P31m C3v2 31m Trigonal info
No. 157 P31m Patterson symmetry P-31m

symmetry group diagram

Origin on 3 1 m

Asymmetric unit 0 ≤ x ≤ 2/3; 0 ≤ y ≤ 1/2; 0 ≤ z ≤ 1; x ≤ (y + 1)/2; y ≤ min(1 - xx)
Vertices
0, 0, 0  1/2, 0, 0  2/31/3, 0  1/21/2, 0  
0, 0, 1  1/2, 0, 1  2/31/3, 1  1/21/2, 1  

Symmetry operations

(1)  1   (2)  3+   0, 0, z(3)  3-   0, 0, z
(4)  m   xxz(5)  m   x, 0, z(6)  m   0, yz

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

Positions

Multiplicity, Wyckoff letter,
Site symmetry
Coordinates Reflection conditions
 General:
6 d 1
(1) xyz(2) -yx - yz(3) -x + y-xz
(4) yxz(5) x - y-yz(6) -x-x + yz
no conditions
    Special: as above, plus
3 c  . . m 
x, 0, z 0, xz -x-xz
no extra conditions
2 b  3 . . 
1/32/3z 2/31/3z
no extra conditions
1 a  3 . m 
0, 0, z
no extra conditions

Symmetry of special projections

Along [001]   p31m
a' = a   b' = b   
Origin at 0, 0, z
Along [100]   p1m1
a' = 1/2(a + 2b)   b' = c   
Origin at x, 0, 0
Along [210]   p1
a' = 1/2b   b' = c   
Origin at x1/2x, 0

Maximal non-isomorphic subgroups

I [2] P311 (P3, 143)1; 2; 3
 [brace][3] P11m (Cm, 8)1; 4
 [3] P11m (Cm, 8)1; 5
 [3] P11m (Cm, 8)1; 6
IIa none
IIb[2] P31c (c' = 2c) (159); [3] H31m (a' = 3ab' = 3b) (P3m1, 156); [3] R3m (a' = a - bb' = a + 2bc' = 3c) (160); [3] R3m (a' = 2a + bb' = -a + bc' = 3c) (160)

Maximal isomorphic subgroups of lowest index

IIc[2] P31m (c' = 2c) (157); [4] P31m (a' = 2ab' = 2b) (157)

Minimal non-isomorphic supergroups

I[2] P-31m (162); [2] P6mm (183); [2] P63cm (185); [2] P-62m (189)
II[3] H31m (P3m1, 156)








































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