> Not violating symmetry restrictions you may either > have the sphere with the terms 11=22=33 and 12=13=23=0 > or something else allowing the 12=13=23 terms to be equal > but different from 0. These two possibilities are all you can do > in cubic symmetry with h,k,l permutable. If I am not wrong.
You are. The cross terms have disappear even at orthorhombic (monoclinic has only one). Cubic is an orthorhombic to which a 3-fold axis is added on the big diagonal resulting in 11=22=33. Nicolae
