Contribution analysis of the van der Waals term on electronic structures of carbon related systems

Contribution of the van der Waals term in the electron densities and the band structures of covalent bonding one-dimensional networks are studied. Calculations are performed with self-consistently implemented nonlocal van der Waals density functional (vdW-DF) into a first principle program. Results indicate that the contribution of the van der Waals term on band structures qualitatively depends on the bonding types, whether π orbitals are included or not in calculated systems.