Electronic structure of BaIrO3:: A first-principles study using the local spin density approximation

We investigate the electronic structure of BaIrO3, an interesting compound exhibiting charge density wave transition in its insulating phase and ferromagnetic transition at the same temperature, using full potential linearized augmented plane wave method within the local spin density approximations. The ferromagnetic ground state could exactly be described in these calculations and the calculated spin magnetic moment is found to be small as observed in the magnetic measurements. Interestingly, no signature of exchange splitting is observed in the density of states corresponding to Ir 5d and/or any other electronic states. The small spin moment appears essentially due to unequal population of the up- and down-spin Ir 5d bands. Comparison of the valence band density of states with the experimental spectral functions suggests that a rigid shift of the Fermi level towards higher energies in the calculated density of states provides a good description of the experimental spectra. This indicates that the intrinsic oxygen nonstoichiometry leads to electron doping in the system and plays the primary role in determining the electronic structure rather than the electron correlation effects as often observed in other systems. The calculated results for Ba 5p core levels show that the Madelung potential of one of the three nonequivalent Ba atoms is different from that of other two as predicted in the recent experiments.