Elastic and non-linear stiffness of graphene: a simple approach

The recent experiment [Science $\mathbf{\text{321}}$, 385 (2008)] on the Young’s modulus and third-order elastic stiffness of graphene are well explained in a very simple approach, where the graphene is described by a simplified system and the force constant for the non-linear interaction is estimated from the Tersoff-Brenner potential.