A discrete variational method study on the electronic structures of CaMnO3and LaMnO3

The electronic structures of the perovskite oxides, LaMnO3 and CaMnO3, with various magnetic structures are studied using the first-principles discret e variational (DV) cluster method based on ab initio local-spin-density app roximation (LSDA). The ground states of different magnetic phases (includin g ferromagnetic (FM), A-type antiferromagnetic (A-AFM), and G-type antiferr omagnetic (G-AFM)) have been described in this work. The cubic CaMnO3 with observed G-AFM magnetic order is found to have a 0.1eV calculated gap. Both FM CaMnO3 and LaMnO3 have "half-metallic" character, which is in agreement with other works. LaMnO3 with both A-type and G-type antiferromagnetic ord er have metallic band structures. Part of Jahn-Teller (JT) distortion (Q(2) type) has been taken into consideration for A-AFM LaMnO3. Under Q(2) type JT distortion, the occupied and unoccupied states of O 2p and Mn 3d states move farther away from the Fermi energy. It is also found that the distorti on can further stabilize the structure. The density of states and the bindi ng energy of the distorted A-AFM LaMnO3 are given in this paper.