Figure 17.

Band structure of FeSi, calculated for variation of the chirality by changing the position parameters $u_{\mathrm{Fe}}$ and $u_{\mathrm{Si}}$. From left to right: (a) $F\overline{4}3m$ achiral, (b) $P{2}_{1}3$ at 60 GPa pressure, (c) $P{2}_{1}3$ optimized, (d) $P{2}_{1}3$ with $S^2=1$, and (e) $P{4}_{3}21$ also with $S^2=1$. Calculations are for variation of the position parameter at optimized lattice parameter a for each structure. Note that the $\Delta$ direction ($\overline{\Gamma X}$) has in space group 198 only a 2-fold rotational symmetry, therefore, the perpendicular directions $\overline{MX}$ and $\overline{X{M}^{\prime }}$ are not equivalent. (Please note the different Brillouin zone of the face-centered space group in (a)).