Pmm2 C2v1 mm2 Orthorhombic No. 25 Pmm2 Patterson symmetry Pmmm

Origin on m m 2

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

Symmetry operations

 (1)  1 (2)  2   0, 0, z (3)  m   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 i 1
 (1) x, y, z (2) -x, -y, z (3) x, -y, z (4) -x, y, z
no conditions
Special: as above, plus
 2 h m . .
 1/2, y, z 1/2, -y, z
no extra conditions
 2 g m . .
 0, y, z 0, -y, z
no extra conditions
 2 f . m .
 x, 1/2, z -x, 1/2, z
no extra conditions
 2 e . m .
 x, 0, z -x, 0, z
no extra conditions
 1 d m m 2
 1/2, 1/2, z
no extra conditions
 1 c m m 2
 1/2, 0, z
no extra conditions
 1 b m m 2
 0, 1/2, z
no extra conditions
 1 a m m 2
 0, 0, z
no extra conditions

Symmetry of special projections

 Along [001]   p2mma' = a   b' = b   Origin at 0, 0, z Along [100]   p1m1a' = b   b' = c   Origin at x, 0, 0 Along [010]   p11ma' = c   b' = a   Origin at 0, y, 0

Maximal non-isomorphic subgroups

 I [2] P1m1 (Pm, 6) 1; 3 [2] Pm11 (Pm, 6) 1; 4 [2] P112 (P2, 3) 1; 2
 IIa none
 IIb [2] Pma2 (a' = 2a) (28); [2] Pbm2 (b' = 2b) (Pma2, 28); [2] Pcc2 (c' = 2c) (27); [2] Pmc21 (c' = 2c) (26); [2] Pcm21 (c' = 2c) (Pmc21, 26); [2] Aem2 (b' = 2b, c' = 2c) (39); [2] Amm2 (b' = 2b, c' = 2c) (38); [2] Bme2 (a' = 2a, c' = 2c) (Aem2, 39); [2] Bmm2 (a' = 2a, c' = 2c) (Amm2, 38); [2] Cmm2 (a' = 2a, b' = 2b) (35); [2] Fmm2 (a' = 2a, b' = 2b, c' = 2c) (42)

Maximal isomorphic subgroups of lowest index

 IIc [2] Pmm2 (a' = 2a or b' = 2b) (25); [2] Pmm2 (c' = 2c) (25)

Minimal non-isomorphic supergroups

 I [2] Pmmm (47); [2] Pmma (51); [2] Pmmn (59); [2] P4mm (99); [2] P42mc (105); [2] P-4m2 (115)
 II [2] Cmm2 (35); [2] Amm2 (38); [2] Bmm2 (Amm2, 38); [2] Imm2 (44)