Quantum-mechanics/Molecular-mechanics (QM/MM) Simulations for Fracture from Dislocation Cores in SrTiO₃

Abstract

Dislocations, a lattice defect in crystals, have been believed to play an important role in determining plastic behavior of materials due to their mobility. Recently, a new role of dislocations as an initiation of brittle fracture was suggested by experiments. Here, we demonstrate fracture phenomena from dislocation cores and the mechanics using quantum-mechanics/molecular-mechanics (QM/MM) simulations. Our QM/MM simulations successfully reproduce fracture stress/strain and fracture morphology obtained by experiments. We also find that sequential local bond breaking of dislocation cores with loading is an origin of brittle fracture of dislocation. Therefore, we provides an insight into the new role of dislocations in crystals.