Gradient-corrected density functionals: Full-potential calculations for iron

Full-potential calculations of the electronic structure and ground-state properties of iron using the Langreth-Mehl-Hu, Perdew-Wang, and Becke gradient-corrected local-density functionals are reported. As in earlier linear-muffin-tin-orbital calculations using the atomic-spheres approximation, a ferromagnetic bcc ground state is found, although there are differences in the energetics. The effect of the gradient corrections on the electronic structure is discussed in detail. It is found that there are significant changes in the exchange splittings that result from nonspherical terms in the potential, and these differ significantly depending on the choice of the gradient correction.