Electronic structure of the perovskite oxides La1-xSrxMnO3

The electronic structures of perovskite oxides La1-xSrxMnO3 are studied with local spin-density approximation (LSDA). Results show that the lowest energy is obtained when the Mn-O bond length is 1.95 A with ideal cubic crystal structure. This value of Mn-O bond length is consistent with the experimental data. Considering a proper tetragonal distortion of the crystal, the total energy of system becomes lower. A half-metal state can be got both for the undistorted structure (Mn-O bond lengths are 1.95-2.10 A) and the distorted structure. It is suggested that the effect of Jahn-Teller distortion is not the main reason of formation of half-metal state. However, the electronic properties are very sensitive to the c/a ratio. Along with the increase of c/a ratio, system transforms from metal to half metal and further the insulator