Probing surface reactions via core-level shifts
|Scientific Discipline||Materials science, surface chemistry|
|Principal Investigator(s)||Matthias Krack, Michele Parrinello|
The importance of pyrite (FeS2) in a variety of industrial, geochemical, photochemical, and environmental processes necessitates a thorough understanding of its reactivity which strongly depends on its surface defects. The main goal of the proposed research project is to establish a direct link between theoretically predicted surface sites and experimental data retrieved from X-ray photoemission spectra (XPS). The project will focus on the precise calculation of the Fe 2p and S 2p core-level shifts (CLS) of various pyrite (100) surface sites including defect sites. We expect that our methodology will prove to be a very useful computational tool to characterize surface metal sites and to follow chemical changes by identifying the alterations in the oxidation and hybridization state of the surface atoms. In this way, it will be feasible to identify unambiguously the experimentally observed surface sites involved in the reactions on pyrite surfaces. We plan to calculate the Fe 2p and S 2p CLS using a newly developed all-electron ab-initio electronic structure approach based on Kohn-Sham density functional theory (DFT) as implemented in the CP2K/Quickstep code. The planned all-electron calculations for realistic pyrite model systems will be very demanding. Fortunately, the excellent scalability of Quickstep on current parallel computers has already been proven and the projected calculations will become feasible due to the exceptional resources provided by DEISA.