pma2 mm2 Orthorhombic/Rectangular
No. 24 pma2 Patterson symmetry pmmm

symmetry group diagram

Origin on 1a2

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

Symmetry operations

(1)  1
      (1 | 0, 0, 0)
(2)  2   0, 0, z
      (2z | 0, 0, 0)
(3)  a   x, 0, z
      (my | 1/2, 0, 0)
(4)  m   1/4yz
      (mx | 1/2, 0, 0)

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

Positions

Multiplicity, Wyckoff letter,
Site symmetry
Coordinates Reflection conditions

  General:
4 d 1
(1) xyz (2) -x-yz (3) x + 1/2-yz (4) -x + 1/2yz
h0: h = 2n
    Special: as above, plus
2 c  m . . 
1/4yz 3/4-yz
no extra conditions
2 b  . . 2 
0, 1/2z 1/21/2z
hk: h = 2n
2 a  . . 2 
0, 0, z 1/2, 0, z
hk: h = 2n

Symmetry of special projections

Along [001]   p2mg
a' = a   b' = b   
Origin at 0, 0, z
Along [100]   [script p]1m1
a' = b   
Origin at x, 0, 0
Along [010]   [script p]1m1
a' = 1/2a   
Origin at 0, y, 0

Maximal non-isotypic subgroups


I [2] p1a1 (pb11, 12) 1; 3
  [2] pm11 (11) 1; 4
  [2] p112 (3) 1; 2
IIa none
IIb [2] pba2 (b' = 2b) (25)

Maximal isotypic subgroups of lowest index


IIc [2] pma2 (b' = 2b) (24); [3] pma2 (a' = 3a) (24)

Minimal non-isotypic supergroups


I [2] pmaa (38); [2] pmam (40); [2] pman (42); [2] pbma (45)
II [2] cmm2 (26); [2] pmm2 (a' = 1/2a) (23)








































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