Annihilation process of a diagonally arranged dislocation pair in graphene: density-functional tight-binding molecular dynamics and first-principles studies

The annihilation process of a dislocation pair in graphene is investigated using quantum mechanical molecular dynamics simulations based on the density-functional tight-binding method. First-principles calculations are performed to analyze the energetics, bonding states, and reaction pathways of key structures. The results demonstrate that local distortion of the graphene lattice originating from thermal disorder can induce primary chemical events, such as bond rotation and C 2 elimination, through close proximity of the second-nearest-neighbor atoms to each other. This process results in the formation and migration of 5–7 pairs. The final intermediates before complete dislocation annihilation tend to be two 5–7 pairs fused together. These intermediates include the Stone–Wales and inverse Stone–Wales defects, as well as an assembly of two head-to-head 5–7 pairs. Furthermore, graphene containing a pair of dislocations switches between antisymmetric forms with respect to out-of-plane deformation via a symmetric intermediate form. These findings are expected to contribute to the development of defect engineering in graphene-based nanomaterials. • Annihilation of dislocation pairs in graphene was achieved in DFTB/MD simulations. • Lattice deformation can induce bond rotation and C 2 evaporation in defective graphene. • The final intermediate before annihilation is a single inverse Stone–Wales defect. • The intermediate region of a diagonal dislocation pair configuration is highly intact. • The out-of-plane symmetric form mediates switching motion between antisymmetric forms.