Crystal Lab › Prototype structures › Orthorhombic
NaHg
Orthorhombic · space group Cmcm (No. 63) · Pearson oC16
Symmetry elements and Wyckoff positions (interactive)
NaHg in Cmcm
SettingUnit cell
- Lattice constants
- a = 7.190 Å, b = 10.790 Å, c = 5.210 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 404.2 ų
- Atoms in the conventional cell
- 16 (Na 8, Hg 8)
- Formula units Z
- 8
- Pearson symbol
- oC16 — orthorhombic, base-centred lattice, 16 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Na2 | Na | 4c | 4 | 0.0000 | 0.3680 | 0.2500 |
| Na3 | Na | 4c | 4 | 0.0000 | 0.8140 | 0.2500 |
| Hg1 | Hg | 8g | 8 | 0.2120 | 0.0880 | 0.2500 |
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 16 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
AB_oC16_63_g_2c-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC16, then the space-group number 63, then the Wyckoff letters occupied by each element in turn (Na: 4c; Na: 4c; Hg: 8g). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB_oC16_63_g_2c-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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