The mechanical properties of three types of carbon allotropes

The mechanical properties of supergraphene, cyclicgraphene and graphyne are studied using molecular dynamics simulations based on the AIREBO potential. In particular, we present the chirality-dependence of their mechanical properties, including Young's moduli, shear moduli, Poisson's ratios, ultimate strength and ultimate strains. The relationship of their Young moduli, shear moduli and Poisson ratios is in the order of Y_su (super) < Y_cy (cyclic) < Y_gy (graphyne) < Y_ge (graphene), G _su < G_cy < G_gy < G_ge and v_su > v_cy > v_gy > v_ge in corresponding zigzag and armchair sheets, respectively. Their intersheet adhesion energy is obtained as γ_su = 30, γ_cy = 99 and γ_gy = 149 mJ m^-2, which are much lower than that of γ_ge = 291 mJ m^-2 (the value is in good agreement with the latest experimental result γ_ge = 310 ± 30 mJ m^-2). The obtained adhesion energy is accurately characterized by continuum modeling of the van der Waals interactions. Our study is very useful for the future applications of graphene-like materials in nanoelectromechanical systems.