First‐principles calculations on the energetics, electronic structures and magnetism of SrFeO 2

The electronic and magnetic properties of SrFeO 2 with different magnetic configurations have been calculated via the plane‐wave pseudopotential density functional theory method, using the experimental lattice parameters. The results give an antiferromagnetic ground state for SrFeO 2 with an absolute magnetic moment agreeing very well with the experimental report. In comparison with the counterparts whose magnetic moments are parallel to the c axis, the structures with spin moments parallel to the a (or b ) axis exhibit no observable preference in total energy, but show different density distributions of the Fe 3 d   x   2 − y   2and Fe 3 d   z   2states. The square‐planar crystal field splits the Fe 3 d orbitals into a high‐level d   x   2 − y   2, a low d   z   2, and intermediate d xy and d xz or d yz components. The exchange splitting is larger than the crystal‐field splitting, resulting in the high‐spin Fe 3d states. Referred to the triplet O 2 , the O‐vacancy formation energy from SrFeO 3 to SrFeO 2 has been deduced as well, along with its dependence on the temperature and O 2 partial pressure. © 2009 Wiley Periodicals, Inc. J Comput Chem 2009