Minimum energy pathways of brittle and ductile deformation/fracture processes

An alternative approach to exploring deformation and fracture processes from molecular dynamics simulations is presented. The underlying concept is based on the transition path sampling scheme which was proven powerful for unprejudiced mechanistic analyses of rare reaction events and phase transitions. Transferring this method to deformation and fracture is particularly rewarding for the study of brittle materials. Similar to unbiased investigations of nucleation events in first order phase transitions, our simulations do not require the preparation of cavities to induce fracture processes. The mechanisms of cavitation and fracture propagation are instead obtained as simulation results. As two case studies, transition path sampling related to brittle fracture of ZnO nanorods and to ductile deformation of Al nanoblocks is compared to conventional simulations imposing constant-strain rates.