Crystal Lab › Prototype structures › Trigonal
Predicted Li₂MgH₁₆ 300 GPa H₁₆Li₂Mg
Trigonal · space group P-3m1 (No. 164) · Pearson hP19
Symmetry elements and Wyckoff positions (interactive)
Predicted Li₂MgH₁₆ 300 GPa in P-3m1
SettingUnit cell
- Lattice constants
- a = 2.796 Å, b = 2.796 Å, c = 5.313 Å; α = 90.00°, β = 90.00°, γ = 120.00°
- Cell volume
- 36.0 ų
- Atoms in the conventional cell
- 19 (Mg 1, H 16, Li 2)
- Formula units Z
- 1
- Pearson symbol
- hP19 — hexagonal / trigonal, primitive lattice, 19 atoms per conventional cell
- Symmetry operations
- 12 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Mg6 | Mg | 1a | 1 | 0.0000 | 0.0000 | 0.0000 |
| H1 | H | 2d | 2 | 0.3333 | 0.6667 | 0.0745 |
| H2 | H | 2d | 2 | 0.3333 | 0.6667 | 0.8914 |
| Li5 | Li | 2d | 2 | 0.3333 | 0.6667 | 0.3363 |
| H3 | H | 6i | 6 | 0.1716 | 0.8284 | 0.5797 |
| H4 | H | 6i | 6 | 0.1644 | 0.8356 | 0.7365 |
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 19 atoms drawn above are these sites multiplied by all 12 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
A16B2C_hP19_164_2d2i_d_a-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hP19, then the space-group number 164, then the Wyckoff letters occupied by each element in turn (Mg: 1a; H: 2d; H: 2d; Li: 2d; H: 6i; H: 6i). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: Predicted, 300 GPa.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A16B2C_hP19_164_2d2i_d_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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