Move your mouse over or click on the links to get information about each item. Detailed information on the space-group tables is given in Chapter 2.2.

Space-group diagrams: projections of the symmetry elements and a diagram showing a set of equivalent points in the general position

Origin on m m 2

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

For (0, 0, 0)+ set

(1)  1   (2)  2   0, 0, z(3)  m   x, 0, z(4)  m   0, yz

For (1/21/2, 0)+ set

(1)  t(1/21/2, 0)   (2)  2   1/41/4z(3)  a   x1/4z(4)  b   1/4yz

Generators selected (1); t(1, 0, 0); t(0, 1, 0); t(0, 0, 1); 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) xyz(2) -x-yz(3) x-yz(4) -xyz
hkl : h + k = 2n
0kl : k = 2n
h0l : h = 2n
hk0 : h + k = 2n
h00 : h = 2n
0k0 : k = 2n
    Special: as above, plus
4 e  m . . 
0, yz 0, -yz
no extra conditions
4 d  . m . 
x, 0, z -x, 0, z
no extra conditions
4 c  . . 2 
1/41/4z 1/43/4z
hkl : h = 2n
2 b  m m 2 
0, 1/2z
no extra conditions
2 a  m m 2 
0, 0, z
no extra conditions

Symmetry of special projections

Along [001]   c2mm
a' = a   b' = b   
Origin at 0, 0, z
Along [100]   p1m1
a' = 1/2b   b' = c   
Origin at x, 0, 0
Along [010]   p11m
a' = c   b' = 1/2a   
Origin at 0, y, 0

Maximal non-isomorphic subgroups

I [2] C1m1 (Cm, 8)(1; 3)+
  [2] Cm11 (Cm, 8)(1; 4)+
  [2] C112 (P2, 3)(1; 2)+
IIa [2] Pba2 (32)1; 2; (3; 4) + (1/21/2, 0)
  [2] Pbm2 (Pma2, 28)1; 3; (2; 4) + (1/21/2, 0)
  [2] Pma2 (28)1; 4; (2; 3) + (1/21/2, 0)
  [2] Pmm2 (25)1; 2; 3; 4
IIb[2] Ima2 (c' = 2c) (46); [2] Ibm2 (c' = 2c) (Ima2, 46); [2] Iba2 (c' = 2c) (45); [2] Imm2 (c' = 2c) (44); [2] Ccc2 (c' = 2c) (37); [2] Cmc21 (c' = 2c) (36); [2] Ccm21 (c' = 2c) (Cmc21, 36)

Maximal isomorphic subgroups of lowest index

IIc[2] Cmm2 (c' = 2c) (35); [3] Cmm2 (a' = 3a or b' = 3b) (35)

Minimal non-isomorphic supergroups

I[2] Cmmm (65); [2] Cmme (67); [2] P4mm (99); [2] P4bm (100); [2] P42cm (101); [2] P42nm (102); [2] P-42m (111); [2] P-421m (113); [3] P6mm (183)
II[2] Fmm2 (42); [2] Pmm2 (a' = 1/2a, b' = 1/2b) (25)








































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