The structure and ground state electronic structure of the recently synthesized SrPdO${}_3$ 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 SrPdO${}_3$ exhibits an insulating ground state, substantiated by a GW${}_0$ gap of about 1.1 eV. Spin polarized calculations suggest that SrPdO${}_3$ adopts a low spin state ($t_{2g}^{\uparrow \downarrow \uparrow \downarrow \uparrow \downarrow }{e}_g^0$), and is expected to exhibit spin excitations and spin state crossovers at finite temperature, analogous to the case of 3$d$ isoelectronic LaCoO${}_3$. This would provide another playground for the study of spin state transitions in 4$d$ oxides and an opportunity to design multifunctional materials based on the 4$d$ $P_{nma}$ building block.

• Received 27 August 2013
• Revised 9 December 2013

DOI:https://doi.org/10.1103/PhysRevB.89.045104