Theoretical investigation of electronic bandgaps of semiconducting single-walled carbon nanotubes using semi-empirical self-consistent tight binding and ab-inito density functional methods

ABSTRACTFundamentally new families of carbon single walled nanotubes are proposed. These nanotubes, called graphynes, result from the elongation of covalent interconnections of graphite-based nanotubes by the introduction of yne groups. Similarly to ordinary nanotubes, armchair, zig-zag, and chiral graphyne nanotubes are possible. We present here results for the electronic properties of graphyne based tubes obtained from tight-binding and ab initio density functional methods.

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Tight binding simulation study on zigzag single-walled carbon nanotubes

International Journal of Modern Physics B ◽

10.1142/s0217979218500200 ◽

2018 ◽

Vol 32 (03) ◽

pp. 1850020 ◽

Cited By ~ 1

Author(s):

Deepa Sharma ◽

Neena Jaggi ◽

Vishu Gupta

Keyword(s):

Carbon Nanotubes ◽

Density Functional ◽

Tight Binding ◽

Single Walled Carbon Nanotubes ◽

Finite Energy ◽

Model Parameters ◽

Simulation Studies ◽

Single Walled Carbon ◽

Mixing Method ◽

Walled Carbon Nanotubes

Tight binding simulation studies using the density functional tight binding (DFTB) model have been performed on various zigzag single-walled carbon-nanotubes (SWCNTs) to investigate their electronic properties using DFTB module of the Material Studio Software version 7.0. Various combinations of different eigen-solvers and charge mixing schemes available in the DFTB Module have been tried to chalk out the electronic structure. The analytically deduced values of the bandgap of (9, 0) SWCNT were compared with the experimentally determined value reported in the literature. On comparison, it was found that the tight binding approximations tend to drastically underestimate the bandgap values. However, the combination of Anderson charge mixing method with standard eigensolver when implemented using the smart algorithm was found to produce fairly close results. These optimized model parameters were then used to determine the band structures of various zigzag SWCNTs. (9, 0) Single-walled Nanotube which is extensively being used for sensing NH3, CH4 and NO2 has been picked up as a reference material since its experimental bandgap value has been reported in the literature. It has been found to exhibit a finite energy bandgap in contrast to its expected metallic nature. The study is of utmost significance as it not only probes and validates the simulation route for predicting suitable properties of nanomaterials but also throws light on the comparative efficacy of the different approximation and rationalization quantum mechanical techniques used in simulation studies. Such simulation studies if used intelligently prove to be immensely useful to the material scientists as they not only save time and effort but also pave the way to new experiments by making valuable predictions.

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Largest Band Gap of All Single Walled Carbon Nanotubes

MRS Proceedings ◽

10.1557/proc-772-m5.3 ◽

2003 ◽

Vol 772 ◽

Cited By ~ 2

Author(s):

I. Cabria ◽

J. W. Mintmire ◽

C. T. White

Keyword(s):

Carbon Nanotubes ◽

Band Gap ◽

Density Functional ◽

Local Density ◽

Tight Binding ◽

Single Walled Carbon Nanotubes ◽

Theoretical Work ◽

First Principles Calculations ◽

Single Walled Carbon ◽

Walled Carbon Nanotubes

AbstractSingle walled carbon nanotubes, SWNTs, are either semiconducting, metallic, or quasimetallic. Early theoretical work based on tight-binding models predicted that the band gap of semiconducting carbon nanotubes should increase with decreasing radius and this picture was later confirmed by experiment. However, local-density functional calculations indicate that these models are not accurate for narrow carbon nanotubes, where the effects of curvature can convert nanotubes expected to be semiconductors to metals. This raises the question, what is the largest semiconducting band gap possible in a SWNT? We present results from first-principles calculations for a range of carbon nanotubes with radii between 0.15 and 1 nm. These results indicate that the (4,3) carbon nanotube has the largest band gap of all SWNTs.

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