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Crystal Lab › Prototype structures › Orthorhombic

URe₂

Orthorhombic · space group Cmcm (No. 63) · Pearson oC24

Symmetry elements and Wyckoff positions (interactive)

URe₂ in Cmcm

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

Unit cell

Lattice constants
a = 5.600 Å, b = 9.178 Å, c = 8.463 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
435.0 ų
Atoms in the conventional cell
24 (Re 16, U 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
Re1Re4a40.00000.00000.0000
Re2Re4c40.00000.83330.2500
U4U8f80.00000.33330.0625
Re3Re8g80.25000.08330.2500

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 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_63_acg_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 63, then the Wyckoff letters occupied by each element in turn (Re: 4a; Re: 4c; U: 8f; Re: 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 A2B_oC24_63_acg_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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