Softening Effect in Stretching Stiffness of a Rippled Graphene: Molecular Dynamics Simulation

In this paper, the stretching stiffness of a rippled graphene is studied using the molecular dynamics simulation. The uneven surface of the rippled graphene is modeled by a random function with different amplitudes and frequencies. Two models of the rippled graphene are simulated. In the first model, it is supposed that the graphene has random wrinkles with different amplitudes and frequencies. It can be regarded as an opened crumpled graphene. In the second model, the uneven surface of the rippled graphene is modeled by the trigonometric sine shapes. The adaptive intermolecular reactive bond order potential function is utilized to model the covalence bonding of the carbon atoms and the Nose-Hoover thermostat is used to control temperature of the system. It is implemented in the software package large scale atomic/molecular massively parallel simulator in order to simulate covalent bond formation between carbon atoms in the structure of graphene layer. Results are presented for both zigzag and armchair rippled graphene sheets with different initial surfaces. It is concluded that the failure strain of a rippled graphene under uniaxial tensile loading is less than that of a flat one. It is also demonstrated that the rippled graphene has softening stretching behavior due to its uneven surface.