| Pbca | D2h15 | mmm | Orthorhombic  |
| No. 61 | P21/b21/c21/a | Patterson symmetry Pmmm | |
Origin at -1
| Asymmetric unit | 0 ≤ x ≤ 1/2; 0 ≤ y ≤ 1/2; 0 ≤ z ≤ 1/2 |
Symmetry operations
| (1) 1 | (2) 2(0, 0, 1/2) 1/4, 0, z | (3) 2(0, 1/2, 0) 0, y, 1/4 | (4) 2(1/2, 0, 0) x, 1/4, 0 |
| (5) -1 0, 0, 0 | (6) a x, y, 1/4 | (7) c x, 1/4, z | (8) b 1/4, y, z |
Generators selected (1); t(1, 0, 0); t(0, 1, 0); t(0, 0, 1); (2); (3); (5)
Positions
| Multiplicity, Wyckoff letter, Site symmetry | Coordinates | Reflection conditions | |||||||||||
| General: | |||||||||||||
|
| 0kl : k = 2n h0l : l = 2n hk0 : h = 2n h00 : h = 2n 0k0 : k = 2n 00l : l = 2n |
| Special: as above, plus | |||||||||
|
| hkl : h + k, h + l, k + l = 2n | |||||||
|
| hkl : h + k, h + l, k + l = 2n |
Symmetry of special projections
| Along [001] p2gm a' = 1/2a b' = b Origin at 0, 0, z | Along [100] p2gm a' = 1/2b b' = c Origin at x, 0, 0 | Along [010] p2gm a' = 1/2c b' = a Origin at 0, y, 0 |
Maximal non-isomorphic subgroups
| I | [2] Pbc21 (Pca21, 29) | 1; 2; 7; 8 | |
| [2] Pb21a (Pca21, 29) | 1; 3; 6; 8 | ||
| [2] P21ca (Pca21, 29) | 1; 4; 6; 7 | ||
| [2] P212121 (19) | 1; 2; 3; 4 | ||
| [2] P1121/a (P21/c, 14) | 1; 2; 5; 6 | ||
| [2] P121/c1 (P21/c, 14) | 1; 3; 5; 7 | ||
| [2] P21/b11 (P21/c, 14) | 1; 4; 5; 8 |
| IIa | none |
| IIb | none |
Maximal isomorphic subgroups of lowest index
| IIc | [3] Pbca (a' = 3a or b' = 3b or c' = 3c) (61) |
Minimal non-isomorphic supergroups
| I | [3] Pa-3 (205) |
| II | [2] Aema (Cmce, 64); [2] Bbem (Cmce, 64); [2] Cmce (64); [2] Ibca (73); [2] Pbcm (a' = 1/2a) (57); [2] Pmca (b' = 1/2b) (Pbcm, 57); [2] Pbma (c' = 1/2c) (Pbcm, 57) |
