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Crystal Lab › Prototype structures › Monoclinic

EuFeAs₂

Monoclinic · space group P121/m1 (No. 11) · Pearson mP8

Symmetry elements and Wyckoff positions (interactive)

EuFeAs₂ in P121/m1

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

Unit cell

Lattice constants
a = 3.982 Å, b = 3.899 Å, c = 10.666 Å; α = 90.00°, β = 90.24°, γ = 90.00°
Cell volume
165.6 ų
Atoms in the conventional cell
8 (As 4, Eu 2, Fe 2)
Formula units Z
2
Pearson symbol
mP8 — monoclinic, primitive lattice, 8 atoms per conventional cell
Symmetry operations
4 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
As1As2e20.74960.25000.3666
As2As2e20.24980.25000.0035
Eu3Eu2e20.75400.25000.7716
Fe4Fe2e20.25000.25000.5000

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 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

A2BC_mP8_11_2e_e_e-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol mP8, then the space-group number 11, then the Wyckoff letters occupied by each element in turn (As: 2e; As: 2e; Eu: 2e; Fe: 2e). 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 A2BC_mP8_11_2e_e_e-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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