3.2 Part I: Enumeration of Shells with ||n||² < 14
Proof (Part I):
We systematically enumerate all integer triples (n
x
, n
y
, n
z
) with norm-
squared less than 14. For computational efficiency, we consider
representatives up to permutation and sign, noting that if (a,b,c) is in a shell,
so are all permutations {a,b,c} and all sign combinations {±a, ±b, ±c}.
||n||² Representative n Shell Type Reason NOT Fully Anisotropic
1 (1,0,0) Axial Two components are zero
1 (0,1,0) Axial Two components are zero
1 (0,0,1) Axial Two components are zero
2 (1,1,0) Planar One component is zero
2 (1,0,1) Planar One component is zero
2 (0,1,1) Planar One component is zero
3 (1,1,1) Cubic (spatial) All components equal: 1=1=1
4 (2,0,0) Axial Two components are zero
5 (2,1,0) Planar One component is zero
6 (2,1,1) Spatial (repeated)Two components equal: 1=1
8 (2,2,0) Planar One component is zero
9 (3,0,0) Axial Two components are zero
9 (2,2,1) Spatial (repeated)Two components equal: 2=2
Part II: Verify that none satisfy the fully anisotropic condition▸
Part III: Verify that n = (1,2,3) satisfies the condition▸