|10-056||Walter Kob||Kob, W.(University of Montpellier); Zhang, Z.(University of Montpellier); Ispas, S.(University of Montpellier);||Although understanding the process of fracture is important for many applications, rather little is known on it on the microscopic level. For example the role of the network modifiers on the fracture dynamics is not clear since on one hand they can locally weaken the glass, on the other hand also increase the overall stiffness of the sample. In this talk I will present some recent results of large scale computer simulations in which we have investigated the fracture behavior of sodium-silicate glasses. For weak sodium content we find that the presence of a scratch on the surface will strongly affect the fracture toughness, whereas glasses with high sodium content have a fracture behavior that is less influenced to such surface defects. Furthermore we have studied how the sodium content affects the propagation of the fracture front and how it influences the so produced glass surfaces.