Ima2 C2v22 mm2 Orthorhombic No. 46 Ima2 Patterson symmetry Immm

Origin on n a 2

 Asymmetric unit 0 ≤ x ≤ 1/4; 0 ≤ y ≤ 1; 0 ≤ z ≤ 1/2

Symmetry operations

For (0, 0, 0)+ set

 (1)  1 (2)  2   0, 0, z (3)  a   x, 0, z (4)  m   1/4, y, z

For (1/21/21/2)+ set

 (1)  t(1/2, 1/2, 1/2) (2)  2(0, 0, 1/2)   1/4, 1/4, z (3)  c   x, 1/4, z (4)  n(0, 1/2, 1/2)   0, y, z

Generators selected (1); t(1, 0, 0); t(0, 1, 0); t(0, 0, 1); t(1/21/21/2); (2); (3)

Positions

Multiplicity, Wyckoff letter,
Site symmetry
Coordinates Reflection conditions
(0, 0, 0)+  (1/21/21/2)+  General:
 8 c 1
 (1) x, y, z (2) -x, -y, z (3) x + 1/2, -y, z (4) -x + 1/2, y, z
hkl : h + k + l = 2n
0kl : k + l = 2n
h0l : hl = 2n
hk0 : h + k = 2n
h00 : h = 2n
0k0 : k = 2n
00l : l = 2n
Special: as above, plus
 4 b m . .
 1/4, y, z 3/4, -y, z
no extra conditions
 4 a . . 2
 0, 0, z 1/2, 0, z
hkl : h = 2n

Symmetry of special projections

 Along [001]   c2mma' = a   b' = b   Origin at 1/4, 1/4, z Along [100]   c1m1a' = b   b' = c   Origin at x, 0, 0 Along [010]   p11ma' = 1/2c   b' = 1/2a   Origin at 0, y, 0

Maximal non-isomorphic subgroups

 I [2] I1a1 (Cc, 9) (1; 3)+ [2] Im11 (Cm, 8) (1; 4)+ [2] I112 (C2, 5) (1; 2)+
 IIa [2] Pna21 (33) 1; 3; (2; 4) + (1/2, 1/2, 1/2) [2] Pnc2 (30) 1; 2; (3; 4) + (1/2, 1/2, 1/2) [2] Pma2 (28) 1; 2; 3; 4 [2] Pmc21 (26) 1; 4; (2; 3) + (1/2, 1/2, 1/2)
 IIb none

Maximal isomorphic subgroups of lowest index

 IIc [3] Ima2 (a' = 3a) (46); [3] Ima2 (b' = 3b) (46); [3] Ima2 (c' = 3c) (46)

Minimal non-isomorphic supergroups

 I [2] Ibam (72); [2] Imma (74)
 II [2] Cmm2 (c' = 1/2c) (35); [2] Amm2 (a' = 1/2a) (38); [2] Bme2 (b' = 1/2b) (Aem2, 39)