| Pca21 | C2v5 | mm2 | Orthorhombic  |
| No. 29 | Pca21 | Patterson symmetry Pmmm | |
Origin on 1 a 21
| Asymmetric unit | 0 ≤ x ≤ 1/4; 0 ≤ y ≤ 1; 0 ≤ z ≤ 1 |
Symmetry operations
| (1) 1 | (2) 2(0, 0, 1/2) 0, 0, z | (3) a x, 0, z | (4) c 1/4, y, z |
Generators selected (1); t(1, 0, 0); t(0, 1, 0); t(0, 0, 1); (2); (3)
Positions
| Multiplicity, Wyckoff letter, Site symmetry | Coordinates | Reflection conditions | |||||||
| General: | |||||||||
|
| 0kl : l = 2n h0l : h = 2n h00 : h = 2n 00l : l = 2n |
Symmetry of special projections
| Along [001] p2mg a' = a b' = b Origin at 0, 0, z | Along [100] p1m1 a' = b b' = 1/2c Origin at x, 0, 0 | Along [010] p11g a' = c b' = 1/2a Origin at 0, y, 0 |
Maximal non-isomorphic subgroups
| I | [2] P1a1 (Pc, 7) | 1; 3 | |
| [2] Pc11 (Pc, 7) | 1; 4 | ||
| [2] P1121 (P21, 4) | 1; 2 |
| IIa | none |
| IIb | [2] Pna21 (b' = 2b) (33) |
Maximal isomorphic subgroups of lowest index
| IIc | [2] Pca21 (b' = 2b) (29); [3] Pca21 (a' = 3a) (29); [3] Pca21 (c' = 3c) (29) |
Minimal non-isomorphic supergroups
| I | [2] Pcca (54); [2] Pbcm (57); [2] Pbcn (60); [2] Pbca (61) |
| II | [2] Ccm21 (Cmc21, 36); [2] Bme2 (Aem2, 39); [2] Aea2 (41); [2] Iba2 (45); [2] Pcm21 (a' = 1/2a) (Pmc21, 26); [2] Pma2 (c' = 1/2c) (28) |
