Calculation of Neutron and X-Ray Scattering Amplitudes for bcc Iron

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Abstract
The charge and spin densities for bcc iron were obtained from Bloch wave functions calculated by the augmented-plane-wave (APW) method. An iterative spin-dependent Hartree-Fock-Slater calculation was carried out and was found to yield a total spin per unit cell considerably in excess of the experimental value. The APW method was also applied to the potential of Wakoh and Yamashita, and the x-ray and neutron-scattering amplitudes were calculated from the resulting charge and spin densities for direct comparison with experiment. The neutron amplitudes are in reasonable agreement with experiment, and the calculated spin density confirms the existence of a region of negative magnetization density which has been inferred from experiment. The x-ray amplitudes for paired reflections indicate a much more nearly spherical charge distribution than do the experimental values. The sensitivity of these results to the potential used and the question of self-consistency have been investigated.