Structural determination and electronic properties of the 4d perovskite SrPdO3

The structure and ground state electronic structure of the recently synthesized SrPdO3 perovskite [A. Galal et al. J. Power Sources 195, 3806 (2010)] have been studied by means of screened hybrid functional and the GW approximation with the inclusion of electron-hole interaction within the test-charge/test-charge scheme. By conducting a structural search based on lattice dynamics and group theoretical method we identify the orthorhombic phase with P-nma space group as the most stable crystal structure. The phase transition from the ideal cubic perovskite structure to the P-nma one is explained in terms of the simultaneous stabilization of the antiferrodistortive phonon modes R-4(+) and M-3(+). Our results indicate that SrPdO3 exhibits an insulating ground state, substantiated by a GW(0) gap of about 1.1 eV. Spin polarized calculations suggest that SrPdO3 adopts a low spin state (t(2g)(up arrow down arrow up arrow down arrow up arrow down arrow)e(g)(0)), and is expected to exhibit spin excitations and spin state crossovers at finite temperature, analogous to the case of 3d isoelectronic LaCoO3. This would provide another playground for the study of spin state transitions in 4d oxides and an opportunity to design multifunctional materials based on the 4d P-nma building block.