Accuracy of XAS theory for unraveling structural changes of adsorbates: CO on Ni(100)

Diesen, Elias; Rodrigues, Gabriel L. S.; Luntz, A. C.; Abild‐Pedersen, Frank; Pettersson, Lars G. M.; Voss, Johannes

doi:10.1063/5.0028002

Cited by 7 publications

(6 citation statements)

References 38 publications

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“…In contrast the Z + 1 approximation does predict the correct order (with the exception of CH 3 OH and CH 3 Cl which are very close in energy) with a MAD of 0.14 eV. This is consistent with previous findings that have highlighted the merits of the Z + 1 approach 68 …”

Section: X‐ray Photoelectron Spectroscopysupporting

confidence: 90%

“…In the Z + 1 approximation, the core‐ionized state is described by the system where the core‐ionized atom is replaced by the valence ionized atom with one greater nuclear charge 65 . This approach has been shown to be successful in predicted the core‐level energy shifts, and studies detailing comparison with ΔSCF calculations have been reported 66‐68 . Table 3 shows computed core‐level shifts for the carbon atom in a range of chemical environments and compares the core‐level shifts determined from the Kohn–Sham (‐ε i KS ) and Hartree–Fock (‐ε i HF ) eigenvalues and the Z + 1 approximation with those from ΔSCF.…”

Section: X‐ray Photoelectron Spectroscopymentioning

confidence: 99%

“…65 This approach has been shown to be successful in predicted the core-level energy shifts, and studies detailing comparison with ΔSCF calculations have been reported. [66][67][68] Table 3 shows computed core-level shifts for the carbon atom in a range of chemical environments and compares the core-level shifts determined from the Kohn-Sham (-ε i KS ) and Hartree-Fock (-ε i HF ) eigenvalues and the Z + 1 approximation with those from ΔSCF. The results show that both Kohn-Sham and Hartree-Fock eigenvalues do not predict the correct order of core-level shifts, with a MAD of 0.56 eV for the DFT calculations.…”

Section: Other Approaches To Determining Core-ionization Energiesmentioning

confidence: 99%

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Modeling of the spectroscopy of core electrons with density functional theory

Besley

2021

WIREs Comput Mol Sci

100

104

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The availability of X‐ray light sources with increased resolution and intensity has provided a foundation for increasingly sophisticated experimental studies exploiting the spectroscopy of core electrons to probe fundamental chemical, physical, and biological processes. Quantum chemical calculations can play a critical role in the analysis of these experimental measurements. The relatively low computational cost of density functional theory (DFT) and time‐dependent density functional theory (TDDFT) make them attractive choices for simulating the spectroscopy of core electrons. An overview of current developments to apply DFT and TDDFT to study the key techniques of X‐ray photoelectron spectroscopy, X‐ray absorption spectroscopy, X‐ray emission spectroscopy, and resonant inelastic X‐ray scattering is presented. Insight into the accuracy that can be achieved, in conjunction with an examination of the limitations and challenges to modeling the spectroscopy of core electrons with DFT is provided. This article is categorized under: Electronic Structure Theory > Ab Initio Electronic Structure Methods Theoretical and Physical Chemistry > Spectroscopy Electronic Structure Theory > Density Functional Theory

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Section: X‐ray Photoelectron Spectroscopysupporting

confidence: 90%

Section: X‐ray Photoelectron Spectroscopymentioning

confidence: 99%

Section: Other Approaches To Determining Core-ionization Energiesmentioning

confidence: 99%

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Modeling of the spectroscopy of core electrons with density functional theory

Besley

2021

WIREs Comput Mol Sci

100

104

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“…To interpret the time evolution of the spectra, we perform density functional theory (DFT) calculations using the Quantum ESPRESSO [42,43] code, with spectra calculated using the xspectra [44][45][46] code. The general method for spectral calculation and treatment of the core-hole has been described elsewhere [47]. A 4 × 4 × 4 periodic slab was used for all spectrum calculations with a single CO molecule adsorbed at an on-top site, corresponding to ¼ ML coverage instead of the experimental 0.66 ML.…”

mentioning

confidence: 99%

Ultrafast Adsorbate Excitation Probed with Subpicosecond-Resolution X-Ray Absorption Spectroscopy

Diesen¹,

Wang²,

Schreck³

et al. 2021

Phys. Rev. Lett.

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We use a pump-probe scheme to measure the time evolution of the C K-edge x-ray absorption spectrum from CO=Ruð0001Þ after excitation by an ultrashort high-intensity optical laser pulse. Because of the short duration of the x-ray probe pulse and precise control of the pulse delay, the excitation-induced dynamics during the first picosecond after the pump can be resolved with unprecedented time resolution. By comparing with density functional theory spectrum calculations, we find high excitation of the internal stretch and frustrated rotation modes occurring within 200 fs of laser excitation, as well as thermalization of the system in the picosecond regime. The ∼100 fs initial excitation of these CO vibrational modes is not readily rationalized by traditional theories of nonadiabatic coupling of adsorbates to metal surfaces, e.g., electronic frictions based on first order electron-phonon coupling or transient population of adsorbate resonances. We suggest that coupling of the adsorbate to nonthermalized electron-hole pairs is responsible for the ultrafast initial excitation of the modes.

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“…In spite of successful application to large molecules [45][46][47] and extended systems, [48][49][50] TP-DFT is essentially a ground state theory for XAS. A different approach is to use the equation of motion describing the linear response of the electron system to an applied electromagnetic field.…”

Section: Linear Response Methodsmentioning

confidence: 99%

Core-hole delocalization for modeling X-ray spectroscopies: A cautionary tale

Brumboiu

Fransson

2022

Preprint

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The influence of core-hole delocalization for X-ray photoelectron, X-ray absorption, and X-ray emission spectrum calculations is investigated in detail, using approaches including response theory, transition-potential methods, and ground state schemes. The question of a localized/delocalized vacancy is relevant for systems with symmetrically equivalent atoms, as well as near-degeneracies which can distribute the core-orbitals over several atoms. We show that issues relating to core-hole delocalization are present for calculations considering explicit core-hole states, e.g. when using a core-excited or core-ionized reference state, or for fractional occupation numbers. Including electron correlation eventually alleviates the issues, but even using CCSD(T) there is a noticable discrepancy between core-ionization energies obtained with a localized and delocalized core-hole (0.5 eV for the carbon K-edge). Within density functional theory, the discrepancy is associated with the exchange interaction involving the core orbitals of the same spin symmetry as the delocalized core-hole, and the size of the error is thus directly related to the amount of HF exchange included in the functional. For linear response methods, we further show that if X-ray absorption spectra are modelled by considering symmetry-unique sets of atoms, care has to be taken such that there are no delocalizations of the core orbitals, which would otherwise introduce shifts in absolute energies and relative features.

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Accuracy of XAS theory for unraveling structural changes of adsorbates: CO on Ni(100)

Cited by 7 publications

References 38 publications

Modeling of the spectroscopy of core electrons with density functional theory

Modeling of the spectroscopy of core electrons with density functional theory

Ultrafast Adsorbate Excitation Probed with Subpicosecond-Resolution X-Ray Absorption Spectroscopy

Core-hole delocalization for modeling X-ray spectroscopies: A cautionary tale

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