Crystal Lab › Prototype structures › Cubic
Si₃₄ Clathrate
Cubic · space group Fd-3m (No. 227) · Pearson cF136
Symmetry elements and Wyckoff positions (interactive)
Si₃₄ Clathrate in Fd-3m
SettingUnit cell
- Lattice constants
- a = 14.864 Å, b = 14.864 Å, c = 14.864 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 3284.0 ų
- Atoms in the conventional cell
- 136 (Si 136)
- Formula units Z
- 136
- Pearson symbol
- cF136 — cubic, face-centred lattice, 136 atoms per conventional cell
- Symmetry operations
- 192 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Si1 | Si | 8a | 8 | 0.1250 | 0.1250 | 0.1250 |
| Si2 | Si | 32e | 32 | 0.2624 | 0.2624 | 0.2624 |
| Si3 | Si | 96g | 96 | 0.1824 | 0.1824 | 0.3701 |
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 136 atoms drawn above are these sites multiplied by all 192 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
A_cF136_227_aeg-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol cF136, then the space-group number 227, then the Wyckoff letters occupied by each element in turn (Si: 8a; Si: 32e; Si: 96g). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
Ge (high pressure) <!--beginning with an
Note: Clathrate.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A_cF136_227_aeg-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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