  The growth process of of (-1012) twins is studied in Magnesium using
atomistic simulations. Two twin seeds are considered and both cases, a specific
interface, which places face-to-face prismatic and basal planes, plays an
important role. This interface has a low energy corresponding to a cusp in the
orientation-dependent interface energy of a twinned bicrystal. This interface
appears in several published twin structures and for instance accommodates the
large deviations of twin interfaces from (-1012) planes reported recently
[Zhang et al., Scr. Mater. 67 (2012) 862].
