| Ama2 | C2v16 | mm2 | Orthorhombic  |
| No. 40 | Ama2 | Patterson symmetry Ammm (Cmmm) | |
Origin on 1 a 2
| Asymmetric unit | 0 ≤ x ≤ 1/4; 0 ≤ y ≤ 1/2; 0 ≤ z ≤ 1 |
Symmetry operations
For (0, 0, 0)+ set
| (1) 1 | (2) 2 0, 0, z | (3) a x, 0, z | (4) m 1/4, 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) n(1/2, 0, 1/2) x, 1/4, z | (4) n(0, 1/2, 1/2) 1/4, y, z |
Generators selected (1); t(1, 0, 0); t(0, 1, 0); t(0, 0, 1); t(0, 1/2, 1/2); (2); (3)
Positions
| Multiplicity, Wyckoff letter, Site symmetry | Coordinates | Reflection conditions | |||||||
| (0, 0, 0)+ (0, 1/2, 1/2)+ | General: | ||||||||
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| hkl : k + l = 2n 0kl : k + l = 2n h0l : h, l = 2n hk0 : k = 2n h00 : h = 2n 0k0 : k = 2n 00l : l = 2n |
| Special: as above, plus | |||||||
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| no extra conditions | |||||
|
| hkl : h = 2n |
Symmetry of special projections
| Along [001] p2mg a' = a b' = 1/2b Origin at 0, 0, z | Along [100] c1m1 a' = b b' = c Origin at x, 0, 0 | Along [010] p11m a' = 1/2c b' = 1/2a Origin at 0, y, 0 |
Maximal non-isomorphic subgroups
| I | [2] A1a1 (Cc, 9) | (1; 3)+ | |
| [2] Am11 (Pm, 6) | (1; 4)+ | ||
| [2] A112 (C2, 5) | (1; 2)+ |
| IIa | [2] Pnn2 (34) | 1; 2; (3; 4) + (0, 1/2, 1/2) | |
| [2] Pna21 (33) | 1; 3; (2; 4) + (0, 1/2, 1/2) | ||
| [2] Pmn21 (31) | 1; 4; (2; 3) + (0, 1/2, 1/2) | ||
| [2] Pma2 (28) | 1; 2; 3; 4 |
| IIb | none |
Maximal isomorphic subgroups of lowest index
| IIc | [3] Ama2 (a' = 3a) (40); [3] Ama2 (b' = 3b) (40); [3] Ama2 (c' = 3c) (40) |
Minimal non-isomorphic supergroups
| I | [2] Cmcm (63); [2] Cccm (66); [3] P-6c2 (188); [3] P-62c (190) |
| II | [2] Fmm2 (42); [2] Pma2 (b' = 1/2b, c' = 1/2c) (28); [2] Amm2 (a' = 1/2a) (38) |
