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

Origin at centre (2/m)

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

Symmetry operations

For (0, 0, 0)+ set

 (1)  1 (2)  2   x, 0, 0 (3)  -1   0, 0, 0 (4)  m   0, y, z

For (1/21/2, 0)+ set

 (1)  t(1/2, 1/2, 0) (2)  2(1/2, 0, 0)   x, 1/4, 0 (3)  -1   1/4, 1/4, 0 (4)  b   1/4, y, z

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) x, y, z (2) x, -y, -z (3) -x, -y, -z (4) -x, y, z
hk: h + k = 2n
h0: h = 2n
0k: k = 2n
Special: as above, plus
 4 e m
 0, y, z 0, -y, -z
no extra conditions
 4 d 2
 x, 0, 0 -x, 0, 0
no extra conditions
 4 c -1
 1/4, 1/4, 0 1/4, 3/4, 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]   211 a' = 1/2b    Origin at x, 0, 0 Along [010]   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) + (1/2, 1/2, 0) [2] p2/b11 (16) 1; 2; (3; 4) + (1/2, 1/2, 0) [2] p21/m11 (15) 1; 4; (2; 3) + (1/2, 1/2, 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' = 1/2a, b' = 1/2b) (14)