X‐Ray Spectroscopy Calculations within Kohn–Sham DFT: Theory and Applications

Leetmaa, Mikael; Ljungberg, Mathias P.; Nilsson, Anders; Pettersson, Lars G. M.

doi:10.1002/9783527625482.ch12

Cited by 5 publications

(4 citation statements)

References 128 publications

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“…14 Other important methods are Wannier-Type Atomic Orbitals (WTAO), 10 the d-band model by Hammer and Nørskov,15 reactivity indices 16 and concepts, 17 or computation of spectroscopic properties. 18 Furthermore, natural bond orbital (NBO) analysis was recently extended to periodic systems by Dunnington and Schmidt 19 and Galeev et al 20 Bond order methods date back to Pauling 21 and the "mobile order" defined by Coulson. 22 These methods were subsequently reformulated many times.…”

Section: Introductionmentioning

confidence: 99%

A periodic energy decomposition analysis method for the investigation of chemical bonding in extended systems

Raupach

Tonner

2015

The Journal of Chemical Physics

110

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The development and first applications of a new periodic energy decomposition analysis (pEDA) scheme for extended systems based on the Kohn-Sham approach to density functional theory are described. The pEDA decomposes the bonding energy between two fragments (e.g., the adsorption energy of a molecule on a surface) into several well-defined terms: preparation, electrostatic, Pauli repulsion, and orbital relaxation energies. This is complemented by consideration of dispersion interactions via a pairwise scheme. One major extension toward a previous implementation [Philipsen and Baerends, J. Phys. Chem. B 110, 12470 (2006)] lies in the separate discussion of electrostatic and Pauli and the addition of a dispersion term. The pEDA presented here for an implementation based on atomic orbitals can handle restricted and unrestricted fragments for 0D to 3D systems considering periodic boundary conditions with and without the determination of fragment occupations. For the latter case, reciprocal space sampling is enabled. The new method gives comparable results to established schemes for molecular systems and shows good convergence with respect to the basis set (TZ2P), the integration accuracy, and k-space sampling. Four typical bonding scenarios for surface-adsorbate complexes were chosen to highlight the performance of the method representing insulating (CO on MgO(001)), metallic (H2 on M(001), M = Pd, Cu), and semiconducting (CO and C2H2 on Si(001)) substrates. These examples cover diverse substrates as well as bonding scenarios ranging from weakly interacting to covalent (shared electron and donor acceptor) bonding. The results presented lend confidence that the pEDA will be a powerful tool for the analysis of surface-adsorbate bonding in the future, enabling the transfer of concepts like ionic and covalent bonding, donor-acceptor interaction, steric repulsion, and others to extended systems.

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Section: Introductionmentioning

confidence: 99%

A periodic energy decomposition analysis method for the investigation of chemical bonding in extended systems

Raupach

Tonner

2015

The Journal of Chemical Physics

110

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“…In StoBe-deMon the ramping function-width convolution method is an established part of the code, in which the width of the peak-shape function varies linearly between minimum and maximum values at arbitrarily chosen energies. As previously discussed, , with XAS this pragmatic method compensates for discrete sampling of the continuum by smearing out unrealistic sharp features, yielding simulated spectra which resemble experiment. Both Orca and StoBe-deMon outputs were convoluted using a pseudo-Voigt peak-shape function using the ramping function-width convolution method, with the XAS additionally including an integrated pseudo-Voigt step function (an erf function plus an arctangent) to simulate the edge step.…”

Section: Methodsmentioning

confidence: 98%

Sulfur X-ray Absorption and Emission Spectroscopy of Organic Sulfones

et al. 2023

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The sulfones are a widespread group of organo-sulfur compounds, which contain the sulfonyl SO 2 group attached to two carbons and have a formal sulfur oxidation state of +2. We have examined the sulfur K near-edge X-ray absorption spectroscopy (XAS) of a range of different sulfones and find substantial spectroscopic variability depending upon the nature of the coordination to the sulfonyl group. We have also examined the sulfur Kβ X-ray emission spectroscopy (XES) of selected representative sulfones. Density functional theory simulations show satisfactory reproduction of both absorption and emission spectra while enabling assignment of the various transitions comprising the spectra. The correspondence between observed and simulated spectra shows promise for ab initio prediction of sulfur X-ray absorption and emission spectra of sulfones of any substituent. The absorption spectra and, to a lesser extent, the emission spectra are sensitive to the nature of the organic groups bound to the sulfonyl (SO 2 ) moiety, clearly showing the potential of X-ray spectroscopy as an in situ probe of sulfone chemistry.

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“…Typical values used were 2.1 eV full-width half-maximum (fwhm) at 12290 to 12.0 eV at 12350 eV. As previously discussed, , this pragmatic method attempts to compensate for discrete sampling of the continuum by smearing out unrealistic sharp features and yields simulated spectra that resemble the experiment. Spectra were computed using the sum of the electric dipole, the magnetic dipole, and the electric quadrupole transition intensities.…”

Section: Experimental Methodsmentioning

confidence: 99%

Mercury Lα1 High Energy Resolution Fluorescence Detected X-ray Absorption Spectroscopy: A Versatile Speciation Probe for Mercury

et al. 2022

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Mercury is in some sense an enigmatic element. The element and some of its compounds are a natural part of the biogeochemical cycle; while many of these can be deadly poisons at higher levels, environmental levels in the absence of anthropogenic contributions would generally be below the threshold for concern. However, mercury pollution, particularly from burning fossil fuels such as coal, is providing dramatic and increasing emissions into the environment. Because of this, the environmental chemistry and toxicology of mercury are of growing importance, with the fate of mercury being vitally dependent upon its speciation. X-ray absorption spectroscopy (XAS) provides a powerful tool for in situ chemical speciation, but is severely limited by poor spectroscopic energy resolution. Here, we provide a systematic examination of mercury Lα1 high energy resolution fluorescence detected XAS (HERFD–XAS) as an approach for chemical speciation of mercury, in quantitative comparison with conventional Hg LIII-edge XAS. We show that, unlike some lighter elements, chemical shifts in the Lα1 X-ray fluorescence energy can be safely neglected, so that mercury Lα1 HERFD–XAS can be treated simply as a high-resolution version of conventional XAS. We present spectra of a range of mercury compounds that may be relevant to the environmental and life science research and show that density functional theory can produce adequate simulations of the spectra. We discuss strengths and limitations of the method and quantitatively demonstrate improvements both in speciation for complex mixtures and in background rejection for low concentrations.

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X‐Ray Spectroscopy Calculations within Kohn–Sham DFT: Theory and Applications

Cited by 5 publications

References 128 publications

A periodic energy decomposition analysis method for the investigation of chemical bonding in extended systems

A periodic energy decomposition analysis method for the investigation of chemical bonding in extended systems

Sulfur X-ray Absorption and Emission Spectroscopy of Organic Sulfones

Mercury Lα1 High Energy Resolution Fluorescence Detected X-ray Absorption Spectroscopy: A Versatile Speciation Probe for Mercury

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