Crystal Lab › Prototype structures › Tetragonal
Tl₄HgI₆
Tetragonal · space group P4nc (No. 104) · Pearson tP22
Symmetry elements and Wyckoff positions (interactive)
Tl₄HgI₆ in P4nc
SettingUnit cell
- Lattice constants
- a = 9.394 Å, b = 9.394 Å, c = 9.222 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 813.8 ų
- Atoms in the conventional cell
- 22 (Hg 2, I 12, Tl 8)
- Formula units Z
- 2
- Pearson symbol
- tP22 — tetragonal, primitive lattice, 22 atoms per conventional cell
- Symmetry operations
- 8 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Hg1 | Hg | 2a | 2 | 0.0000 | 0.0000 | 0.7860 |
| I2 | I | 2a | 2 | 0.0000 | 0.0000 | 0.5000 |
| I3 | I | 2a | 2 | 0.0000 | 0.0000 | 0.0649 |
| I4 | I | 8c | 8 | 0.8297 | 0.6458 | 0.2860 |
| Tl5 | Tl | 8c | 8 | 0.6491 | 0.8588 | 0.0360 |
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 22 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
AB6C4_tP22_104_a_2ac_c-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol tP22, then the space-group number 104, then the Wyckoff letters occupied by each element in turn (Hg: 2a; I: 2a; I: 2a; I: 8c; Tl: 8c). 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 AB6C4_tP22_104_a_2ac_c-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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