Extended tight-binding potential for modelling intertube interactions in carbon nanotubes

Due to the intrinsic connection between the mechanical properties of carbon nanotubes and their long-ranged interactions, an accurate description for both covalent and van der Waals forces is desired in nanomechanical studies. A tight-binding treatment offers an accurate description for the covalent bonding but fails to account for the long-ranged attractions and for the energy variations of graphite layers under relative shift. Combining the most reliable experimental data on graphite (equilibrium interlayer spacing, Z-axis compressibility, and the interlayer shear-mode frequency), tight-binding is extended to model the interlayer interactions of graphitic structures.