Crystal Lab › Prototype structures › Tetragonal
La Se_{1.85} LaSe₂
Tetragonal · space group P4/nmm (No. 129) · Pearson tP6
Symmetry elements and Wyckoff positions (interactive)
La Se_{1.85} in P4/nmm
SettingUnit cell
- Lattice constants
- a = 4.207 Å, b = 4.207 Å, c = 17.023 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 301.3 ų
- Atoms in the conventional cell
- 6 (Se 4, La 2)
- Formula units Z
- 2
- Pearson symbol
- tP6 — tetragonal, primitive lattice, 6 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Se1 | Se | 2a | 2 | 0.7500 | 0.2500 | 0.0000 |
| La2 | La | 2c | 2 | 0.2500 | 0.2500 | 0.1370 |
| Se3 | Se | 2c | 2 | 0.2500 | 0.2500 | 0.3181 |
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 6 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
AB2_tP6_129_c_ac-003: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol tP6, then the space-group number 129, then the Wyckoff letters occupied by each element in turn (Se: 2a; La: 2c; Se: 2c). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
CeSe_{1.83}, NdSe_{1.83}, SmSe_{1.84} <!--beginning with an
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB2_tP6_129_c_ac-003 (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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