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Crystal Lab › Prototype structures › Trigonal

Cinnabar (HgS, B9)

Trigonal · space group P3221 (No. 154) · Pearson hP6 · Strukturbericht B9 · mineral: cinnabar

Symmetry elements and Wyckoff positions (interactive)

Cinnabar (HgS, B9) in P3221

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

Unit cell

Lattice constants
a = 4.145 Å, b = 4.145 Å, c = 9.496 Å; α = 90.00°, β = 90.00°, γ = 120.00°
Cell volume
141.3 ų
Atoms in the conventional cell
6 (Hg 3, S 3)
Formula units Z
3
Pearson symbol
hP6 — hexagonal / trigonal, primitive lattice, 6 atoms per conventional cell
Symmetry operations
6 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Hg1Hg3a30.71980.00000.6667
S2S3b30.48890.00000.1667

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 6 atoms drawn above are these sites multiplied by all 6 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_hP6_154_a_b-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hP6, then the space-group number 154, then the Wyckoff letters occupied by each element in turn (Hg: 3a; S: 3b). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

HgO <!--beginning with an

Note: B9, Cinnabar.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB_hP6_154_a_b-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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