Pmc21 C2v2 mm2 Orthorhombic No. 26 Pmc21 Patterson symmetry Pmmm

Origin on m c 21

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

Symmetry operations

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

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

Positions

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

Symmetry of special projections

 Along [001]   p2mma' = a   b' = b   Origin at 0, 0, z Along [100]   p1g1a' = b   b' = c   Origin at x, 0, 0 Along [010]   p11ma' = 1/2c   b' = a   Origin at 0, y, 0

Maximal non-isomorphic subgroups

 I [2] P1c1 (Pc, 7) 1; 3 [2] Pm11 (Pm, 6) 1; 4 [2] P1121 (P21, 4) 1; 2
 IIa none
 IIb [2] Pmn21 (a' = 2a) (31); [2] Pbc21 (b' = 2b) (Pca21, 29); [2] Cmc21 (a' = 2a, b' = 2b) (36)

Maximal isomorphic subgroups of lowest index

 IIc [2] Pmc21 (a' = 2a) (26); [2] Pmc21 (b' = 2b) (26); [3] Pmc21 (c' = 3c) (26)

Minimal non-isomorphic supergroups

 I [2] Pmma (51); [2] Pbam (55); [2] Pbcm (57); [2] Pnma (62)
 II [2] Cmc21 (36); [2] Amm2 (38); [2] Bme2 (Aem2, 39); [2] Ima2 (46); [2] Pmm2 (c' = 1/2c) (25)