| Fdd2 | C2v19 | mm2 | Orthorhombic  |
| No. 43 | Fdd2 | Patterson symmetry Fmmm | |
Origin on 1 1 2
| Asymmetric unit | 0 ≤ x ≤ 1/4; 0 ≤ y ≤ 1/4; 0 ≤ z ≤ 1 |
Symmetry operations
For (0, 0, 0)+ set
| (1) 1 | (2) 2 0, 0, z | (3) d(1/4, 0, 1/4) x, 1/8, z | (4) d(0, 1/4, 1/4) 1/8, y, z |
For (0, 1/2, 1/2)+ set
| (1) t(0, 1/2, 1/2) | (2) 2(0, 0, 1/2) 0, 1/4, z | (3) d(1/4, 0, 3/4) x, 3/8, z | (4) d(0, 3/4, 3/4) 1/8, y, z |
For (1/2, 0, 1/2)+ set
| (1) t(1/2, 0, 1/2) | (2) 2(0, 0, 1/2) 1/4, 0, z | (3) d(3/4, 0, 3/4) x, 1/8, z | (4) d(0, 1/4, 3/4) 3/8, y, z |
For (1/2, 1/2, 0)+ set
| (1) t(1/2, 1/2, 0) | (2) 2 1/4, 1/4, z | (3) d(3/4, 0, 1/4) x, 3/8, z | (4) d(0, 3/4, 1/4) 3/8, y, z |
Generators selected (1); t(1, 0, 0); t(0, 1, 0); t(0, 0, 1); t(0, 1/2, 1/2); t(1/2, 0, 1/2); (2); (3)
Positions
| Multiplicity, Wyckoff letter, Site symmetry | Coordinates | Reflection conditions | |||||||
| (0, 0, 0)+ (0, 1/2, 1/2)+ (1/2, 0, 1/2)+ (1/2, 1/2, 0)+ | General: | ||||||||
|
| hkl : h + k, h + l, k + l = 2n 0kl : k + l = 4n, k, l = 2n h0l : h + l = 4n, h, l = 2n hk0 : h, k = 2n h00 : h = 4n 0k0 : k = 4n 00l : l = 4n |
| Special: as above, plus | |||||||
|
| hkl : h = 2n + 1 or h + k + l = 4n |
Symmetry of special projections
| Along [001] p2gg a' = 1/2a b' = 1/2b Origin at 0, 0, z | Along [100] c1m1 a' = 1/2b b' = 1/2c Origin at x, 0, 0 | Along [010] c11m a' = 1/2c b' = 1/2a Origin at 0, y, 0 |
Maximal non-isomorphic subgroups
| I | [2] F1d1 (Cc, 9) | (1; 3)+ | |
| [2] Fd11 (Cc, 9) | (1; 4)+ | ||
| [2] F112 (C2, 5) | (1; 2)+ |
| IIa | none |
| IIb | none |
Maximal isomorphic subgroups of lowest index
| IIc | [3] Fdd2 (a' = 3a or b' = 3b) (43); [3] Fdd2 (c' = 3c) (43) |
Minimal non-isomorphic supergroups
| I | [2] Fddd (70); [2] I41md (109); [2] I41cd (110); [2] I-42d (122) |
| II | [2] Pnn2 (a' = 1/2a, b' = 1/2b, c' = 1/2c) (34) |
