Structure and stability investigation of oxygen interaction with Fe in bcc-Fe

The precise interaction mechanisms between body-centered cubic Fe and the unavoidable interstitial O atom are critical to understanding oxidation resistance. Even though the Fe-O interaction has been investigated exten-sively for centuries, the physical evolution processing including the stability, bonding characteristics, and magnetism, remains as one of the most important scientific issues. Here, a four-level (atomic, electronic, orbital, and spin-level) analysis was employed to investigate the precise interactions between Fe and O atoms by multiple complementarity methods (Madelung energy calculation, electronic density analysis, crystal orbital Hamilton population analysis and topology analysis of spin maps). The stability of Fe atoms was enhanced with the O atom at the tetrahedral interstitial site. The bonding strength between Fe and O atoms originates substantially from s orbits. Furthermore, the topology of the minority-spin was changed by the magnetic moment flip of O, and the interaction among Fe atoms were strengthened. A further understanding of the Fe-O mechanism provides a theoretical basis for obtaining excellent physical properties in Fe-based materials.