“…A more refined theory of dislocation nucleation based on the Peierls-Nabarro model (Peierls, 1940;Nabarro, 1952) was later proposed by Rice (1992). Subsequent experimental findings (Jokl et al, 1989;Huang and Gerberich, 1992;Zielinski et al, 1992;Marsh et al, 1992;George and Michot, 1993) and recent results of large scale atomistic simulations (Grujicic and Du, 1995;Cleri et al, 1997;Zhou et al, 1997;Bulatov et al, 1998;Cleri et al, 1998;Farkas, 1998;Waghmare et al, 2000;Farkas, 2000;Farkas et al, 2001;Bernstein and Hess, 2003;Guo et al, 2003;Mattoni et al, 2005;Farkas, 2005) have suggested that the fracture of brittle materials is a multiscale phenomenon involving cleavage, dislocation emission, and a host of grain and grain boundary dependent mechanisms such as twinning, recrystallization, or phase transformation. Today, it has become a general consensus that fracture is an archetype of multiscale phenomena in condensed solid state physics.…”