The Fe-I sites are at the cube corners and have cubic symmetry with three 4-fold rotation axes along the x, y, and z directions, which makes the asymmetry parameter eta = 0. The Fe-II sites, which are located at the face centers, have lower symmetry, with one 4-fold axis along the z-direction and two 2-fold axes in the x-y plane. This means that the PAS for Fe-II would be along four-fold axis