This paper applies a symmetry-adapted method to examine the influence of deformation and defects on the electronic structure and band structure in carbon nanotubes. First, the symmetry-adapted approach is used to develop the analog of Bloch waves. Building on this, the technique of perfectly-matched layers is applied to develop a method to truncate the computational domain of electronic structure calculations without spurious size effects. This provides an efficient and accurate numerical approach to compute the electronic structure and electromechanics of defects in nanotubes. The computational method is applied to study the effect of twist, stretch, and bending, with and without various types of defects, on the band structure of nanotubes. Specifically, the effect of stretch and twist on band structure in defect-free conducting and semiconducting nanotubes is examined, and the interaction with vacancy defects is elucidated. Next, the effect of localized bending or kinking on the electronic structure is studied. Finally, the paper examines the effect of 5-8-5 Stone-Wales defects. In all of these settings, the perfectly-matched layer method enables the calculation of localized non-propagating defect modes with energies in the bandgap of the defect-free nanotube.

中文翻译：

---

具有缺陷、扭结、扭曲和拉伸的碳纳米管的对称适应紧束缚电子结构分析

本文采用对称适应方法研究变形和缺陷对碳纳米管中电子结构和能带结构的影响。首先，对称适应方法用于开发布洛赫波的模拟。在此基础上，应用完美匹配层的技术开发了一种方法，可以在没有虚假尺寸效应的情况下截断电子结构计算的计算域。这为计算纳米管缺陷的电子结构和机电提供了一种有效且准确的数值方法。计算方法用于研究扭曲、拉伸和弯曲，有和没有各种类型的缺陷，对纳米管能带结构的影响。具体来说，研究了拉伸和扭曲对无缺陷导电和半导体纳米管中能带结构的影响，并阐明了与空位缺陷的相互作用。接下来，研究了局部弯曲或扭结对电子结构的影响。最后，论文检验了 5-8-5 Stone-Wales 缺陷的影响。在所有这些设置中，完美匹配层法能够计算具有无缺陷纳米管带隙能量的局部非传播缺陷模式。