Crystal Lab › Prototype structures › Orthorhombic
Hg₃S₂I₂
Orthorhombic · space group Imma (No. 74) · Pearson oI56
Symmetry elements and Wyckoff positions (interactive)
Hg₃S₂I₂ in Imma
SettingUnit cell
- Lattice constants
- a = 18.703 Å, b = 9.799 Å, c = 9.462 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 1734.2 ų
- Atoms in the conventional cell
- 56 (I 16, Hg 24, S 16)
- Formula units Z
- 8
- Pearson symbol
- oI56 — orthorhombic, body-centred lattice, 56 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| I4 | I | 4e | 4 | 0.0000 | 0.2500 | 0.9858 |
| I5 | I | 4e | 4 | 0.0000 | 0.2500 | 0.5086 |
| Hg1 | Hg | 8f | 8 | 0.8506 | 0.0000 | 0.0000 |
| Hg3 | Hg | 8h | 8 | 0.0000 | 0.9857 | 0.2525 |
| Hg2 | Hg | 8i | 8 | 0.8630 | 0.2500 | 0.2906 |
| I6 | I | 8i | 8 | 0.7519 | 0.2500 | 0.5195 |
| S7 | S | 16j | 16 | 0.8722 | 0.0073 | 0.2524 |
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 56 atoms drawn above are these sites multiplied by all 16 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
A3B2C2_oI56_74_fhi_2ei_j-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oI56, then the space-group number 74, then the Wyckoff letters occupied by each element in turn (I: 4e; I: 4e; Hg: 8f; Hg: 8h; Hg: 8i; I: 8i; S: 16j). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
Hg₃Se₂I₂ <!--beginning with an
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A3B2C2_oI56_74_fhi_2ei_j-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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