Localized Gaussian Type Orbital−Periodic Boundary Condition−Density Functional Theory Study of Infinite-Length Single-Walled Carbon Nanotubes with Various Tubular Diameters

doi:10.1021/jp074107l

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Title:	Localized Gaussian Type Orbital−Periodic Boundary Condition−Density Functional Theory Study of Infinite-Length Single-Walled Carbon Nanotubes with Various Tubular Diameters
Authors:	Wang, Houng-Wei;Wang, Bo-Cheng;Chen, Wen-Hao;Hayashi, Michitoshi
Contributors:	淡江大學化學學系
Keywords:	Bond length;Boundary conditions;Density functional theory;Geometry;Optimization;Crystal orbitais;Tubular diameters;Single-walled carbon nanotubes (SWCN)
Date:	2008-02
Issue Date:	2013-06-13 11:24:20 (UTC+8)
Publisher:	Washington, DC: American Chemical Society
Abstract:	The detailed geometrical structures of zigzag and armchair type single-walled carbon nanotubes (SWCNTs) with infinite tubular length were investigated using localized Gaussian type orbital−periodic boundary condition−density functional theory (LGTO−PBC−DFT) method. The structures of (n, 0) zigzag SWCNTs were optimized for n = 5−21, (n, n) armchair SWCNTs for n = 3−12. For comparison, the optimized geometry of a two-dimensional graphite sheet was also calculated. It was found that the optimized structures of the SWCNTs showed two C−C bond lengths that decrease with an increase in the tubular diameter. More specifically, the two bond lengths converged with those found in the two-dimensional graphite sheet. We also found a degeneracy in the highest occupied crystal orbitals if identical bond lengths were employed for the zigzag SWCNTs and the two-dimensional graphite sheet. This implies that the two different bond lengths found in the zigzag SWCNTs and the two-dimensional graphite sheet are probably due to the Jahn−Teller effect. The armchair SWCNTs show two slightly different bond lengths if the diameter is less than 12 Å; otherwise they are almost identical, approaching the longer bond length of the two-dimensional graphite sheet. This can be due to the fact that the armchair SWCNTs do not have degeneracy in occupied crystal orbitals for identical C−C bond lengths. The crossing point of the conducting and valence bands of each armchair SWCNT were also calculated and show a diameter dependence in which the deviation from 2π/3a decreases as diameter increases.
Relation:	Journal of Physical Chemistry A 112(8), pp.1783-1790
DOI:	10.1021/jp074107l
Appears in Collections:	[Graduate Institute & Department of Chemistry] Journal Article

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