Role of grain orientation mismatch in friction of graphene layers using the Lennard-Jones and DRIP potentials

Graphene, as a one-atom thick 2-D material, is an ideal solid lubricant for small length scale devices such as micro/electro-mechanical systems. Without an accurate interatomic potential, the friction property of graphene is difficult to predict properly. In this study, two interatomic potentials, Lennard-Jones (LJ) and dihedral-angle-corrected registry-dependent interlayer (DRIP), are used to model interlayer interactions in friction simulations of multilayer graphene models. Both potentials have similar attractive interactions, but the DRIP potential considers the dihedral angle as well as the bond distance to model the repulsive interaction. We investigate the friction properties between a pristine layer and a single grain layer with different orientation angles using molecular dynamics (MD) simulations. The simulation results reveal that the LJ potential shows an increase in friction at misorientation angle of about 0.3° compared to a model with an angle of 0°. On the contrary, the DRIP models exhibit a monotonous decrease with increasing misorientation angle, which is attributed by the change in potential energy surface due to the dihedral angle.