Effect of geometrical defects on the tensile properties of graphene

The tensile properties of graphene with the Stone-Wales (S–W) defect are investigated by first principle calculations. It is found that the defect will not affect the elastic modulus and Poisson's ratio of graphene but causes the pre-stress of graphene, which makes the graphene to be anisotropic: the deformation along one direction is much easier than that along another direction. The pre-stress field causes only about 10% decrease of the intrinsic stress of graphene but causes more than 50% decrease of the maximum failure strain, which is significantly different with the results calculated by the empirical potential. The main reason is that the pre-stress field created by the S–W defect predicted by first principle calculations is different than that calculated from molecular mechanics simulations. In addition, it is also found that the theoretical solution (on the basis of the continuum disclination dipoles model) of the pre-stress field created by the S–W defect is also different with that determined from MM simulations, which is different from the results of the aligned 7-5 defects of graphene.