Fracture paths and ultrananocrystalline diamond

We use the simulated fracture of ultrananocrystalline diamond (UNCD) to illustrate how different fracture paths can result in different predictions of system properties. At zero temperature, the system is unable to explore the potential energy surface far from the fracture path being investigated. This can result in misleading predictions for the mechanical properties of UNCD. In non-zero temperature simulations, the system can explore more of the potential energy surface, but these are computationally intense simulations. We show how lower bounds to the energy path during fracture can be determined in pure and nitrogen-doped UNCD without doing finite temperature simulations.