Crystal Lab › The 230 space groups › Monoclinic
No. 3 P 1 2 1
Monoclinic space group · 2 symmetry operations per cell · 5 Wyckoff positions · 3 settings
Symmetry elements and Wyckoff positions (interactive)
No. 3 P 1 2 1
SettingLoading the group…
x = 0.10, y = 0.17, z = 0.08
- Number
- 3
- Hermann–Mauguin symbol
- P 1 2 1
- Hall symbol
P 2y- Crystal system
- Monoclinic
- Operations per cell
- 2
- General position
- 2e (site symmetry 1)
Wyckoff positions (standard setting)
| Multiplicity | Letter | Site symmetry |
|---|---|---|
| 2 | e | 1 |
| 1 | d | 2 |
| 1 | c | 2 |
| 1 | b | 2 |
| 1 | a | 2 |
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.