Symmetry elements and Wyckoff positions (interactive)
Cd₈As₇Cl in P23
SettingUnit cell
- Lattice constants
- a = 7.266 Å, b = 7.266 Å, c = 7.266 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 383.6 ų
- Atoms in the conventional cell
- 20 (As 7, Cl 1, Cd 12)
- Formula units Z
- 1
- Pearson symbol
- cP20 — cubic, primitive lattice, 20 atoms per conventional cell
- Symmetry operations
- 12 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| As1 | As | 1a | 1 | 0.0000 | 0.0000 | 0.0000 |
| Cl2 | Cl | 1b | 1 | 0.5000 | 0.5000 | 0.5000 |
| Cd3 | Cd | 4e | 4 | 0.2170 | 0.2170 | 0.2170 |
| Cd4 | Cd | 4e | 4 | 0.7158 | 0.7158 | 0.7158 |
| Cd5 | Cd | 4e | 4 | 0.7637 | 0.7637 | 0.7637 |
| As6 | As | 6g | 6 | 0.3328 | 0.0000 | 0.5000 |
The multiplicity and the Wyckoff letter say how many copies of the site the group makes in one cell and on which kind of symmetry element the site sits; the 20 atoms drawn above are these sites multiplied by all 12 operations. Press Wyckoff under Colour to see the sites, and tick a symmetry element on the left to see which atoms lie on it.
How to read the label
A7B12C_cP20_195_ag_3e_b-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol cP20, then the space-group number 195, then the Wyckoff letters occupied by each element in turn (As: 1a; Cl: 1b; Cd: 4e; Cd: 4e; Cd: 4e; As: 6g). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A7B12C_cP20_195_ag_3e_b-001 (M. J. Mehl et al., Comput. Mater. Sci. 136, S1 (2017); D. Hicks et al., ibid. 161, S1 (2019) and 199, 110450 (2021); S. Eckert et al., ibid. 240, 112988 (2024)). Symmetry elements, Wyckoff assignment and the diagram are computed on this page from the group operations.
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