Theoretical Prediction of Core Electron Binding Energies in Solids, Surfaces and Molecules

Core level X-ray Photoelectron Spectroscopy (XPS) is one of the most widely used experimental techniques in the study of materials and molecules. The key quantity in the analysis of experimental spectra is the core electron binding energy. Measured binding energies allow the identification of the elemental composition of the probed region, and small shifts in binding energies can also be used to make inferences about the local chemical environments of the atoms. However, this information can be difficult to interpret, especially for complex systems.

First principles calculations provide an alternative way to link the core electron binding energy of an atom to its chemical environment. Previously, we have shown how Δ-Self-Consistent-Field (Δ-SCF) calculations can predict absolute core electron binding energies in small molecules with extremely hight accuracy (errors < 0.2 eV). We have also shown how this method can be extended to solids and surfaces via the use of cluster models. [Kahk and Lischner, Phys. Rev. Materials 3, 100801(R) (2019)]

In this talk, the prediction of core electron binding energies in periodic solids will be discussed further, and the finite cluster approach will be constrasted to the periodic supercell approach with representative examples.