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Crystal Lab › Prototype structures › Orthorhombic

β-SeO₂ O₂Se

Orthorhombic · space group Pmc21 (No. 26) · Pearson oP12

Symmetry elements and Wyckoff positions (interactive)

β-SeO₂ in Pmc21

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

Unit cell

Lattice constants
a = 5.072 Å, b = 4.470 Å, c = 7.531 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
170.8 ų
Atoms in the conventional cell
12 (O 8, Se 4)
Formula units Z
4
Pearson symbol
oP12 — orthorhombic, primitive lattice, 12 atoms per conventional cell
Symmetry operations
4 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
O1O2a20.00000.74600.6720
Se4Se2a20.00000.12190.3748
O2O2b20.50000.62000.9610
Se5Se2b20.50000.25160.0000
O3O4c40.24700.15200.8410

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 12 atoms drawn above are these sites multiplied by all 4 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_oP12_26_abc_ab-002: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP12, then the space-group number 26, then the Wyckoff letters occupied by each element in turn (O: 2a; Se: 2a; O: 2b; Se: 2b; O: 4c). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Note: \beta-SeO₂.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B_oP12_26_abc_ab-002 (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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