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Crystal Lab › Prototype structures › Orthorhombic

Black Phosphorus (A17)

Orthorhombic · space group Cmce (No. 64) · Pearson oC8 · Strukturbericht A17

Symmetry elements and Wyckoff positions (interactive)

Black Phosphorus (A17) in Cmce

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

Unit cell

Lattice constants
a = 3.314 Å, b = 10.478 Å, c = 4.376 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
151.9 ų
Atoms in the conventional cell
8 (P 8)
Formula units Z
8
Pearson symbol
oC8 — orthorhombic, base-centred lattice, 8 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
P1P8f80.00000.10170.0806

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 8 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

A_oC8_64_f-002: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC8, then the space-group number 64, then the Wyckoff letters occupied by each element in turn (P: 8f). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Note: A17, Black Phosphorus.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A_oC8_64_f-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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