Ab-initio study of electronic properties of a two-dimensional array of carbon nanotubes

The equilibrium geometry and electronic band structure of a planar array of carbon nanotubes are studied with the use of the Quantum Espresso code - a plane-wave realisation of the density functional theory (DFT). The many-electron correlations and van der Waals corrections are taken into account. The optimal distance between nanotubes in the array corresponding to the minimum of the total energy of the system is found. A strongly anisotropic hyperbolic dispersion is demonstrated for low-energy charge carriers in an array of quasi-metallic (15,0) carbon nanotubes with the optimal inter-tube separation governed by van der Waals forces.