NH$_{4}$HgCl$_{3}$ ($E2_{5}$) Structure: A3BC_tP5_123_ah_c_b-001
| Prototype | Cl$_{3}$H$_{4}$HgN$_{4}$ |
| AFLOW prototype label | A3BC_tP5_123_ah_c_b-001 |
| Strukturbericht designation | $E2_{5}$ |
| ICSD | 15962 |
| Pearson symbol | tP5 |
| Space group number | 123 |
| Space group symbol | $P4/mmm$ |
| AFLOW prototype command |
aflow --proto=A3BC_tP5_123_ah_c_b-001
--params=$a, \allowbreak c/a, \allowbreak z_{4}$ |
- The positions of the hydrogen atoms are not given. It is likely that the hydrogen atoms are freely rotating around the nitrogen, as any reasonable fixed positions would destroy both the inversion symmetry and the four-fold rotation axis exhibited by space group $P4/mmm$ #123.
- (Harmsen, 1939) and (Herrmann, 1943) give multiple possible space groups for this structure. We have chosen the highest symmetry representation, space group $P4/mmm$.
\[ \begin{array}{ccc}
\mathbf{a_{1}}&=&a \,\mathbf{\hat{x}}\\\mathbf{a_{2}}&=&a \,\mathbf{\hat{y}}\\\mathbf{a_{3}}&=&c \,\mathbf{\hat{z}}
\end{array}\]
Basis vectors
| Lattice coordinates | Cartesian coordinates | Wyckoff position | Atom type | |||
|---|---|---|---|---|---|---|
| $\mathbf{B_{1}}$ | = | $0$ | = | $0$ | (1a) | Cl I |
| $\mathbf{B_{2}}$ | = | $\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}c \,\mathbf{\hat{z}}$ | (1b) | NH I |
| $\mathbf{B_{3}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}+\frac{1}{2} \, \mathbf{a}_{2}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}a \,\mathbf{\hat{y}}$ | (1c) | Hg I |
| $\mathbf{B_{4}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}+\frac{1}{2} \, \mathbf{a}_{2}+z_{4} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}a \,\mathbf{\hat{y}}+c z_{4} \,\mathbf{\hat{z}}$ | (2h) | Cl II |
| $\mathbf{B_{5}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}+\frac{1}{2} \, \mathbf{a}_{2}- z_{4} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}a \,\mathbf{\hat{y}}- c z_{4} \,\mathbf{\hat{z}}$ | (2h) | Cl II |
References
- E. J. Harmsen, The Crystal Structure of NH$_{4}$HgCl$_{3}$, Z. Kristallogr. 100, 208–211 (1939), doi:10.1524/zkri.1939.100.1.208.
Found in
- K. Herrmann, ed., Strukturbericht Band VII 1939 (Akademische Verlagsgesellschaft M. B. H., Leipzig, 1943).
Prototype Generator
aflow --proto=A3BC_tP5_123_ah_c_b --params=$a,c/a,z_{4}$