$\alpha$–FeSe Structure: AB_oC8_67_a_g

Picture of Structure; Click for Big Picture
Prototype : FeSe
AFLOW prototype label : AB_oC8_67_a_g
Strukturbericht designation : None
Pearson symbol : oC8
Space group number : 67
Space group symbol : $Cmma$
AFLOW prototype command : aflow --proto=AB_oC8_67_a_g
--params=
$a$,$b/a$,$c/a$,$z_{2}$


  • We follow the reference in calling this $\alpha$–FeSe. Some other authorities refer to the $B10$ (PbO)–like phase of FeSe as $\alpha$–FeSe, calling this phase $\beta$–FeSe. The authors note that the Se ion concentration is close to 1. The data is presented for the structure at 7 K. $\alpha$–FeSe ($\alpha$–FeSe AB_oC8_67_a_g) and $\alpha$–PbO ($\alpha$–PbO AB_oC8_67_a_g) have the same AFLOW prototype label. They are generated by the same symmetry operations with different sets of parameters (––params) specified in their corresponding CIF files.

Base-centered Orthorhombic primitive vectors:

\[ \begin{array}{ccc} \mathbf{a}_1 & = & \frac12 \, a \, \mathbf{\hat{x}} - \frac12 \, b \, \mathbf{\hat{y}} \\ \mathbf{a}_2 & = & \frac12 \, a \, \mathbf{\hat{x}} + \frac12 \, b \, \mathbf{\hat{y}} \\ \mathbf{a}_3 & = & c \, \mathbf{\hat{z}} \\ \end{array} \]

Basis vectors:

\[ \begin{array}{ccccccc} & & \mbox{Lattice Coordinates} & & \mbox{Cartesian Coordinates} &\mbox{Wyckoff Position} & \mbox{Atom Type} \\ \mathbf{B}_{1} & = & \frac{1}{4} \, \mathbf{a}_{1} + \frac{1}{4} \, \mathbf{a}_{2} & = & \frac{1}{4}a \, \mathbf{\hat{x}} & \left(4a\right) & \mbox{Fe} \\ \mathbf{B}_{2} & = & \frac{3}{4} \, \mathbf{a}_{1} + \frac{3}{4} \, \mathbf{a}_{2} & = & \frac{3}{4}a \, \mathbf{\hat{x}} & \left(4a\right) & \mbox{Fe} \\ \mathbf{B}_{3} & = & \frac{3}{4} \, \mathbf{a}_{1} + \frac{1}{4} \, \mathbf{a}_{2} + z_{2} \, \mathbf{a}_{3} & = & \frac{1}{2}a \, \mathbf{\hat{x}}- \frac{1}{4}b \, \mathbf{\hat{y}} + z_{2}c \, \mathbf{\hat{z}} & \left(4g\right) & \mbox{Se} \\ \mathbf{B}_{4} & = & \frac{1}{4} \, \mathbf{a}_{1} + \frac{3}{4} \, \mathbf{a}_{2}-z_{2} \, \mathbf{a}_{3} & = & \frac{1}{2}a \, \mathbf{\hat{x}} + \frac{1}{4}b \, \mathbf{\hat{y}}-z_{2}c \, \mathbf{\hat{z}} & \left(4g\right) & \mbox{Se} \\ \end{array} \]

References

  • D. Louca, K. Horigane, A. Llobet, R. Arita, S. Ji, N. Katayama, S. Konbu, K. Nakamura, T.–Y. Koo, P. Tong, and K. Yamada, Local atomic structure of superconducting FeSe1–xTex, Phys. Rev. B 81, 134524 (2010), doi:10.1103/PhysRevB.81.134524.

Geometry files


Prototype Generator

aflow --proto=AB_oC8_67_a_g --params=

Species:

Running:

Output: