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Crystal Lab › Prototype structures › Orthorhombic

H₂S (170 GPa)

Orthorhombic · space group Cmce (No. 64) · Pearson oC24

Symmetry elements and Wyckoff positions (interactive)

H₂S (170 GPa) in Cmce

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

Unit cell

Lattice constants
a = 2.999 Å, b = 4.327 Å, c = 7.601 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
98.6 ų
Atoms in the conventional cell
24 (H 16, S 8)
Formula units Z
8
Pearson symbol
oC24 — orthorhombic, base-centred lattice, 24 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
H1H8f80.00000.37200.2700
H2H8f80.00000.60000.0920
S3S8f80.00000.37100.6150

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

A2B_oC24_64_2f_f-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 64, then the Wyckoff letters occupied by each element in turn (H: 8f; H: 8f; S: 8f). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Note: HP, Theory.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B_oC24_64_2f_f-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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