c2/m11 2/m Monoclinic/Rectangular
No. 18 c2/m11 Patterson symmetry c2/m11

symmetry group diagram

Origin at centre (2/m)

Asymmetric unit 0 ≤ x ≤ 1/4; 0 ≤ y ≤ 1/2

Symmetry operations

For (0, 0, 0)+ set

(1)  1
      (1 | 0, 0, 0)
(2)  2   x, 0, 0
      (2x | 0, 0, 0)
(3)  -1   0, 0, 0
      (-1 | 0, 0, 0)
(4)  m   0, yz
      (mx | 0, 0, 0)

For (1/21/2, 0)+ set

(1)  t (1/21/2, 0)  
      (1 | 1/21/2, 0)
(2)  2 (1/2, 0, 0)   x1/4, 0
      (2x | 1/21/2, 0)
(3)  -1   1/41/4, 0
      (-1 | 1/21/2, 0)
(4)  b   1/4yz
      (mx | 1/21/2, 0)

Generators selected (1); t(1, 0, 0); t(0, 1, 0); t(1/21/2, 0); (2); (3)

Positions

Multiplicity, Wyckoff letter,
Site symmetry
Coordinates Reflection conditions

  (0, 0, 0)+  (1/21/2, 0)+   General:
8 f 1
(1) xyz (2) x-y-z (3) -x-y-z (4) -xyz
hk: h + k = 2n
h0: h = 2n
0k: k = 2n
    Special: as above, plus
4 e  m 
0, yz 0, -y-z    
no extra conditions
4 d  2 
x, 0, 0 -x, 0, 0    
no extra conditions
4 c  -1 
1/41/4, 0 1/43/4, 0    
hk: k = 2n
2 b  2/m 
1/2, 0, 0  
no extra conditions
2 a  2/m 
0, 0, 0  
no extra conditions

Symmetry of special projections

Along [001]   c2mm
a' = a   b' = bp   
Origin at 0, 0, z
Along [100]   [script p]211
a' = 1/2b   
Origin at x, 0, 0
Along [010]   [script p]2mm
a' = 1/2a   
Origin at 0, y, 0

Maximal non-isotypic subgroups


I [2] cm11 (13) (1; 4)+
  [2] c211 (10) (1; 2)+
  [2] c-1 (p-1, 2) (1; 3)+
IIa [2] p21/b11 (17) 1; 3; (2; 4) + (1/21/2, 0)
  [2] p2/b11 (16) 1; 2; (3; 4) + (1/21/2, 0)
  [2] p21/m11 (15) 1; 4; (2; 3) + (1/21/2, 0)
  [2] p2/m11 (14) 1; 2; 3; 4
IIb none

Maximal isotypic subgroups of lowest index


IIc [3] c2/m11 (a' = 3a) (18)

Minimal non-isotypic supergroups


I [2] cmmm (47); [2] cmme (48); [3] p-31m (71); [3] p-3m1 (72)
II [2] p2/m11 (a' = 1/2ab' = 1/2b) (14)








































to end of page
to top of page