Origin at centre (2/m) at 2/m n 1
| Asymmetric unit | 0 ≤ x ≤ 1/4; 0 ≤ y ≤ 1/2; 0 ≤ z ≤ 1/2 |
For (0, 0, 0)+ set
| (1) 1 | (2) 2(0, 0, 1/2) 0, 1/4, z | (3) 2(0, 1/2, 0) 0, y, 1/4 | (4) 2 x, 0, 0 |
| (5) -1 0, 0, 0 | (6) b x, y, 1/4 | (7) c x, 1/4, z | (8) m 0, y, z |
For (1/2, 1/2, 0)+ set
| (1) t(1/2, 1/2, 0) | (2) 2(0, 0, 1/2) 1/4, 0, z | (3) 2 1/4, y, 1/4 | (4) 2(1/2, 0, 0) x, 1/4, 0 |
| (5) -1 1/4, 1/4, 0 | (6) a x, y, 1/4 | (7) n(1/2, 0, 1/2) x, 0, z | (8) b 1/4, y, z |
Generators selected (1); t(1, 0, 0); t(0, 1, 0); t(0, 0, 1); t(1/2, 1/2, 0); (2); (3); (5)
Multiplicity, Wyckoff letter,
Site symmetry | Coordinates | Reflection conditions |
| | (0, 0, 0)+ (1/2, 1/2, 0)+ | General:
|
| | (1) x, y, z | (2) -x, -y + 1/2, z + 1/2 | (3) -x, y + 1/2, -z + 1/2 | (4) x, -y, -z | | (5) -x, -y, -z | (6) x, y + 1/2, -z + 1/2 | (7) x, -y + 1/2, z + 1/2 | (8) -x, y, z |
| hkl : h + k = 2n
0kl : k = 2n
h0l : h, l = 2n
hk0 : h, k = 2n
h00 : h = 2n
0k0 : k = 2n
00l : l = 2n
|
| | | Special: as above, plus
|
| | 0, y, z | 0, -y + 1/2, z + 1/2 | 0, y + 1/2, -z + 1/2 | 0, -y, -z |
| no extra conditions |
| | 1/4, y, 1/4 | 3/4, -y + 1/2, 3/4 | 3/4, -y, 3/4 | 1/4, y + 1/2, 1/4 |
| hkl : h = 2n
|
| | x, 0, 0 | -x, 1/2, 1/2 | -x, 0, 0 | x, 1/2, 1/2 |
| hkl : k + l = 2n
|
| | 1/4, 1/4, 0 | 3/4, 1/4, 1/2 | 3/4, 3/4, 1/2 | 1/4, 3/4, 0 |
| hkl : k, l = 2n
|
| | hkl : k + l = 2n
|
| | hkl : k + l = 2n
|
Symmetry of special projections
Along [001] p2mm
a' = 1/2a b' = 1/2b
Origin at 0, 0, z | Along [100] p2gm
a' = 1/2b b' = c
Origin at x, 0, 0 | Along [010] p2mm
a' = 1/2c b' = 1/2a
Origin at 0, y, 0 |
Maximal non-isomorphic subgroups
| I | | [2] C2ce (Aea2, 41) | (1; 4; 6; 7)+ |
| | | [2] Cm2e (Aem2, 39) | (1; 3; 6; 8)+ |
| | | [2] Cmc21 (36) | (1; 2; 7; 8)+ |
| | | [2] C2221 (20) | (1; 2; 3; 4)+ |
| | | [2] C12/c1 (C2/c, 15) | (1; 3; 5; 7)+ |
| | | [2] C1121/e (P21/c, 14) | (1; 2; 5; 6)+ |
| | | [2] C2/m11 (C2/m, 12) | (1; 4; 5; 8)+ |
| IIa | | [2] Pmnb (Pnma, 62) | 1; 3; 6; 8; (2; 4; 5; 7) + (1/2, 1/2, 0) |
| | | [2] Pbca (61) | 1; 3; 5; 7; (2; 4; 6; 8) + (1/2, 1/2, 0) |
| | | [2] Pbna (Pbcn, 60) | 1; 2; 3; 4; (5; 6; 7; 8) + (1/2, 1/2, 0) |
| | | [2] Pmca (Pbcm, 57) | 1; 2; 7; 8; (3; 4; 5; 6) + (1/2, 1/2, 0) |
| | | [2] Pbnb (Pccn, 56) | 1; 2; 5; 6; (3; 4; 7; 8) + (1/2, 1/2, 0) |
| | | [2] Pmcb (Pbam, 55) | 1; 2; 3; 4; 5; 6; 7; 8 |
| | | [2] Pbcb (Pcca, 54) | 1; 4; 6; 7; (2; 3; 5; 8) + (1/2, 1/2, 0) |
| | | [2] Pmna (53) | 1; 4; 5; 8; (2; 3; 6; 7) + (1/2, 1/2, 0) |
Maximal isomorphic subgroups of lowest index
| IIc | [3] Cmce (a' = 3a) (64); [3] Cmce (b' = 3b) (64); [3] Cmce (c' = 3c) (64) |
Minimal non-isomorphic supergroups
| II | [2] Fmmm (69); [2] Pmcm (a' = 1/2a, b' = 1/2b) (Pmma, 51); [2] Cmme (c' = 1/2c) (67) |
