Analytical derivation of electronic band gap of Single Walled Carbon Nanotube (SWCNT) under a small percent of uniaxial and torsional strains is in this paper. Our approach is based on a kind of π-Tight Binding (π-TB) approximation which includes interactions of the second and the third neighbors of each carbon atom in addition to the nearest ones. Implementing the approach of this paper, yields more precise results than those of other researches.
Abstract:In this paper we use symmetry of Single Walled Carbon Nanotubes (SWCNTs) to generate some types of virtual sub-bands that are lower in number than the real sub-bands obtained through conventional -TB. It is shown that the virtual sub-bands maintain the value of band gap. In obtaining the sub bands, the interactions of the nearest and the second and third-nearest neighbors are taken into account. As the consequence of lower number of sub-bands, a significant reduction in computational effort has occurred and made the approach useful.
PACS (2008):71.15. Ap, 71.20.Tx,
Abstract-In this paper we investigate the effect of uniaxial and torsional strains on the Density of States (DOS) of single walled Carbon nanotubes (SWCNTs). We employ the nearest neighbor and the third nearest neighbor π-TB (Tight Binding) models for our investigation. It is shown that uniaxial and torsional strains in some cases of metallic SWCNTs not only open a band gap but also effectively increase the DOS of SWCNT. It is also shown that, the mentioned types of strain have different effects on the DOS of chiral SWCNTs; in some types, they increase the DOS at the band edges while in other types they decrease it at the band edges.
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