p2mm 2mm Rectangularinfo
No. 6 p2mm Patterson symmetry p2mm

symmetry group diagram

Origin at 2 m m

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

Symmetry operations

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

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

Positions

Multiplicity, Wyckoff letter,
Site symmetry		 Coordinates Reflection conditions
 General:
4 i 1
(1) x, y(2) -x, -y(3) -x, y(4) x, -y
no conditions
    Special: as above, plus
2 h  . m . 
1/2, y 1/2, -y
no extra conditions
2 g  . m . 
0, y 0, -y
no extra conditions
2 f  . . m 
x, 1/2 -x, 1/2
no extra conditions
2 e  . . m 
x, 0 -x, 0
no extra conditions
1 d  2 m m 
1/2, 1/2
no extra conditions
1 c  2 m m 
1/2, 0
no extra conditions
1 b  2 m m 
0, 1/2
no extra conditions
1 a  2 m m 
0, 0
no extra conditions

Maximal non-isomorphic subgroups

I[2] p1m1 (pm, 3)1; 3
 [2] p11m (pm, 3)1; 4
 [2] p211 (p2, 2)1; 2
IIa none
IIb[2] p2mg (a' = 2a) (7); [2] p2gm (b' = 2b) (p2mg, 7); [2] c2mm (a' = 2a, b' = 2b) (9)

Maximal isomorphic subgroups of lowest index

IIc[2] p2mm (a' = 2a or b' = 2b) (6)

Minimal non-isomorphic supergroups

I[2] p4mm (11)
II[2] c2mm (9)








































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