  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 non-stoichiometry 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 non-equivalent Ba atoms is
different from that of other two as predicted in the recent experiments.
