Stress-induced failure and melting of ideal solids

In order to investigate the failure of ideal solids, we perform molecular dynamics simulations of a three-dimensional defect-free crystal under uniaxial applied force/strain, using a semi-empirical many-body potential, under conditions of fixed temperature and pressure. We use a hybrid molecular dynamics/Monte Carlo computation technique that allows the periodic-boundary-condition cell to change both its shape and volume. We investigate the role of loading (or strain) rate as well as of low and high temperature. Under low temperature and slow loading conditions, we find that failure is sometimes preceded by a crystal–crystal phase transition that corresponds to a physically allowed lattice invariant (PALI) strain. At sufficiently high temperatures we observe direct failure of the system via stress-induced melting.