Efficient and Accurate Theoretical Simulation on X-ray Photoelectron Spectroscopy for Iron Compounds

X-ray photoelectron spectroscopy (XPS) is a widely used technique in material characterization, enabling the acquisition of chemical information by measuring the core-level electron binding energy (BE) of target elements. Theoretical simulations of XPS typically provide a streamlined and condition-free methodology for obtaining material XPS data. However, for iron-based systems, the complex magnetic properties, strong electron-electron correlation interactions, and the absence of standard sample pose a significant challenge to establish an efficient and accurate simulation approach. This work introduces a high-throughput framework designed for the standardization and efficient calculation of the Fe 2p core-level BE shifts. With this framework, the reliability of the theoretical method was comprehensively evaluated, encompassing an all-electron extension of the delta self-consistent field method and orbital energy approximation methods based on the pseudopotential. Furthermore, a series of standard samples of iron compounds were prepared under ultrahigh-vacuum conditions to provide measured XPS values as references to evaluate the theoretical simulations. Through this evaluation, the FSn method with the PBE functional was established as the most suitable for simulating XPS in iron-based materials, demonstrating a remarkable accuracy with an error of merely 0.02 eV. Our methodology offers a standardized approach for the analysis of iron compounds, laying the groundwork for quantitative analysis of more complex systems in future investigations.