Search results for "Zigzag"

Evidence for Graphene Edges Beyond Zigzag and Armchair

2009

The edges of nanoscopic objects determine most of their properties. For this reason the edges of honeycomb carbon--always considered either zigzag- or armchair-like--need special attention. In this report we provide experimental evidence confirming a previous unexpected prediction: zigzag is a metastable edge, as its planar reconstruction lowers energy and forms the most stable graphene edge. Our evidence is based on re-analyzing a recent experiment. Since the reconstructed edge, along with other unconventional edges we discuss, has distinct chemical properties, this discovery urges for care in experiments and theory--we must enter the realm beyond zigzag and armchair.

Cover Picture: Cyanide-Bridged Iron(III)–Cobalt(II) Double Zigzag Ferromagnetic Chains: Two New Molecular Magnetic Nanowires (Angew. Chem. Int. Ed. 1…

2003

Solution and on-surface synthesis of structurally defined graphene nanoribbons as a new family of semiconductors.

2018

Graphene nanoribbons (GNRs) with various structures and properties can be synthesized in solution or on surface.

DFT studies of OH-functionalized open-ended zigzag, armchair, and chiral single wall carbon nanotubes

2011

The functionalization of single-wall carbon nanotubes (SWCNTs) by attaching various molecules or molecular groups to the exterior walls or tips has attracted much attention, because it offers a possible way to modify their electronic, chemical, optical and mechanical properties. In this contribution the results of DFT studies of pristine and OH-modified open-ended zigzag (9,0), armchair (5,5) and chiral (8,2) nanotubes are reported. The calculations have been performed for partially and fully functionalized at one end model SWCNTs with dangling bonds saturated with hydrogen atoms and a nonadditive dependence of attachment energy on the number of substituents was observed.

Self-Passivating Edge Reconstructions of Graphene

2008

Planar reconstruction patterns at the zigzag and armchair edges of graphene were investigated with density functional theory. It was unexpectedly found that the zigzag edge is metastable and a planar reconstruction spontaneously takes place at room temperature. The reconstruction changes electronic structure and self-passivates the edge with respect to adsorption of atomic hydrogen from molecular atmosphere.

Cyanide-bridged iron(III)-cobalt(II) double zigzag ferromagnetic chains: two new molecular magnetic nanowires.

2003

and opened the perspective of a potential useof 1D magnetic molecular nanowires for information storage.Even though 1D magnetism is a very active area of research,such dynamic behavior was never detected before since it isnot clear how to fulfill experimentally the requirements of aperfect 1D Ising-type chain. This finding prompted us to lookcarefully at 1D systems containing anisotropic elements,suchas cobalt(ii) and low-spin iron(iii) centers that we synthesizedrecently,

Effect of type, size and deformation on the polarizability of carbon nanotubes from atomic increments

2006

The interacting induced dipole polarization model is used for the calculation of the dipole–dipole polarizability α. The method is tested with single-wall carbon nanotubes (SWNTs) as a function of nanotube radius and elliptical deformation. The results are similar to ab initio reference calculations. For the zigzag tubes, the polarizability follows a remarkably simple law. The calculations effectively differentiate among SWNTs with increasing radial deformations. The polarizability and related properties can be modified continuously and reversibly by the external radial deformation. These results suggest a technology in which mechanical deformation can control chemical properties of the car…

DFT calculations of structures, 13C NMR chemical shifts and Raman RBM mode of simple models of ultra small diameter (4,0) zigzag hydroxylated single …

2012

Abstract Selected acenes, cyclic acenes and model zigzag (4,0) single wall carbon nanotubes (SWCNTs) with one hydroxylic group at the open end were fully optimized at the B3LYP/6-31G* level of theory. The impact of molecule size on the B3LYP/pcS-2 calculated 13 C NMR chemical shifts was studied to characterize pristine and tip-monofunctionalized ultra narrow SWCNTs. The harmonic frequency of Raman radial breathing mode (RBM) was determined for monohydroxylated cyclic acenes and correlated with their diameter. A regular convergence of selected CC bond lengths, RBM frequency and carbon chemical shifts upon increasing the size of the systems was observed and fitted toward very large systems wi…

Electronic properties of carbon nanotubes under torsion

2012

A computationally-effective approach for calculating the electromechanical behavior of SWNTs and MWNTs of the dimensions used in nano-electronic devices has been developed. It is a mixed finite element-tight-binding code carefully designed to realize significant time saving in calculating deformation-induced changes in electrical transport properties of the nanotubes. The effect of the MWNT diameter and chirality on the conductance after mechanical deformation was investigated. In case of torsional deformation results revealed the conductance of MWNTs to depend strongly on the diameter, since bigger MWNTs reach much earlier the buckling load under torsion their electrical conductivity chang…

Limits of stability in supported graphene nanoribbons subject to bending

2016

Graphene nanoribbons are prone to in-plane bending even when supported on flat substrates. However, the amount of bending that ribbons can stably withstand remains poorly known. Here, by using molecular dynamics simulations, we study the stability limits of 0.5-1.9 nm wide armchair and zigzag graphene nanoribbons subject to bending. We observe that the limits for maximum stable curvatures are below ~10 deg/nm, in case the bending is externally forced and the limit is caused by buckling instability. Furthermore, it turns out that the limits for maximum stable curvatures are also below ~10 deg/nm, in case the bending is not forced and the limit arises only from the corrugated potential energy…