First-Principles Estimation of Core Level Shifts for Hf, Ta, W, and Re

Daniel Wolverson; Benjamin Smith; Enrico Da Como; Charles Sayers; Gary Wan; Luca Pasquali; Mattia Cattelan

doi:10.1021/acs.jpcc.2c00981

First-Principles Estimation of Core Level Shifts for Hf, Ta, W, and Re

J Phys Chem C Nanomater Interfaces. 2022 Jun 2;126(21):9135-9142. doi: 10.1021/acs.jpcc.2c00981. Epub 2022 May 24.

Authors

Daniel Wolverson¹, Benjamin Smith¹, Enrico Da Como¹, Charles Sayers¹, Gary Wan², Luca Pasquali³, Mattia Cattelan⁴

Affiliations

¹ Centre for Nanoscience and Nanotechnology and Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom.
² Centre for Nano Science and Quantum Information, University of Bristol, Tyndall Avenue, Bristol BS8 1FD, United Kingdom.
³ Department of Engineering, University of Modena and Reggio Emilia, Via Vivarelli 10, Modena 41125, Italy.
⁴ School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, United Kingdom.

Abstract

A simple first-principles approach is used to estimate the core level shifts observed in X-ray photoelectron spectroscopy for the 4f electrons of Hf, Ta, W, and Re; these elements were selected because their 4f levels are relatively close to the Fermi energy. The approach is first tested by modeling the surface core level shifts of low-index surfaces of the four elemental metals, followed by its application to the well-studied material TaSe₂ in the commensurate charge density wave (CDW) phase, where agreement with experimental data is found to be good, showing that this approach can yield insights into modifications of the CDW. Finally, unterminated surface core level shifts in the hypothetical MXene Ta₃C₂ are modeled, and the potential of XPS for the investigation of the surface termination of MXenes is demonstrated.