Crystal Lab › Prototype structures › Orthorhombic
Archerite (KH₂PO₄)
Orthorhombic · space group Fdd2 (No. 43) · Pearson oF64 · mineral: archerite
Symmetry elements and Wyckoff positions (interactive)
Archerite (KH₂PO₄) in Fdd2
SettingUnit cell
- Lattice constants
- a = 10.530 Å, b = 10.440 Å, c = 6.900 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 758.5 ų
- Atoms in the conventional cell
- 64 (K 8, P 8, H 16, O 32)
- Formula units Z
- 8
- Pearson symbol
- oF64 — orthorhombic, face-centred lattice, 64 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| K2 | K | 8a | 8 | 0.0000 | 0.0000 | 0.4880 |
| P5 | P | 8a | 8 | 0.0000 | 0.0000 | 0.0000 |
| H1 | H | 16b | 16 | 0.0620 | 0.7125 | 0.6145 |
| O3 | O | 16b | 16 | 0.1340 | 0.7845 | 0.6190 |
| O4 | O | 16b | 16 | 0.2845 | 0.8660 | 0.8735 |
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 64 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
A2BC4D_oF64_43_b_a_2b_a-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oF64, then the space-group number 43, then the Wyckoff letters occupied by each element in turn (K: 8a; P: 8a; H: 16b; O: 16b; O: 16b). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: Archerite.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2BC4D_oF64_43_b_a_2b_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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