Recent advances in modelling core-electron spectroscopy
This themed collection includes a series of articles on recent advances in theory, software, and analysis tools for modelling core-electron spectroscopy.
Perspective
Computational approaches for XANES, VtC-XES, and RIXS using linear-response time-dependent density functional theory based methods
Time-dependent density functional theory provides a sufficiently accurate framework to study X-ray spectroscopies.
Ab initio calculation of X-ray and related core-level spectroscopies: Green's function approaches
Green's function approaches facilitate efficient and accurate calculations of X-ray spectra that include key many-body effects.
Advances in the OCEAN-3 spectroscopy package
An overview of the OCEAN code for calculating near-edge X-ray spectroscopy, including X-ray absorption and resonant inelastic X-ray scattering, using the Bethe-Salpeter equation approach.
Paper
Sensitivity of Kβ mainline X-ray emission to structural dynamics in iron photosensitizer
The sensitivity of metal K-edge X-ray emission spectroscopy to ultrafast structural dynamics is explained by a multiconfigurational wavefunction model. This provides a new path to interpret spectra of non-equilibrium structures in photochemistry.
Paper
Quantifying vibronic coupling with resonant inelastic X-ray scattering
Electron–phonon interactions are fundamental to the behavior of chemical and physical systems.
Paper
Disentangling the resonant Auger spectra of ozone: overlapping core-hole states and core-excited state dynamics
Resonant and non-resonant Auger spectra of ozone are investigated with a multi-reference scheme based on the one-center approximation. The role of core-excited state dynamics and overlapping core-hole states are elucidated.
Paper
Probing disorder in 2CzPN using core and valence states
Gas phase structures of 2CzPN extracted from molecular dynamics are used to investigate the effects of disorder on the core and valence states using density functional theory, and compared to experimental X-ray photoelectron spectroscopy.
Revisiting the K-edge X-ray absorption fine structure of Si, Ge–Si alloys, and the isoelectronic series: CuBr, ZnSe, GaAs, and Ge
Extended X-ray absorption fine structure (EXAFS) has evolved into an unprecedented local-structure technique that is routinely used to study materials’ problems in the biological, chemical, and physical sciences.
Accurate core excitation and ionization energies from a state-specific coupled-cluster singles and doubles approach
A proper treatment of orbital relaxation and correlation, while addressing spin contamination and the shortcomings of the CVS, allows ΔCCSD to reach errors smaller than 0.5 eV compared to experimental X-ray absorption excitation energies.
Paper
All-electron many-body approach to resonant inelastic X-ray scattering
An all-electron Bethe–Salpeter equation framework reveals the interplay of correlation and coherence in the resonant inelastic X-ray scattering in solids.
Extended quasiparticle approach to non-resonant and resonant X-ray emission spectroscopy
X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS) are good target of extended quasiparticle theory which is applicable to any initial excited eigenstate. Application of GW with/without BSE is guaranteed by this theory.
Benchmark relativistic delta-coupled-cluster calculations of K-edge core-ionization energies of third-row elements
A benchmark computational study of K-edge core-ionization energies of third-row elements using relativistic delta-coupled-cluster (ΔCC) methods and a revised core valence separation (CVS) scheme is reported.
Paper
Using core-hole reference states for calculating X-ray photoelectron and emission spectra
A protocol for removing near-singularities in post-HF calculations of core-ionization energies and X-ray emission spectra is presented, enabling highly reliable calculations of such properties for large molecules and when using large basis sets.
Relativistic nonorthogonal configuration interaction: application to L2,3-edge X-ray spectroscopy
In this article, we develop a relativistic exact-two-component nonorthogonal configuration interaction (X2C-NOCI) for computing L-edge X-ray spectra.
Paper
Beyond structural insight: a deep neural network for the prediction of Pt L2/3-edge X-ray absorption spectra
A deep neural network is developed to predict and understand the electronic and geometric characteristics of an X-ray absorption spectrum at the L2/3-edge.
Advances in modelling X-ray absorption spectroscopy data using reverse Monte Carlo
Tridimensional models of molecules, crystalline solids and liquids have been are obtained by Reverse Monte Carlo (RMC) using multiple-edge x-ray absorption spectroscopy and diffraction or MD. Full details on method and applications are presented.
Paper
Time-resolved study of recoil-induced rotation by X-ray pump – X-ray probe spectroscopy
We propose two color X-ray pump–probe spectroscopy, which opens new perspectives in studies of molecular rotational dynamics induces by the recoil effect in real-time. The feasibility of experimental observation is also discussed.
Simple renormalization schemes for multiple scattering series expansions
Renormalization schemes for improving the convergence of multiple scattering series expansions are studied. Numerical tests on a small Cu(111) cluster show that convergence rates can double or even that a divergent series can eventually converge.
Solving the structure of “single-atom” catalysts using machine learning – assisted XANES analysis
Quantitative structural information of the single-atom catalyst was obtained by machine learning-assisted XANES data analysis.
Resolving competing conical intersection pathways: time-resolved X-ray absorption spectroscopy of trans-1,3-butadiene
Time-resolved X-ray absorption spectroscopy is a particularly sensitive probe of nonadiabatic molecular wave packet dynamics.
About this collection
Core electron spectra have been extremely useful probes of the local atomic and electronic structure and dynamics of materials, due to their local, element-specific nature. These phenomena include X-ray photoemission (XPS), X-ray absorption (XAS), X-ray emission (XES), electron energy loss spectroscopy (EELS), Auger electron spectroscopy (AES), and resonant inelastic X-ray scattering (RIXS).
The theoretical treatment of these processes requires diverse modelling techniques for excited states, dynamic response, and thermodynamic behavior which are material-specific and capture the effects of many-electron interactions and inelastic processes. Examples range from Green’s function methods, such as GW or the Bethe-Salpeter equation to quantum-chemistry techniques and extensions of density-functional theory (DFT) such as TDDFT.
In recent years, there has been a rapid development of these approaches which have become highly quantitative, driven in part by complementary advances in computation and experimental precision. This themed collection in PCCP showcases research in all aspects of the theory and computational techniques relevant to core-electron spectroscopy.
Guest edited by John J. Rehr (University of Washington, USA), David Prendergast (Lawrence Berkeley National Laboratory, USA) and Johannes Lischner (Imperial College London, UK).