title: Electronic structure and energetics of tetragonal SrCuO₂ and its high-pressure superstructure phase.
abstract: First-principles calculations have been used to investigate the electronic structure and energetics of the simple tetragonal SrCuO₂ (P4=mmm) and its high-pressure tetragonal superstructure (P4=mmm). Based on the calculations, the high-pressure phase is metastable as compared with the low pressure tetragonal phase, with an energy difference of 0.13 eV per SrCuO₂ formula unit. The energy barrier to the transition from the superstructure to the simple tetragonal structure is 0.24 eV at 7 GPa; thus, high temperatures are required to synthesize the latter. Among the possible structural configurations resulting from the partially occupied oxygen site in the superstructure phase, the most stable structure has a space group PN4m2, reduced from that of the simple tetragonal structure P4=mmm. The detailed analysis of the electronic band structures of the simple tetragonal and superstructure phases suggests that the out-of-plane buckling of the O atoms in the superstructure leads to significant decrease in the O p-Cu d orbital overlap, allowing the energy of the system to be lowered, which is necessary for the structural stability. An understanding of the electronic structure and energetics of the high-pressure superstructure phase and its relation to the simple tetragonal phase provides a basis for exploring the physical properties of the infinite layer, high-TC superconductor.
authors: Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109, USA. jwwang@umich.edu
authors: Jianwei
authors: J
authors: Wang
authors: Zsolt
authors: Z
authors: Rak
authors: Fuxiang
authors: F
authors: Zhang
authors: Rodney C
authors: RC
authors: Ewing
authors: Udo
authors: U
authors: Becker