In this theoretical study, within the nearest neighbor tight-binding model, the density of states (DOS), Pauli magnetic susceptibility (PMS), and electronic heat capacity (EHC) of graphyne-like systems, i.e. α-, β-, γ-,
-graphyne, and graphdiyne are calculated and the results are compared with that of a graphene monolayer. It is observed that α-, β- and
-graphyne are semimetals with a zero bandgap similar to a graphene monolayer, while γ-graphyne and graphdiyne have no states around the Fermi level. In addition, the intra-bandgaps are seen in the DOS of graphyne structures and the van-Hove singularities in the DOS of all systems. These lead to the crossovers occurred in the PMS curves and the Schottky anomaly peaks in the EHC curves, which are divided into two low and high temperature regions. Also, it is found that close to the temperature of zero, the PMS and EHC of all semimetal systems are slightly higher than semiconducting systems. From the theoretical stand point, this phenomenon stems from the proportional relation of the PMS and EHC with DOS.
By using ab initio density functional theory we investigated the structural and electronic properties of semiconducting (9, 0), zinc oxide zigzag nanotube (ZnOZNT) bundle. The energetic and electronic evolutions of nanotubes in the bundling process are also studied. The effects of inter-tube coupling on the electronic dispersions of ZnONT bundle are demonstrated. Our results show that the inter-tube coupling leads to disappearance of the energy gap in semiconducting nanotube. We found that (9, 0) zigzag nanotube bundle has a metallic behavior.Keywords: Zinc oxide nanotube bundle; density functional theory; band structure. PACS Number(s): 71.15.Mb, 73.22.-f 2997 Mod. Phys. Lett. B 2010.24:2997-3003. Downloaded from www.worldscientific.com by MCGILL UNIVERSITY on 02/19/15. For personal use only.
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