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Crystal Lab › Prototype structures › Tetragonal

CaO₂(H₂O)₈

Tetragonal · space group P4/mcc (No. 124) · Pearson tP22

Symmetry elements and Wyckoff positions (interactive)

CaO₂(H₂O)₈ in P4/mcc

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

Unit cell

Lattice constants
a = 6.210 Å, b = 6.210 Å, c = 11.000 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
424.2 ų
Atoms in the conventional cell
22 (Ca 2, O 4, H 16)
Formula units Z
2
Pearson symbol
tP22 — tetragonal, primitive lattice, 22 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Ca1Ca2a20.00000.00000.2500
O3O4h40.50000.50000.1900
H2H16n160.30000.11000.1300

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 22 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

AB8C2_tP22_124_a_n_h-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol tP22, then the space-group number 124, then the Wyckoff letters occupied by each element in turn (Ca: 2a; O: 4h; H: 16n). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

BrO₂(H₂O)₈, SrO₂(H₂O)₈ <!--beginning with an

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB8C2_tP22_124_a_n_h-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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