Fig. 1
Supercells of \(\{10\bar{1}1\}\) (1 × 1 × 80, 80 atoms) and \(\{10\bar{1}2\}\) twins (1 × 1 × 60, 60 atoms) which are indicated by rectangles. Vector \(\overrightarrow{a}\) is the plane normal of the displacement plane (i.e. \(\mathrm{1/3}\langle 1\bar{2}10\rangle\) in both cases), \(\overrightarrow{b}\) is parallel to the displacement direction (see “TD” in Table 1), \(\overrightarrow{c}\) is perpendicular to the twin boundary. a glide twin of \(\{10\bar{1}1\}\), b reflection twin of \(\{10\bar{1}1\}\), c Glide twin of \(\{10\bar{1}2\}\), d reflection twin of \(\{10\bar{1}2\}\). The black lines indicate the atoms in the centers of the TBs. The basal planes are denoted by red lines. When compressive stress is exerted perpendicular to the basal plane, the compression twins nucleate and grow; when tensile stress is exerted, the tensile twins form. For metals with c/a < 1.633, e.g. Mg, \(\{10\bar{1}1\}\) is a compression twinning plane, while \(\{10\bar{1}2\}\) a tensile twinning plane. For more details see ref. 3
