Molecular Dynamics simulations of crack propagation mode in silica

Using Molecular Dynamics simulations, we investigate the initiation and the propagation of a crack at the atomic scale in beta-cristobalite and in amorphous silica. It was found that in the crystal the crack propagates by decohesion whereas in the amorphous the crack propagates by growth and coalescence of cavities like in ductile materials. These different behaviors find their origin in the differences of the two structures.