  Understanding, predicting and eventually improving the resistance to fracture
of silicate materials is of primary importance to design new glasses that would
be tougher, while retaining their transparency. However, the atomic mechanism
of the fracture in amorphous silicate materials is still a topic of debate. In
particular, there is some controversy about the existence of ductility at the
nano-scale during the crack propagation. Here, we present simulations of the
fracture of three archetypical silicate glasses using molecular dynamics. We
show that the methodology that is used provide realistic values of fracture
energy and toughness. In addition, the simulations clearly suggest that
silicate glasses can show different degrees of ductility, depending on their
composition.
