Spin-polarized linear muffin-tin orbitals calculation of the interstitial-atom effect in gamma'-Fe(4)Z (Z=H, C, N)

The spin-polarized linear muffin-tin orbitals method is applied to calculate the electronic structure of gamma'-Fe(4)Z (Z=H, C, N) and the gamma'-Fe(4)E which is gamma'-Fe with an empty sphere insertion. The chemical bonding effects of the interstitial Z atom are substantially investigated. The results indicate that the insertion of the Z atom changes not only the Fe-Fe interaction, but also the Fe-Z interaction. The latter is observed to be depending on the chemical properties of the Z atom. It can be concluded that, based upon our results, the interstitial chemical bonding effect in Fe(4)Z, which is related to the Fe-Z bonds, is mainly determined by the covalent feature of the Fe-Z bonds. The volume dependence of the magnetic moment (mu(Loc)), the Fermi-contact hyperfine fields (H-FC) the isomer shifts (IS) at Fe sites in gamma'-Fe4N and in gamma'-Fe(4)E, is calculated, respectively. The contributions of the magneto-volume effect and the chemical bonding effect of the N atom to mu(Loc), H-FC, and IS, are also reported.