Crystal Lab › Prototype structures › Orthorhombic
NH₄NO₃ IV (G0₁₁)
Orthorhombic · space group Pmmn (No. 59) · Pearson oP18 · Strukturbericht G011
Symmetry elements and Wyckoff positions (interactive)
NH₄NO₃ IV (G0₁₁) in Pmmn
SettingUnit cell
- Lattice constants
- a = 5.438 Å, b = 5.745 Å, c = 4.942 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 154.4 ų
- Atoms in the conventional cell
- 18 (N 4, O 6, H 8)
- Formula units Z
- 2
- Pearson symbol
- oP18 — orthorhombic, primitive lattice, 18 atoms per conventional cell
- Symmetry operations
- 8 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| N3 | N | 2a | 2 | 0.2500 | 0.2500 | 0.4933 |
| O5 | O | 2a | 2 | 0.2500 | 0.2500 | 0.2371 |
| N4 | N | 2b | 2 | 0.2500 | 0.7500 | 0.0836 |
| H2 | H | 4e | 4 | 0.2500 | 0.8955 | 0.1898 |
| O6 | O | 4e | 4 | 0.2500 | 0.0656 | 0.6168 |
| H1 | H | 4f | 4 | 0.8989 | 0.2500 | 0.0324 |
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 18 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
A4B2C3_oP18_59_ef_ab_ae-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP18, then the space-group number 59, then the Wyckoff letters occupied by each element in turn (N: 2a; O: 2a; N: 2b; H: 4e; O: 4e; H: 4f). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: G0₁₁, NH₄NO₃ IV.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A4B2C3_oP18_59_ef_ab_ae-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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