The properties of carbon nanotubes can be dramatically altered by the presence of defects. In this work we address the properties of two different kinds of defective nanotubes: junctions of achiral tubes with topological defects and partially unzipped carbon nanotubes. In particular, we begin by focussing on the interface states in carbon nanotube junctions between achiral tubes. We show that t...

The interaction of the glycine radical on the side walls of both armchair and zigzag single walled carbon nanotubes is investigated by density functional theory. It is found that the interaction potential of the N-centered glycine radical with the tubes has a minimum of 16.9 (armchair) and 20.2 (zigzag) kcal/mol with respect to the dissociation products. In contrast, the C-centered radical, whi...

Unusual physical properties of single-wall carbon nanotubes have started a search for similar tubular structures of other elements. In this paper, we present a theoretical analysis of single-wall nanotubes of silicon and group-III-V compounds. Starting from precursor graphenelike structures we investigated the stability, energetics, and electronic structure of zigzag and armchair tubes using th...

We have studied the behavior of band gap and effective mass of both the electrons and the holes in small diameter zigzag single-walled carbon nanotubes under uniaxial mechanical strain by using first-principles density-functional theory. The band gap of these nanotubes is modified by both compressive and tensile strain and all zigzag single-wall carbon nanotubes show a semiconductor-metal trans...

Esterification of oxidized carbon nanotubes (CNTs) can open a new route for the separation of zigzag and armchair nanotubes. We studied theoretically (by using hybrid DFT within the ONIOM embedding protocol) the reactions of monocarboxy-substituted oxidized tips of zigzag and armchair single-walled CNTs (SWCNTs) with methanol. According to the calculated values of activation energy, Gibbs free-...

adsorption of co2 on the surface of single-wall zigzag (5,0) and armchair (4,4) carbon nanotubes (swcnts) were studied through using density functional theory (dft) calculations. optimizations of geometric were performed at the b3pw91 level of 6-311++g** method standard basis set using gaussian 03 package of program [1]. structural models were optimized and adsorption energies, band gap, charge...

the physical adsorption of hydrogen sulfide and carbon dioxide gases on the zigzag (5,0) carbon nanotubes doped with nitrogen was investigated through the application of b3lyp/6-31g* at the level of theory on gaussian 03 software. a variety of stable and high abundance structures of nitrogen doped carbon nanotubes were considered in order to study the interaction between the mentioned gases in ...

   In this study the adsorption of selenium molecule (Se2) on the outer surface of zigzag (5,0), (8,0) and (10,0) carbon nanotubes has been investigated. We examined number adsorbed orientations as well as different adsorption sites on nanotubes. The adsorption energies, equilibrium distances, energy differences between the highest occupied molecular orbital (HOMO) and lowest uno...

Using density-functional theory the stability of armchair and zigzag single-walled carbon nanotubes and graphene nanoribbons was investigated. We found that the stability of armchair and zigzag nanotubes has different linear dependence with regard to their length, with switches in the most stable chirality occurring at specific lengths for each nanotube series. We explain these dependencies by ...

Adsorption of CO2 on the surface of Single-wall zigzag (5,0) and armchair (4,4) carbon nanotubes (SWCNTs) were studied through using density functional theory (DFT) calculations. Optimizations of geometric were performed at the B3PW91 level of 6-311++G** method standard basis set using GAUSSIAN 03 package of program [1]. Structural models were optimized and adsorption energies, band gap, charge...