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Crystal Lab › Prototype structures › Orthorhombic

HoCuP₂

Orthorhombic · space group Cmme (No. 67) · Pearson oC16

Symmetry elements and Wyckoff positions (interactive)

HoCuP₂ in Cmme

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

Unit cell

Lattice constants
a = 5.273 Å, b = 5.305 Å, c = 9.645 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
269.8 ų
Atoms in the conventional cell
16 (Cu 4, P 8, Ho 4)
Formula units Z
4
Pearson symbol
oC16 — orthorhombic, base-centred lattice, 16 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Cu1Cu4a40.25000.00000.0000
P3P4b40.25000.00000.5000
Ho2Ho4g40.00000.25000.2650
P4P4g40.00000.25000.8403

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 16 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

ABC2_oC16_67_a_g_bg-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC16, then the space-group number 67, then the Wyckoff letters occupied by each element in turn (Cu: 4a; P: 4b; Ho: 4g; P: 4g). 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 ABC2_oC16_67_a_g_bg-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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