Hypothetical BCT5 Si Structure: A_tI4_139_e
| Prototype | : | Si |
| AFLOW prototype label | : | A_tI4_139_e |
| Strukturbericht designation | : | None |
| Pearson symbol | : | tI4 |
| Space group number | : | 139 |
| Space group symbol | : | $\mbox{I4/mmm}$ |
| AFLOW prototype command | : | aflow --proto=A_tI4_139_e --params=$a,c/a,z_{1}$ |
- The bct5 structure is a tetragonal analog of the diamond (A4) structure, with 5-fold coordination. It was proposed in (Boyer, 1991) as a low energy, metastable phase of silicon, based on first-principles calculations and model potentials. To the best of our knowledge, this has not been observed experimentally. A search of Pearson's Handbook does not show any compound with this structure.
Body-centered Tetragonal primitive vectors:
\[
\begin{array}{ccc}
\mathbf{a}_1 & = & - \frac12 \, a \, \mathbf{\hat{x}} + \frac12 \, a \, \mathbf{\hat{y}} + \frac12 \, c \, \mathbf{\hat{z}}\\
\mathbf{a}_2 & = & ~ \frac12 \, a \, \mathbf{\hat{x}} - \frac12 \, a \, \mathbf{\hat{y}} + \frac12 \, c \, \mathbf{\hat{z}}\\
\mathbf{a}_3 & = & ~ \frac12 \, a \, \mathbf{\hat{x}} + \frac12 \, a \, \mathbf{\hat{y}} - \frac12 \, c \, \mathbf{\hat{z}}\\
\end{array}
\]
Basis vectors:
\[ \begin{array}{ccccccc} & & \mbox{Lattice Coordinates} & & \mbox{Cartesian Coordinates} &\mbox{Wyckoff Position} & \mbox{Atom Type} \\ \mathbf{B}_{1} & =&z_{1} \, \mathbf{a}_{1}+ z_{1} \, \mathbf{a}_{2}& =&+ z_{1} \, c \, \mathbf{\hat{z}}& \left(4e\right) & \mbox{Si} \\ \mathbf{B}_{2} & =&- z_{1} \, \mathbf{a}_{1}- z_{1} \, \mathbf{a}_{2}& =&- z_{1} \, c \, \mathbf{\hat{z}}& \left(4e\right) & \mbox{Si} \\ \end{array} \]References
- L. L. Boyer, E. Kaxiras, J. L. Feldman, J. Q. Broughton, and M. J. Mehl, New low–energy crystal structure for silicon, Phys. Rev. Lett. 67, 715–718 (1991), doi:10.1103/PhysRevLett.67.715.