Periodic Reporting for period 1 - THEOCORPES (Theoretical Methods for Better Core Level Photoelectron Spectroscopy)
Periodo di rendicontazione: 2021-08-01 al 2023-07-31
Core level X-ray Photoelectron Spectroscopy (XPS) is an analytical technique for determining the chemical compositions of surfaces. It is widely used in both the academia and the industry. XPS is one of the primary methods used to study the fundamental mechanisms of processes such as heterogeneous catalysis, corrosion, and the preparation of protective or functional surface coatings. However, the analysis of recorded XPS spectra is sometimes very challenging. The aim of this project was to develop new and improved computational methods for modelling core level XPS, to enable XPS users to extract more useful information from their measurements.
This project was mainly focused on developing and extending the scope of the Δ-Self-Consistent-Field (ΔSCF) method for predicting core electron binding energies. In particular, work has been underway to enable ΔSCF calculations of core electron binding energies in a wider range of chemical elements that what was previously possible. Another key aim has been to further develop computational methods for modelling core level XPS in solids. In addition, together with collaborators, the ΔSCF approach and other computational methods have been used to aid the analysis and interpretation of experimental XPS measurements.
(i) The prediction of absolute core electron binding energies in elements of the first transition series has been demonstrated. (ii) An improved method for predicting absolute core electron binding energies in solids has been presented – this method combines the ΔSCF approach with the GW method from many-body perturbation theory. (iii) Computational methods have been used to analyze in detail the photoelectron spectrum of tungsten metal. (iv) In collaboration with J. Lischner from Imperial College London, an approach for predicting X-ray absorption spectra (XAS) of molecules that combines the ΔSCF approach with time-dependent density functional theory has been developed. (v) Results from this project have been presented at major international conferences and workshops including the 2023 March meeting of the American Physical Society, the Psi-k 2022 conference in Lausanne, and the Faraday discussion on photoelectron spectroscopy and the future of surface analysis, London 2022.