Origin on 2m m on 42c m
| Asymmetric unit | 0 ≤ x ≤ 1/2; 0 ≤ y ≤ 1/2; 0 ≤ z ≤ 1; x ≤ y |
| (1) 1 | (2) 2 0, 0, z | (3) 4+(0, 0, 1/2) 0, 0, z | (4) 4-(0, 0, 1/2) 0, 0, z |
| (5) c x, 0, z | (6) c 0, y, z | (7) m x, -x, z | (8) m x, x, z |
Generators selected (1); t(1, 0, 0); t(0, 1, 0); t(0, 0, 1); (2); (3); (5)
Multiplicity, Wyckoff letter,
Site symmetry | Coordinates | Reflection conditions |
| | | General:
|
| | (1) x, y, z | (2) -x, -y, z | (3) -y, x, z + 1/2 | (4) y, -x, z + 1/2 | | (5) x, -y, z + 1/2 | (6) -x, y, z + 1/2 | (7) -y, -x, z | (8) y, x, z |
| 0kl : l = 2n
00l : l = 2n
|
| | | Special: as above, plus
|
| | x, x, z | -x, -x, z | -x, x, z + 1/2 | x, -x, z + 1/2 |
| no extra conditions |
| | 0, 1/2, z | 1/2, 0, z + 1/2 | 0, 1/2, z + 1/2 | 1/2, 0, z |
| hkl : h + k, l = 2n
|
| | 1/2, 1/2, z | 1/2, 1/2, z + 1/2 |
| hkl : l = 2n
|
| | hkl : l = 2n
|
Symmetry of special projections
Along [001] p4mm
a' = a b' = b
Origin at 0, 0, z | Along [100] p1m1
a' = b b' = 1/2c
Origin at x, 0, 0 | Along [110] p1m1
a' = 1/2(-a + b) b' = c
Origin at x, x, 0 |
Maximal non-isomorphic subgroups
| I | | [2] P4211 (P42, 77) | 1; 2; 3; 4 |
| | | [2] P21m (Cmm2, 35) | 1; 2; 7; 8 |
| | | [2] P2c1 (Pcc2, 27) | 1; 2; 5; 6 |
| IIb | [2] C42cd (a' = 2a, b' = 2b) (P42bc, 106); [2] C42cm (a' = 2a, b' = 2b) (P42mc, 105) |
Maximal isomorphic subgroups of lowest index
| IIc | [3] P42cm (c' = 3c) (101); [9] P42cm (a' = 3a, b' = 3b) (101) |
Minimal non-isomorphic supergroups
| I | [2] P42/mcm (132); [2] P42/ncm (138) |
| II | [2] C42cm (P42mc, 105); [2] I4cm (108); [2] P4mm (c' = 1/2c) (99) |
