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Crystal Lab › Prototype structures › Orthorhombic

β-ThI₃ I₃Th

Orthorhombic · space group Cccm (No. 66) · Pearson oC64

Symmetry elements and Wyckoff positions (interactive)

β-ThI₃ in Cccm

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

Unit cell

Lattice constants
a = 20.297 Å, b = 8.735 Å, c = 14.661 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
2599.3 ų
Atoms in the conventional cell
64 (Th 16, I 48)
Formula units Z
16
Pearson symbol
oC64 — orthorhombic, base-centred lattice, 64 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Th5Th4a40.00000.00000.2500
Th6Th4c40.00000.00000.0000
I1I8k80.25000.25000.1826
I2I8l80.69940.03180.0000
Th7Th8l80.67160.67300.0000
I3I16m160.95100.71060.1302
I4I16m160.87730.88670.3708

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 64 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

A3B_oC64_66_kl2m_acl-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC64, then the space-group number 66, then the Wyckoff letters occupied by each element in turn (Th: 4a; Th: 4c; I: 8k; I: 8l; Th: 8l; I: 16m; I: 16m). 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 A3B_oC64_66_kl2m_acl-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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