Magnetic structure and orbital ordering in BaCoO3 from first-principles calculations

Ab initio calculations using the $\mathrm{APW}+\mathrm{lo}$ method as implemented in the WIEN2k code have been used to describe the electronic structure of the quasi-one-dimensional system $\mathrm{Ba}\mathrm{Co}{\mathrm{O}}_{3}$. Both, GGA and $\mathrm{LDA}+U$ approximations were employed to study different orbital and magnetic orderings. GGA predicts a metallic ground state whereas $\mathrm{LDA}+U$ calculations yield an insulating and ferromagnetic ground state (in a low-spin state) with an alternating orbital ordering along the Co-Co chains, consistent with the available experimental data.