SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 89: Poster Session VII: Organic molecules on inorganic substrates: electronic, optical and other properties III
O 89.6: Poster
Donnerstag, 4. März 2021, 10:30–12:30, P
Nuts and bolts of core-hole constraint based ab-initio simulations for K-shell x-ray photoemission and absorption spectra — •Benedikt P. Klein1,2, Samuel J. Hall1, and Reinhard J. Maurer1 — 1Department of Chemistry, University of Warwick, Coventry, United Kingdom — 2Diamond Light Source, Didcot, United Kingdom
X-ray Photoemission (XPS) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy are important tools used to study the electronic structure of materials and surfaces. Here, ab-initio simulations can help with the interpretation of complex spectra consisting of overlapping signatures. Approximate core-hole constraint based simulation methods using Density Functional Theory (DFT) such as the Delta-Self-Consistent-Field (ΔSCF) method or the transition potential (TP) method are widely employed to predict the K-shell XPS and NEXAFS spectra for a wide range of systems at reliable accuracy and affordable computational cost. We present our variants of both the ΔSCF and the TP method (coined ΔIP-TP) by applying them to exemplary molecules in the gas-phase, in molecular crystals, and at metal-organic interfaces. Thereby we systematically assess how practical simulation choices affect the stability and accuracy of the calculated transitions, which we compare to experimental data. The investigated choices include the exchange-correlation functional, the basis set, the method of core-hole localization, and the use of periodic boundary conditions. For the benefit of practitioners in the field, we discuss sensible default choices and limitations of the methods.