All ab initio calculations of spiral spin density waves heretofore have used the atomic sphere approximation (ASA) in which not only is the potential assumed spherical but also the direction of magnetization is taken constant within each Wigner-Seitz sphere. We have performed full potential local density approximation calculations for γ-Fe spiral spin density waves with wave vector $\mathbf{q}=(2\mathrm{}\pi /a)(0,0,\alpha )$ and $\mathbf{q}=(2\mathrm{}\pi /a)(\gamma ,0,1),$ finding the ground state at $\alpha \approx \mathrm{0.55.}$ The results differ quantitatively but not qualitatively from those of ASA calculations. However, interesting results are obtained for the azimuthal angle of the magnetization $\phi \left(\mathbf{r}\right)=\mathbf{q}\cdot \mathbf{r}+\hat{\phi }\left(\mathbf{r}\right),$ where $e^{i\hat{\phi }\left(\mathbf{r}\right)}$ is a function with the lattice periodicity which is calculated self-consistently.

• Received 28 April 1998

DOI:https://doi.org/10.1103/PhysRevB.58.9207