p6mm 6mm Hexagonal/Hexagonal
No. 77 p6mm Patterson symmetry p6/mmm

symmetry group diagram

Origin on 6mm

Asymmetric unit 0 ≤ x ≤ 2/3; 0 ≤ y ≤ 1/3; x ≤ (1 + y)/2; y ≤ x/2
Vertices
0, 0   1/2, 0   2/31/3  

Symmetry operations

(1)  1    (2)  3+   0, 0, z (3)  3-   0, 0, z
(4)  2   0, 0, z (5)  6-   0, 0, z (6)  6+   0, 0, z
(7)  m   x-xz (8)  m   x, 2xz (9)  m   2xxz
(10)  m   xxz (11)  m   x, 0, z (12)  m   0, yz

Generators selected (1); t(1, 0, 0); t(0, 1, 0); (2); (4); (7)

Positions

Multiplicity, Wyckoff letter,
Site symmetry
Coordinates Reflection conditions

  General:
12 f 1
(1) xyz (2) -yx - yz (3) -x + y-xz
(4) -x-yz (5) y-x + yz (6) x - yxz
(7) -y-xz (8) -x + yyz (9) xx - yz
(10) yxz (11) x - y-yz (12) -x-x + yz
no conditions
    Special: no extra conditions
6 e  . m . 
x-xz x, 2xz -(2x), -xz -xxz -x, -(2x), z 2xxz
6 d  . . m 
x, 0, z 0, xz -x-xz -x, 0, z 0, -xz xxz
3 c  2 m m 
1/2, 0, z 0, 1/2z 1/21/2z
2 b  3 m . 
1/32/3z 2/31/3z
1 a  6 m m 
0, 0, z

Symmetry of special projections

Along [001]   p6mm
a' = a   b' = b   
Origin at 0, 0, z
Along [100]   [script p]1m1
a' = 1/2(a + 2b)   
Origin at x, 0, 0
Along [210]   [script p]1m1
a' = 1/2b   
Origin at x1/2x, 0

Maximal non-isotypic subgroups


I [2] p611 (p6, 73) 1; 2; 3; 4; 5; 6
  [2] p31m (70) 1; 2; 3; 10; 11; 12
  [2] p3m1 (69) 1; 2; 3; 7; 8; 9
  [3] p2mm (cmm2, 26) 1; 4; 7; 10
  [3] p2mm (cmm2, 26) 1; 4; 8; 11
  [3] p2mm (cmm2, 26) 1; 4; 9; 12
IIa none
IIb none

Maximal isotypic subgroups of lowest index


IIc [3] h6mm (a' = 3ab' = 3b) (p6mm, 77)

Minimal non-isotypic supergroups


I [2] p6/mmm (80)
II none








































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