title: Prediction of possible CaMnO3 modifications using an ab initio minimization data-mining approach.
abstract: We have performed a crystal structure prediction study of CaMnO3 focusing on structures generated by octahedral tilting according to group-subgroup relations from the ideal perovskite type (Pm\overline 3 m), which is the aristotype of the experimentally known CaMnO3 compound in the Pnma space group. Furthermore, additional structure candidates have been obtained using data mining. For each of the structure candidates, a local optimization on the ab initio level using density-functional theory (LDA, hybrid B3LYP) and the Hartree--Fock (HF) method was performed, and we find that several of the modifications may be experimentally accessible. In the high-pressure regime, we identify a post-perovskite phase in the CaIrO3 type, not previously observed in CaMnO3. Similarly, calculations at effective negative pressure predict a phase transition from the orthorhombic perovskite to an ilmenite-type (FeTiO3) modification of CaMnO3.
authors.affiliation: Materials Science Laboratory, Institute of Nuclear Sciences Vinča, Belgrade University, PO Box 522, 11001 Belgrade, Serbia.
authors.forename: Jelena
authors.initials: J
authors.lastname: Zagorac
authors.affiliation: Materials Science Laboratory, Institute of Nuclear Sciences Vinča, Belgrade University, PO Box 522, 11001 Belgrade, Serbia.
authors.forename: Dejan
authors.initials: D
authors.lastname: Zagorac
authors.affiliation: Department of Chemistry, University of Niš, Višegradska 33, 18000 Niš, Serbia.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Zarubica
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany.
authors.forename: J Christian
authors.initials: JC
authors.lastname: Schön
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany.
authors.forename: Katarina
authors.initials: K
authors.lastname: Djuris
authors.affiliation: Materials Science Laboratory, Institute of Nuclear Sciences Vinča, Belgrade University, PO Box 522, 11001 Belgrade, Serbia.
authors.forename: Branko
authors.initials: B
authors.lastname: Matovic
keywords: ceramics; perovskite; phase transitions; structure prediction