pba2 mm2 Orthorhombic/Rectangular
No. 25 pba2 Patterson symmetry pmmm

symmetry group diagram

Origin on 112

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

Symmetry operations

(1)  1
      (1 | 0, 0, 0)
(2)  2   0, 0, z
      (2z | 0, 0, 0)
(3)  a   x1/4z
      (my | 1/21/2, 0)
(4)  b   1/4yz
      (mx | 1/21/2, 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 c 1
(1) xyz (2) -x-yz (3) x + 1/2-y + 1/2z (4) -x + 1/2y + 1/2z
h0: h = 2n
0k: k = 2n
    Special: as above, plus
2 b  . . 2 
0, 1/2z 1/2, 0, z
hk: h + k = 2n
2 a  . . 2 
0, 0, z 1/21/2z
hk: h + k = 2n

Symmetry of special projections

Along [001]   p2gg
a' = a   b' = b   
Origin at 0, 0, z
Along [100]   [script p]1m1
a' = 1/2b   
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] pb11 (12) 1; 4
  [2] p112 (3) 1; 2
IIa none
IIb none

Maximal isotypic subgroups of lowest index


IIc [3] pba2 (a' = 3a or b' = 3b) (25)

Minimal non-isotypic supergroups


I [2] pban (39); [2] pbaa (43); [2] pbam (44); [2] p4bm (56); [2] p-4b2 (60)
II [2] cmm2 (26); [2] pma2 (b' = 1/2b) (24)








































to end of page
to top of page