. The effects of various structural modifications on the graphene spectra are well reproduced. (1) Stacking of graphene layers increases the peak intensity in the higher energy region. (2) The spectrum of the C atom located at the edge of graphene sheet shows a prominent pre-edge structure. (3) Adsorption of oxygen gives rise to the so-called interlayer-state peak. Moreover, O K-edge spectra of graphene oxide are calculated for three types of bonding, C-OH, C-O-C and C-O, and the proportions of these bondings at 800 • C are deduced by fitting them to the experimental spectrum.

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Section: Xanes Of Graphenementioning

confidence: 99%

X-ray absorption spectra of graphene and graphene oxide by full-potential multiple scattering calculations with self-consistent charge density

Krüger

Natoli

et al. 2015

Phys. Rev. B

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“…With the core-hole potential directly included in the calculation of the electronic states, this method is well suited for extended systems [14][15][16], although requiring supercell calculations to avoid spurious interactions between core holes of neighboring unit cells. For shallower core states, however, the overlap between the initial core state and the conduction bands * vorwerk@physik.hu-berlin.de is usually more relevant and the local treatment of the electron-hole correlation becomes problematic [17]. Indeed, the core-hole approximation is known to fail in case of excitations involving shallow core or even semi-core states, that may interact with the surrounding electrons [18].…”

Section: Introductionmentioning

confidence: 99%

“…3c), is confined within the layer of the absorbing atom. Its extension beyond the size of the unit cell of the material is a signature of the electron-hole correlation, which is typical of bound excitons in the core [17,18,23,56], as well as in the valence region (see, e.g., [8,57]). It is worth noting that the first core exciton in PbI 2 is much more localized than its counterpart in the optical region [55].…”

Section: B Lead M4-edge Spectrum Of Pbi2mentioning

confidence: 99%

Addressing electron-hole correlation in core excitations of solids: An all-electron many-body approach from first principles

2017

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We present an ab initio study of core excitations of solid-state materials focusing on the role of electron-hole correlation. In the framework of an all-electron implementation of many-body perturbation theory into the exciting code, we investigate three different absorption edges of three materials, spanning a broad energy window, with transition energies between a few hundred to thousands of eV. Specifically, we consider excitations from the Ti K edge in rutile and anatase TiO2, from the Pb M4 edge in PbI2, and from the Ca L2,3 edge in CaO. We show that the electronhole attraction rules x-ray absorption for deep core states, when local fields play a minor role. On the other hand, the local-field effects introduced by the exchange interaction between the excited electron and the hole dominate excitation processes from shallower core levels, separated by a spin-orbit splitting of a few eV. Our approach yields absorption spectra in good agreement with available experimental data, and allows for an in-depth analysis of the results, revealing the electronic contributions to the excitations, as well as their spatial distribution.

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“…On the other hand, this method is known to perform worse for excitations from shallow core or semicore states, where e-h correlation becomes relevant [29][30][31][32]. In the core-hole approximation, the exciton binding strength relies on the adopted approximation for the exchange-correlation functional [33]. Moreover, this method requires the construction of a supercell to avoid spurious interactions between neighboring coreholes.…”

Section: B Theoretical Backgroundmentioning

confidence: 99%

Atomic signatures of local environment from core-level spectroscopy inβ−Ga2O3

et al. 2016

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We present a joint theoretical and experimental study on core-level excitations from the oxygen K-edge of β-Ga 2 O 3 . A detailed analysis of the electronic structure reveals the importance of O-Ga hybridization effects in the conduction region. The spectrum from O 1s core electrons is dominated by excitonic effects, which overall red-shift the absorption onset by 0.5 eV, and significantly redistribute the intensity to lower energies. Analysis of the spectra obtained within many-body perturbation theory reveals atomic fingerprints of the inequivalent O atoms. From the comparison of energy-loss near-edge fine-structure (ELNES) spectra computed with respect to different crystal planes, with measurements recorded under the corresponding diffraction conditions, we show how the spectral contributions of specific O atoms can be enhanced while quenching others. These results suggest ELNES, combined with ab initio many-body theory, as a very powerful technique to characterize complex systems, with sensitivity to individual atomic species and to their local environment.

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All-electron Bethe-Salpeter calculations for shallow-core x-ray absorption near-edge structures

Cited by 73 publications

References 24 publications

X-ray absorption spectra of graphene and graphene oxide by full-potential multiple scattering calculations with self-consistent charge density

X-ray absorption spectra of graphene and graphene oxide by full-potential multiple scattering calculations with self-consistent charge density

Addressing electron-hole correlation in core excitations of solids: An all-electron many-body approach from first principles

Atomic signatures of local environment from core-level spectroscopy inβ−Ga2O3

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