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HL: Fachverband Halbleiterphysik
HL 26: Focus Session: Frontiers of Electronic-Structure Theory IV (joint session O/HL)
HL 26.5: Talk
Wednesday, March 29, 2023, 12:00–12:15, TRE Ma
Scaling the Way for All-Electron XPS Simulations to CalculateAbsolute Binding Energies of Surface Superstructures — •Dylan Morgan1, Sam Hall1, Benedikt Klein1,2, Matthew Stoodley1,2, and Reinhard Maurer1 — 1Department of Chemistry, University of Warwick, United Kingdom — 2Diamond Light Source, Harwell Science and Innovation Campus, United Kingdom
First principles simulations of x-ray photoemission spectroscopy (XPS) and near-edge x-ray absorption fine-structure (NEXAFS) crucially support the assignment of surface spectra composed of many overlapping signatures. Core-level constrained Density Functional Theory calculations based on the Δ-SCF method are commonly used to predict relative XPS binding energy (BE) shifts but often fail to predict absolute BEs. The all-electron numeric atomic orbital code FHI-aims enables an accurate prediction of absolute BEs, but the legacy code lacked computational scalability to address large systems and robustness with respect to localisation of the core hole. We present a redesign of the core-hole constrained code in FHI-aims that delivers improvements to the scalability and robustness of core-hole constrained calculations in FHI-aims. We demonstrate the improved scaling behaviour and employ the new code to simulate core-level spectroscopic fingerprints of graphene moire superstructures. The code refactorisation forms the basis to expand the code towards improved core hole localisation methods and the rigorous treatment of relativistic effects for core-level spectra beyond the 1s shell.