Crystal Lab › Prototype structures › Orthorhombic
γ-SeO₂ O₂Se
Orthorhombic · space group Pmc21 (No. 26) · Pearson oP24
Symmetry elements and Wyckoff positions (interactive)
γ-SeO₂ in Pmc21
SettingUnit cell
- Lattice constants
- a = 5.071 Å, b = 4.483 Å, c = 14.967 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 340.3 ų
- Atoms in the conventional cell
- 24 (O 16, Se 8)
- Formula units Z
- 8
- Pearson symbol
- oP24 — orthorhombic, primitive lattice, 24 atoms per conventional cell
- Symmetry operations
- 4 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| O1 | O | 2a | 2 | 0.0000 | 0.4760 | 0.3370 |
| O2 | O | 2a | 2 | 0.0000 | 0.0270 | 0.0900 |
| Se7 | Se | 2a | 2 | 0.0000 | 0.1070 | 0.6894 |
| Se8 | Se | 2a | 2 | 0.0000 | 0.3440 | 0.4369 |
| O3 | O | 2b | 2 | 0.5000 | 0.6170 | 0.4860 |
| O4 | O | 2b | 2 | 0.5000 | 0.1660 | 0.2250 |
| Se10 | Se | 2b | 2 | 0.5000 | 0.5110 | 0.2492 |
| Se9 | Se | 2b | 2 | 0.5000 | 0.0270 | 0.0000 |
| O5 | O | 4c | 4 | 0.2540 | 0.6240 | 0.1760 |
| O6 | O | 4c | 4 | 0.2480 | 0.0610 | 0.4190 |
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 24 atoms drawn above are these sites multiplied by all 4 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
A2B_oP24_26_2a2b2c_2a2b-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP24, then the space-group number 26, then the Wyckoff letters occupied by each element in turn (O: 2a; O: 2a; Se: 2a; Se: 2a; O: 2b; O: 2b; Se: 2b; Se: 2b; O: 4c; O: 4c). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: \gamma-SeO₂.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B_oP24_26_2a2b2c_2a2b-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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