A Density Functional Theory Study of the Mechanical Properties of Graphane With van der Waals Corrections

We investigate the mechanical properties of graphane using first-principles calculations based on density functional theory (DFT) with van der Waals (vdW) interactions in DFT-D2 approach. The mechanical stability of graphane was tested with three deformation modes-armchair, zigzag, and biaxial. We find that it is safe to neglect vdW because it has little effect on the geometry (<0.4%) and the mechanical properties, including ultimate stresses (2%), ultimate strains (8.7%), in-plane stiffness (1%), and Poisson ratio (3%). Our result is helpful to estimate the effect of vdW on the mechanical properties of chemically functionalized graphane systems.