Crystal Lab › Prototype structures › Tetragonal
BaGe₂As₂
Tetragonal · space group P42mc (No. 105) · Pearson tP20
Symmetry elements and Wyckoff positions (interactive)
BaGe₂As₂ in P42mc
SettingUnit cell
- Lattice constants
- a = 7.786 Å, b = 7.786 Å, c = 8.664 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 525.2 ų
- Atoms in the conventional cell
- 20 (Ba 4, Ge 8, As 8)
- Formula units Z
- 4
- Pearson symbol
- tP20 — tetragonal, primitive lattice, 20 atoms per conventional cell
- Symmetry operations
- 8 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Ba2 | Ba | 2b | 2 | 0.5000 | 0.5000 | 0.0000 |
| Ba3 | Ba | 2c | 2 | 0.0000 | 0.5000 | 0.0241 |
| Ge4 | Ge | 4d | 4 | 0.8351 | 0.0000 | 0.8640 |
| Ge5 | Ge | 4d | 4 | 0.6632 | 0.0000 | 0.1068 |
| As1 | As | 8f | 8 | 0.7290 | 0.7453 | 0.2558 |
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 20 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
A2BC2_tP20_105_f_bc_2d-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol tP20, then the space-group number 105, then the Wyckoff letters occupied by each element in turn (Ba: 2b; Ba: 2c; Ge: 4d; Ge: 4d; As: 8f). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
BaGe₂P₂ <!--beginning with an
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2BC2_tP20_105_f_bc_2d-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.