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Crystal Lab › Prototype structures › Orthorhombic

Ta₂S

Orthorhombic · space group Pbcm (No. 57) · Pearson oP36

Symmetry elements and Wyckoff positions (interactive)

Ta₂S in Pbcm

Setting
Loading the group…
x = 0.10, y = 0.17, z = 0.08

Unit cell

Lattice constants
a = 7.379 Å, b = 5.574 Å, c = 15.190 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
624.8 ų
Atoms in the conventional cell
36 (S 12, Ta 24)
Formula units Z
12
Pearson symbol
oP36 — orthorhombic, primitive lattice, 36 atoms per conventional cell
Symmetry operations
8 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
S1S4c40.18090.25000.0000
Ta3Ta4d40.99100.63060.2500
Ta4Ta4d40.35280.87090.2500
S2S8e80.41320.76510.0955
Ta5Ta8e80.09690.89300.0900
Ta6Ta8e80.28410.39520.1541

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 36 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

AB2_oP36_57_ce_2d2e-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP36, then the space-group number 57, then the Wyckoff letters occupied by each element in turn (S: 4c; Ta: 4d; Ta: 4d; S: 8e; Ta: 8e; Ta: 8e). 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 AB2_oP36_57_ce_2d2e-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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