Crystal Lab › Prototype structures › Orthorhombic
High-pressure GaAs AsGa
Orthorhombic · space group Imm2 (No. 44) · Pearson oI4
Symmetry elements and Wyckoff positions (interactive)
High-pressure GaAs in Imm2
SettingUnit cell
- Lattice constants
- a = 4.920 Å, b = 4.790 Å, c = 2.635 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 62.1 ų
- Atoms in the conventional cell
- 4 (As 2, Ga 2)
- Formula units Z
- 2
- Pearson symbol
- oI4 — orthorhombic, body-centred lattice, 4 atoms per conventional cell
- Symmetry operations
- 8 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| As1 | As | 2a | 2 | 0.0000 | 0.0000 | 0.0000 |
| Ga2 | Ga | 2b | 2 | 0.0000 | 0.5000 | 0.4250 |
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 4 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
AB_oI4_44_a_b-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oI4, then the space-group number 44, then the Wyckoff letters occupied by each element in turn (As: 2a; Ga: 2b). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: > 24 GPa.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB_oI4_44_a_b-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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