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Crystal Lab › Prototype structures › Tetragonal

Mercury Cyanide [Hg(CN)₂, F1₁]

Tetragonal · space group I-42d (No. 122) · Pearson tI40 · Strukturbericht F11 · mineral: mercury cyanide

Symmetry elements and Wyckoff positions (interactive)

Mercury Cyanide [Hg(CN)₂, F1₁] in I-42d

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

Unit cell

Lattice constants
a = 9.692 Å, b = 9.692 Å, c = 8.902 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
836.2 ų
Atoms in the conventional cell
40 (Hg 8, C 16, N 16)
Formula units Z
8
Pearson symbol
tI40 — tetragonal, body-centred lattice, 40 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Hg2Hg8d80.21200.25000.1250
C1C16e160.70350.42710.6785
N3N16e160.70500.54640.6639

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 40 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

A2BC2_tI40_122_e_d_e-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol tI40, then the space-group number 122, then the Wyckoff letters occupied by each element in turn (Hg: 8d; C: 16e; N: 16e). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Note: F1₁, Mercury Cyanide.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2BC2_tI40_122_e_d_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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