Crystal Lab › Prototype structures › Tetragonal
CaO₂(H₂O)₈
Tetragonal · space group P4/mcc (No. 124) · Pearson tP22
Symmetry elements and Wyckoff positions (interactive)
CaO₂(H₂O)₈ in P4/mcc
SettingUnit cell
- Lattice constants
- a = 6.210 Å, b = 6.210 Å, c = 11.000 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 424.2 ų
- Atoms in the conventional cell
- 22 (Ca 2, O 4, H 16)
- Formula units Z
- 2
- Pearson symbol
- tP22 — tetragonal, primitive lattice, 22 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Ca1 | Ca | 2a | 2 | 0.0000 | 0.0000 | 0.2500 |
| O3 | O | 4h | 4 | 0.5000 | 0.5000 | 0.1900 |
| H2 | H | 16n | 16 | 0.3000 | 0.1100 | 0.1300 |
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 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
AB8C2_tP22_124_a_n_h-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 124, then the Wyckoff letters occupied by each element in turn (Ca: 2a; O: 4h; H: 16n). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
BrO₂(H₂O)₈, SrO₂(H₂O)₈ <!--beginning with an
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB8C2_tP22_124_a_n_h-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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