High-pressure tuning of electronic structures, stability and mechanical properties of plutonium oxides: a DFT+U study

Plutonium (Pu) exhibits exceptionally complex fundamental physical properties, rendering its oxidation and corrosion behaviors a key research focus. Its valence electrons (especially 5f electrons) lie at the boundary of localization and delocalization, enabling easy formation of multiple oxides, while LDA/GGA conventional methods fail to capture the local effects of strong f-electron interactions - posing a major challenge for accurate elucidation of their electronic structures. Herein, we employed the DFT+U method to systematically investigate the electronic structures, structural stability, and mechanical properties of four high-temperature Pu oxides (β-Pu₂O₃, α-Pu₂O₃, PuO, and α-PuO₂) under 50-150 GPa. Results show that increasing pressure enhances electron delocalization of Pu oxides, reducing compressibility and improving ductility. During pressure-induced structural phase transitions, most oxides exhibit altered metallicity and stability, decreased chemical activity, and dominant Pu-O anti-bonding interactions. Electron contributions of different spin states depend on the oxide structure and type, and α-crystal systems of Pu oxides are more rigid than β-crystal systems, with weaker bond coordination and stronger delocalization. This work provides novel insights into pressure-modulated structure-property relationships of Pu oxides, laying a theoretical foundation for understanding 5f electron correlation effects and guiding the design of Pu-based materials under extreme conditions.