Crystal Lab › Prototype structures › Orthorhombic
NH₄H₂PO₂ (F5₇)
Orthorhombic · space group Cmme (No. 67) · Pearson oC24 · Strukturbericht F57
Symmetry elements and Wyckoff positions (interactive)
NH₄H₂PO₂ (F5₇) in Cmme
SettingUnit cell
- Lattice constants
- a = 11.470 Å, b = 7.570 Å, c = 3.980 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 345.6 ų
- Atoms in the conventional cell
- 24 (N 4, P 4, H 8, O 8)
- Formula units Z
- 4
- Pearson symbol
- oC24 — orthorhombic, base-centred lattice, 24 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| N2 | N | 4a | 4 | 0.2500 | 0.0000 | 0.0000 |
| P4 | P | 4g | 4 | 0.0000 | 0.2500 | 0.4580 |
| H1 | H | 8m | 8 | 0.0000 | 0.6080 | 0.8060 |
| O3 | O | 8n | 8 | 0.3860 | 0.2500 | 0.3480 |
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 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
A2BC2D_oC24_67_m_a_n_g-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC24, then the space-group number 67, then the Wyckoff letters occupied by each element in turn (N: 4a; P: 4g; H: 8m; O: 8n). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: F5₇.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2BC2D_oC24_67_m_a_n_g-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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