3.5.7 $S_{\mathrm{2}}$ symmetry

Under stress along directions other than those given in Table 3.5 the crystal loses all rotational symmetries and is invariant only under inversion. The resulting crystal class is $S_2$ and half of the BZ must be chosen as irreducible volume for band structure calculation.

E. Ungersboeck: Advanced Modelling Aspects of Modern Strained CMOS Technology