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Density Functional Theory Based Methods for the Calculation of X-ray Spectroscopy

Besley, Nicholas A.

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Authors

Nicholas A. Besley



Abstract

ConspectusThe availability of new light sources combined with the realization of the unique capabilities of spectroscopy in the X-ray region has driven tremendous advances in the field of X-ray spectroscopy. Currently, these techniques are emerging as powerful analytical tools for the study of a wide range of problems encompassing liquids, materials, and biological systems. Time-resolved measurements add a further dimension to X-ray spectroscopy, opening up the potential to resolve ultrafast chemical processes at an atomic level. X-ray spectroscopy encompasses a range of techniques which provide complementary information, and these include X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES), and resonant inelastic X-ray scattering (RIXS). In many studies, the interpretation of the experimental data relies upon calculations to enable the nature of the underlying molecular structure, electronic structure, and bonding to be revealed. Density functional theory (DFT) based methods are some of the most widely used methods for the simulation of X-ray spectra. In this Account, we focus on our recent contributions to the simulation of a range of X-ray spectroscopic techniques using DFT and linear-response time-dependent density functional theory (TDDFT) and show how these methods can provide a computational toolkit for the simulation of X-ray spectroscopy. The importance of the exchange-correlation functional for the calculation of XAS is discussed, and the introduction of short-range corrected functionals is described. The application of these calculations to study large systems through the use of efficient implementations of TDDFT will be highlighted, with the use of these methods illustrated through studies of ionic liquids and transition metal complexes. The extension of TDDFT to calculate XES through the use of a reference determinant for the core-ionized state will be described, and the factors that affect the accuracy of the computed spectra discussed. The application of these approaches will be illustrated through the study of a range of organic molecules and transition metal complexes, which also show how going beyond the dipole approximation in determining the transition intensities can be critical. The application of these approaches to the simulation of the RIXS spectrum of water will also be described, highlighting how ultrafast dynamics on the femtoscale time scale are evident in the measured spectra. In these calculations, the description of the core-ionized and core-excited states becomes increasingly important, and the role of the basis set in accurately describing these states will be explored.

Citation

Besley, N. A. (2020). Density Functional Theory Based Methods for the Calculation of X-ray Spectroscopy. Accounts of Chemical Research, 53(7), 1306-1315. https://doi.org/10.1021/acs.accounts.0c00171

Journal Article Type Article
Acceptance Date Apr 3, 2020
Online Publication Date Jul 2, 2020
Publication Date Jul 21, 2020
Deposit Date Jul 7, 2020
Publicly Available Date Mar 28, 2024
Journal Accounts of Chemical Research
Print ISSN 0001-4842
Electronic ISSN 1520-4898
Peer Reviewed Peer Reviewed
Volume 53
Issue 7
Pages 1306-1315
DOI https://doi.org/10.1021/acs.accounts.0c00171
Keywords General Chemistry; General Medicine
Public URL https://nottingham-repository.worktribe.com/output/4747486
Publisher URL https://pubs.acs.org/doi/10.1021/acs.accounts.0c00171
Additional Information This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Accounts of Chemical Research, copyright © American Chemical Society after peer review.To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.accounts.0c00171

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