  Very recently, as an important step in the development of layered Fe-free
pnictide-oxide superconductors, the new phase BaTi2Bi2O was discovered which
has the highest TC (about 4.6 K) among all related non-doped systems. In this
Letter, we report for the first time the electronic bands, Fermi surface
topology, total and partial densities of electronic states for BaTi2Bi2O
obtained by means of the first-principles FLAPW-GGA calculations. The
inter-atomic bonding picture is described as a high-anisotropic mixture of
metallic, covalent, and ionic contributions. Besides, the structural and
electronic factors, which can be responsible for the increased transition
temperature for BaTi2Bi2O (as compared with related pnictide-oxides BaTi2As2O
and BaTi2Sb2O), are discussed.
