Crystal Lab › The 230 space groups › Trigonal
No. 166 R -3 m :h
Trigonal space group · 36 symmetry operations per cell · 9 Wyckoff positions · 2 settings
Symmetry elements and Wyckoff positions (interactive)
No. 166 R -3 m :h
SettingLoading the group…
x = 0.10, y = 0.17, z = 0.08
- Number
- 166
- Hermann–Mauguin symbol
- R -3 m :h
- Hall symbol
-R 3 2"- Crystal system
- Trigonal
- Operations per cell
- 36
- General position
- 36i (site symmetry 1)
Wyckoff positions (standard setting)
| Multiplicity | Letter | Site symmetry |
|---|---|---|
| 36 | i | 1 |
| 18 | h | .m |
| 18 | g | .2 |
| 18 | f | .2 |
| 9 | e | .2/m |
| 9 | d | .2/m |
| 6 | c | 3m |
| 3 | b | -3m |
| 3 | a | -3m |
How to read it
- Each symmetry element drawn in the cell is worked out from the group’s operations: rotation and screw axes as lines (arrow = direction; dashed = screw), mirror and glide planes as sheets (dashed outline = glide), inversion centres as dots; rotoinversion axes are dotted. Colours: 2-fold red, 3-fold green, 4-fold blue, 6-fold purple.
- The multiplicity is how many equivalent points an atom on that site generates in the conventional cell; the general position has the highest multiplicity, equal to the number of operations.
- Site symmetry is the point group that leaves that position fixed; a special position (lower multiplicity) sits on a symmetry element — press + on a row to see its atoms land on the drawn elements.
Crystal Lab structures in this group
- Cadmium chloride (CdCl₂) — Layered AB₂, 6:3
- Lithium cobalt oxide (layered) (LiCoO₂) — Layered rock-salt (α-NaFeO₂ type)