Abstract

Changes in the band structure of carbon nanotubes induced by twisting of the tubes around their axes are studied by quantum-chemical methods, namely, the symmetrized augmented cylindrical waves ab initio method. The effects of torsional modes on the electronic properties of achiral and chiral, semiconducting, metal, and quasi-metal nanotubes are calculated. It is found that, due to the intersection of dispersion curves, twisting of chiral tubes leads to complex dependences of the optical gap on the torsional mode amplitude. In zigzag-type achiral semiconductor tubes, the band structure and band gaps are stable toward torsional modes. In armchair tubes twisting leads to the rapid formation and increase of the band gap. In chiral and achiral, metallic and quasi-metallic nanotubes, the optical gap increases independently of the tube twisting direction, while in semiconductor nanotubes, it depends thereon. Our results can be used for the design of elements of nanoelectromechanical carbon nanotube systems.

中文翻译：

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根据圆柱波法扭转应变对碳纳米管能带结构的影响

摘要

通过量子化学方法，即从头计算对称增强圆柱波方法，研究了由管绕其轴扭转引起的碳纳米管能带结构的变化。计算了扭转模式对非手性和手性、半导体、金属和准金属纳米管的电子特性的影响。发现，由于色散曲线的交叉，手征管的扭曲导致光学间隙对扭转模式幅度的复杂依赖性。在锯齿形非手性半导体管中，带结构和带隙对扭转模式是稳定的。在扶手椅中，管子扭曲会导致带隙的快速形成和增加。在手性和非手性、金属和准金属纳米管中，光学间隙的增加与管扭曲方向无关，而在半导体纳米管中，则取决于此。我们的结果可用于设计纳米机电碳纳米管系统的元件。