Pma2 C2v4 mm2 Orthorhombic No. 28 Pma2 Patterson symmetry Pmmm

Origin on 1 a 2

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

Symmetry operations

 (1)  1 (2)  2   0, 0, z (3)  a   x, 0, z (4)  m   1/4, 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 d 1
 (1) x, y, z (2) -x, -y, z (3) x + 1/2, -y, z (4) -x + 1/2, y, z
h0l : h = 2n
h00 : h = 2n
Special: as above, plus
 2 c m . .
 1/4, y, z 3/4, -y, z
no extra conditions
 2 b . . 2
 0, 1/2, z 1/2, 1/2, z
hkl : h = 2n
 2 a . . 2
 0, 0, z 1/2, 0, z
hkl : h = 2n

Symmetry of special projections

 Along [001]   p2mga' = a   b' = b   Origin at 0, 0, z Along [100]   p1m1a' = b   b' = c   Origin at x, 0, 0 Along [010]   p11ma' = c   b' = 1/2a   Origin at 0, y, 0

Maximal non-isomorphic subgroups

 I [2] P1a1 (Pc, 7) 1; 3 [2] Pm11 (Pm, 6) 1; 4 [2] P112 (P2, 3) 1; 2
 IIa none
 IIb [2] Pba2 (b' = 2b) (32); [2] Pmn21 (c' = 2c) (31); [2] Pcn2 (c' = 2c) (Pnc2, 30); [2] Pca21 (c' = 2c) (29); [2] Aea2 (b' = 2b, c' = 2c) (41); [2] Ama2 (b' = 2b, c' = 2c) (40)

Maximal isomorphic subgroups of lowest index

 IIc [2] Pma2 (b' = 2b) (28); [2] Pma2 (c' = 2c) (28); [3] Pma2 (a' = 3a) (28)

Minimal non-isomorphic supergroups

 I [2] Pccm (49); [2] Pmma (51); [2] Pmna (53); [2] Pbcm (57)
 II [2] Cmm2 (35); [2] Bme2 (Aem2, 39); [2] Ama2 (40); [2] Ima2 (46); [2] Pmm2 (a' = 1/2a) (25)