When looking for possible rotation axes through the center of the cell it is clear that the EFG tensor of the Fe-I sites will be zero. This can be found by applying the second theorem. The reason for this being that there are at least three possible 4-fold rotation axes. The PAS can be chosen to lay in the direction of the arrow, through the center of the cell. This is not completely the case for the Fe-II sites. Here we find just one 4-fold rotation axis in the direction of the arrow and two 2-fold rotation axes perpendicular to this axis. This means that we can use the second point of the first theorem, which means that we will have axial symmetry around the z-axis of the PAS. With the z-axis chosen to be running through the center of the cell and in the direction of the arrow.