Abstract
In this paper, we report structural parameters, magnetic ordering and the electronic structure of the tetragonal and orthorhombic ternary iron arsenide compound BaFe(2)As2. Ab initio calculations are performed by the means of full-potential linearized augmented plane waves plus local orbitals method for both spin states. The local spin density plus Hubbard potential (LSDA + U) and generalized gradient plus Hubbard potential (GGA+U) approximations are used to treat the exchange and correlation potentials. The results mainly show that orthorhombic BaFe2As2 compound has an antiferromagnetic spin ordering. Both spin-up and spin-down polarizations are considered to investigate the band structure, density of states and electron charge density. High density of states population at the Fermi level reveals metallic character of this material. The magnetism property arises essentially from the 3d orbital of iron atom.