R-3 C3i2 -3 Trigonal info
No. 148 R-3 Patterson symmetry R-3
RHOMBOHEDRAL AXES

symmetry group diagram

Origin at centre (-3)

Asymmetric unit 0 ≤ x ≤ 1; 0 ≤ y ≤ 1; 0 ≤ z ≤ 1/2; z ≤ min(xy, 1 - x, 1 - y)
Vertices
0, 0, 0  1, 0, 0  1, 1, 0  0, 1, 0  1/21/21/2  

Symmetry operations

(1)  1   (2)  3+   xxx(3)  3-   xxx
(4)  -1   0, 0, 0(5)  -3+   xxx; 0, 0, 0(6)  -3-   xxx; 0, 0, 0

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 f 1
(1) xyz(2) zxy(3) yzx
(4) -x-y-z(5) -z-x-y(6) -y-z-x
no conditions
    Special: as above, plus
3 e  -1 
0, 1/21/2 1/2, 0, 1/2 1/21/2, 0
no extra conditions
3 d  -1 
1/2, 0, 0 0, 1/2, 0 0, 0, 1/2
no extra conditions
2 c  3 . 
xxx -x-x-x
no extra conditions
1 b  -3 . 
1/21/21/2
no extra conditions
1 a  -3 . 
0, 0, 0
no extra conditions

Symmetry of special projections

Along [111]   p6
a' = 1/3(2a - b - c)   b' = 1/3(-a + 2b - c)   
Origin at xxx
Along [1-10]   p2
a' = 1/2(a + b - 2c)   b' = c   
Origin at x-x, 0
Along [2-1-1]   p2
a' = 1/2(b - c)   b' = 1/3(a + b + c)   
Origin at 2x-x-x

Maximal non-isomorphic subgroups

I [2] R3 (146)1; 2; 3
  [3] R-1 (P-1, 2)1; 4
IIa none
IIb[3] P-3 (a' = a - bb' = b - cc' = a + b + c) (147)

Maximal isomorphic subgroups of lowest index

IIc[2] R-3 (a' = b + cb' = a + cc' = a + b) (148); [4] R-3 (a' = -a + b + cb' = a - b + cc' = a + b - c) (148)

Minimal non-isomorphic supergroups

I[2] R-3m (166); [2] R-3c (167); [4] Pm-3 (200); [4] Pn-3 (201); [4] Fm-3 (202); [4] Fd-3 (203); [4] Im-3 (204); [4] Pa-3 (205); [4] Ia-3 (206)
II[3] P-3 (a' = 1/3(2a - b - c), b' = 1/3(-a + 2b - c), c' = 1/3(a + b + c)) (147)








































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