by employing the theoretical method based on tight-binding, we study electronic band structure of single-wall carbon nanotube (cnt) superlattices, which the system is the made of the junction between the zigzag and armchair carbon nanotubes. exactly at the place of connection, it is appeared the pentagon–heptagon pairs as topological defect in carbon hexagonal network. the calculations are base...

By employing the theoretical method based on tight-binding, we study electronic band structure of single-wall carbon nanotube (CNT) superlattices, which the system is the made of the junction between the zigzag and armchair carbon nanotubes. Exactly at the place of connection, it is appeared the pentagon–heptagon pairs as topological defect in carbon hexagonal network. The calculations are base...

By employing the theoretical method based on tight-binding, we study electronic band structure of single-wall carbon nanotube (CNT) superlattices, which the system is the made of the junction between the zigzag and armchair carbon nanotubes. Exactly at the place of connection, it is appeared the pentagon–heptagon pairs as topological defect in carbon hexagonal network. The calculations are base...

All self-assembled nanostructures, like carbon nanotubes, exhibit structural imperfections that affect their electronic and mechanical properties and constitute a serious problem for the development of novel electronic nanodevices. Very common defects in nanotubes are pentagon-heptagon pairs, in which the replacement of four hexagons by two pentagons and two heptagons disrupts the perfect hexag...

• Nanoribbon used to model semi-infinite graphene should consist of at least 6 rows. Distance between periodic images defects exceed lattice constants. The barrier 1.6 eV be passed start zigzag edge reconstruction. Atoms in isolated pentagon-heptagon pairs have small but nonzero magnetic moments. Spin ordering nanoribbon edges becomes parallel for large defect density. We investigate how parame...

Several paired, localized gap states were observed in semiconducting single-wall carbon nanotubes using spatially resolved scanning tunneling spectroscopy. A pair of gap states is found far from the band edges, forming deep levels, while the other pair is located near the band edges, forming shallow levels. With the help of a first-principles study, the former is explained by a vacancy-adatom c...

We investigate the electronic structure induced by wedge disclinations (conical singularities) in a honeycomb lattice model realizing Chern numbers γ = ± 1. We establish a correspondence between the bound state of (i) an isolated Φ(0)/2 flux, (ii) an isolated pentagon (n = 1) or heptagon (n = -1) defect with an external flux of magnitude nγΦ(0)/4 through the center, and (iii) an isolated square...

A carbon heptagon ring is a key unit responsible for structural defects in sp(2)-hybrized carbon allotropes including fullerenes, carbon nanotubes and graphenes, with consequential influences on their mechanical, electronic and magnetic properties. Previous evidence concerning the existence of heptagons in fullerenes has been obtained only in off-line halogenation experiments through top-down d...

We investigate energetics and structure of circular and polygonal single wall carbon nanotubes (SWNTs) using large scale molecular simulations on NAS SP2, motivated by their unusual electronic and magnetic properties. The circular tori are formed by bending tube (n, n) whereas the polygonal tori are constructed by turning the joint of two tubes of (n, n), (n+1, n-1) and (n+2, n-2) with topologi...

The complete symmetric directed graph of order $v$, denoted by $K_{v}$, is the on $v$~vertices that contains both arcs $(x,y)$ and $(y,x)$ for each pair distinct vertices $x$ and~$y$. For a given $D$, set all $v$ which $K_{v}$ admits $D$-decomposition called spectrum of~$D$-decomposition. There are 10 nonisomorphic orientations $7$-cycle (heptagon). In this paper, we completely settled problem ...