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MM: Fachverband Metall- und Materialphysik

MM 39: Hydrogen in Materials II

MM 39.7: Vortrag

Freitag, 13. März 2026, 12:00–12:15, SCH/A215

Hydrogen induced small polarons in iron oxides using occupation-matrix control DFT+U calculations — Ahmed Abdelkawy, •Mira Todorova, and Jörg Neugebauer — Max Planck Institute for Sustainable Materials, Max-Planck-Str.1, 40470 Düsseldorf

Over 6% of global CO₂ emissions come from using carbon-based reducing agents in iron production. Replacing these agents with hydrogen would result in water as the sole byproduct, thereby reducing harmful emissions. To understand H-based reduction of iron oxides, we focus on hydrogen interactions with bulk hematite (Fe₂O₃). Modeling transition metal oxides is challenging because conventional DFT-GGA has self-interaction errors and inadequately treats the Coulomb repulsion in partially filled d-orbitals. Corrections such as DFT+U or exchange-correlation functionals, which incorporate a fraction of the exact exchange, further complicate matters because they generate a multitude of metastable configurations that DFT cannot predict. In this study, we use DFT+U with occupation matrix control to map the energy landscape of the small electron polaron generated by H interstitials. We construct the three-dimensional potential energy surface of H interstitials using the resulting ground-state configurations. This enables us to gain detailed insight into hydrogen kinetics and rate-limiting steps.

Keywords: Hematite; DFT+U; H based reduction of iron oxides; potential energy surface