Implementing molecular dynamics on the IBM SP1 and PVS parallel computers, we have studied the fracture of two-dimensional notched solids under tension using ${10}^6$ atom systems. Many recent laboratory findings occur in our simulation experiments, one of the most intriguing being the dynamic instability of the crack tip as it approaches a fraction of the sound speed. A detailed comparison between laboratory and computer experiments is presented, and microscopic processes are identified. In particular, an explanation for the limiting velocity of the crack being significantly less than the theoretical limit is provided.

• Received 28 March 1994

DOI:https://doi.org/10.1103/PhysRevLett.73.272