Guyanaite (β-CrOOH) Structure: ABC2_oP8_31_a_a_2a-001
| Prototype | CrHO$_{2}$ |
| AFLOW prototype label | ABC2_oP8_31_a_a_2a-001 |
| Mineral name | guyanaite |
| ICSD | none |
| Pearson symbol | oP8 |
| Space group number | 31 |
| Space group symbol | $Pmn2_1$ |
| AFLOW prototype command |
aflow --proto=ABC2_oP8_31_a_a_2a-001
--params=$a, \allowbreak b/a, \allowbreak c/a, \allowbreak y_{1}, \allowbreak z_{1}, \allowbreak y_{2}, \allowbreak z_{2}, \allowbreak y_{3}, \allowbreak z_{3}, \allowbreak y_{4}, \allowbreak z_{4}$ |
Other compounds with this structure
InOOH
- CrOOH is found naturally in three forms. They are usually found together with Cr$_{2}$O$_{3}$ in a mineral known as merumite (Milton, 1976):
- Grimaldiite, rhombohedral $\alpha$–CrOOH,
- Guyanaite, orthorhombic $\beta$–CrOOH (this structure), and
- Bracewellite, orthorhombic $\gamma$–CrOOH is in the Lepidocrocite ($\gamma$–FeOOH, $E0_{4}$) structure.
- (Jahn, 2012) give the data for this structure in the $P2_{1}nm$ setting of space group #31. We use FINDSYM to transform this to the standard $Pmn2_{1}$ setting.
- Space group $Pmn2_{1}$ #31 does not specify the origin of the $z$-axis. We choose it by setting $z_{1} = 0$ for the position of the chromium atom.
\[ \begin{array}{ccc}
\mathbf{a_{1}}&=&a \,\mathbf{\hat{x}}\\\mathbf{a_{2}}&=&b \,\mathbf{\hat{y}}\\\mathbf{a_{3}}&=&c \,\mathbf{\hat{z}}
\end{array}\]
Basis vectors
| Lattice coordinates | Cartesian coordinates | Wyckoff position | Atom type | |||
|---|---|---|---|---|---|---|
| $\mathbf{B_{1}}$ | = | $y_{1} \, \mathbf{a}_{2}+z_{1} \, \mathbf{a}_{3}$ | = | $b y_{1} \,\mathbf{\hat{y}}+c z_{1} \,\mathbf{\hat{z}}$ | (2a) | Cr I |
| $\mathbf{B_{2}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}- y_{1} \, \mathbf{a}_{2}+\left(z_{1} + \frac{1}{2}\right) \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}- b y_{1} \,\mathbf{\hat{y}}+c \left(z_{1} + \frac{1}{2}\right) \,\mathbf{\hat{z}}$ | (2a) | Cr I |
| $\mathbf{B_{3}}$ | = | $y_{2} \, \mathbf{a}_{2}+z_{2} \, \mathbf{a}_{3}$ | = | $b y_{2} \,\mathbf{\hat{y}}+c z_{2} \,\mathbf{\hat{z}}$ | (2a) | H I |
| $\mathbf{B_{4}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}- y_{2} \, \mathbf{a}_{2}+\left(z_{2} + \frac{1}{2}\right) \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}- b y_{2} \,\mathbf{\hat{y}}+c \left(z_{2} + \frac{1}{2}\right) \,\mathbf{\hat{z}}$ | (2a) | H I |
| $\mathbf{B_{5}}$ | = | $y_{3} \, \mathbf{a}_{2}+z_{3} \, \mathbf{a}_{3}$ | = | $b y_{3} \,\mathbf{\hat{y}}+c z_{3} \,\mathbf{\hat{z}}$ | (2a) | O I |
| $\mathbf{B_{6}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}- y_{3} \, \mathbf{a}_{2}+\left(z_{3} + \frac{1}{2}\right) \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}- b y_{3} \,\mathbf{\hat{y}}+c \left(z_{3} + \frac{1}{2}\right) \,\mathbf{\hat{z}}$ | (2a) | O I |
| $\mathbf{B_{7}}$ | = | $y_{4} \, \mathbf{a}_{2}+z_{4} \, \mathbf{a}_{3}$ | = | $b y_{4} \,\mathbf{\hat{y}}+c z_{4} \,\mathbf{\hat{z}}$ | (2a) | O II |
| $\mathbf{B_{8}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}- y_{4} \, \mathbf{a}_{2}+\left(z_{4} + \frac{1}{2}\right) \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}- b y_{4} \,\mathbf{\hat{y}}+c \left(z_{4} + \frac{1}{2}\right) \,\mathbf{\hat{z}}$ | (2a) | O II |
References
- S. Jahn, B. Wunder, M. Koch-Müller, L. Tarrieu, M. Pöhle, A. Watenphul, and M. N. Taran, Pressure-induced hydrogen bond symmetrisation in guyanaite, β-CrOOH: evidence from spectroscopy and {\em ab initio} simulations, Eur. J. Mineral. 24, 839–850 (2012), doi:10.1127/0935-1221/2012/0024-2228.
- C. Milton, D. E. Appleman, M. H. Appleman, E. C. T. Chao, F. Cuttitta, J. I. Dinnin, E. J. Dwornik, B. L. Ingram, and J. H. J. Rose, Merumite – A Complex Assemblage of Chromium Minerals from Guyanna (1976). Geological Survey Professional Paper 887.
Prototype Generator
aflow --proto=ABC2_oP8_31_a_a_2a --params=$a,b/a,c/a,y_{1},z_{1},y_{2},z_{2},y_{3},z_{3},y_{4},z_{4}$