| Pnna | D2h6 | mmm | Orthorhombic  |
| No. 52 | P2/n21/n2/a | Patterson symmetry Pmmm | |
Origin at -1 on n 1 a
| Asymmetric unit | 0 ≤ x ≤ 1; 0 ≤ y ≤ 1/4; 0 ≤ z ≤ 1/2 |
Symmetry operations
| (1) 1 | (2) 2 1/4, 0, z | (3) 2(0, 1/2, 0) 1/4, y, 1/4 | (4) 2 x, 1/4, 1/4 |
| (5) -1 0, 0, 0 | (6) a x, y, 0 | (7) n(1/2, 0, 1/2) x, 1/4, z | (8) n(0, 1/2, 1/2) 0, 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: | |||||||||||||
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| 0kl : k + l = 2n h0l : h + l = 2n hk0 : h = 2n h00 : h = 2n 0k0 : k = 2n 00l : l = 2n |
| Special: as above, plus | |||||||||
|
| hkl : h + l = 2n | |||||||
|
| hkl : h + k + l = 2n | |||||||
|
| hkl : h, k + l = 2n | |||||||
|
| hkl : h, k + l = 2n |
Symmetry of special projections
| Along [001] p2gm a' = 1/2a b' = b Origin at 0, 0, z | Along [100] c2mm a' = b b' = c Origin at x, 0, 0 | Along [010] c2mm a' = c b' = a Origin at 1/4, y, 1/4 |
Maximal non-isomorphic subgroups
| I | [2] Pnn2 (34) | 1; 2; 7; 8 | |
| [2] Pn21a (Pna21, 33) | 1; 3; 6; 8 | ||
| [2] P2na (Pnc2, 30) | 1; 4; 6; 7 | ||
| [2] P2212 (P2221, 17) | 1; 2; 3; 4 | ||
| [2] P121/n1 (P21/c, 14) | 1; 3; 5; 7 | ||
| [2] P112/a (P2/c, 13) | 1; 2; 5; 6 | ||
| [2] P2/n11 (P2/c, 13) | 1; 4; 5; 8 |
| IIa | none |
| IIb | none |
Maximal isomorphic subgroups of lowest index
| IIc | [3] Pnna (a' = 3a) (52); [3] Pnna (b' = 3b) (52); [3] Pnna (c' = 3c) (52) |
Minimal non-isomorphic supergroups
| I | none |
| II | [2] Bbmm (Cmcm, 63); [2] Amaa (Cccm, 66); [2] Ccce (68); [2] Imma (74); [2] Pncm (a' = 1/2a) (Pmna, 53); [2] Pcna (b' = 1/2b) (Pban, 50); [2] Pbaa (c' = 1/2c) (Pcca, 54) |
