Crystal Lab › Prototype structures › Orthorhombic
HgBr₂ (C24)
Orthorhombic · space group Cmc21 (No. 36) · Pearson oC12 · Strukturbericht C24
Symmetry elements and Wyckoff positions (interactive)
HgBr₂ (C24) in Cmc21
SettingUnit cell
- Lattice constants
- a = 4.624 Å, b = 6.789 Å, c = 12.445 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 390.7 ų
- Atoms in the conventional cell
- 12 (Br 8, Hg 4)
- Formula units Z
- 4
- Pearson symbol
- oC12 — orthorhombic, base-centred lattice, 12 atoms per conventional cell
- Symmetry operations
- 8 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Br1 | Br | 4a | 4 | 0.0000 | 0.0610 | 0.1340 |
| Br2 | Br | 4a | 4 | 0.0000 | 0.3950 | 0.3660 |
| Hg3 | Hg | 4a | 4 | 0.0000 | 0.3330 | 0.0000 |
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 12 atoms drawn above are these sites multiplied by all 8 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
A2B_oC12_36_2a_a-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC12, then the space-group number 36, then the Wyckoff letters occupied by each element in turn (Br: 4a; Br: 4a; Hg: 4a). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
β-HgI₂ <!--beginning with an
Note: C24.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B_oC12_36_2a_a-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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