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Crystal Lab › Prototype structures › Monoclinic

SiAs

Monoclinic · space group C12/m1 (No. 12) · Pearson mC24

Symmetry elements and Wyckoff positions (interactive)

SiAs in C12/m1

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

Unit cell

Lattice constants
a = 15.980 Å, b = 3.668 Å, c = 9.529 Å; α = 90.00°, β = 106.00°, γ = 90.00°
Cell volume
536.9 ų
Atoms in the conventional cell
24 (As 12, Si 12)
Formula units Z
12
Pearson symbol
mC24 — monoclinic, base-centred lattice, 24 atoms per conventional cell
Symmetry operations
8 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
As1As4i40.33680.00000.8262
As2As4i40.03690.00000.8239
As3As4i40.65210.00000.5457
Si4Si4i40.73870.00000.7924
Si5Si4i40.63030.00000.9162
Si6Si4i40.06610.00000.5884

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 24 atoms drawn above are these sites multiplied by all 8 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

AB_mC24_12_3i_3i-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol mC24, then the space-group number 12, then the Wyckoff letters occupied by each element in turn (As: 4i; As: 4i; As: 4i; Si: 4i; Si: 4i; Si: 4i). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

GaTe, GeAs <!--beginning with an

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB_mC24_12_3i_3i-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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