为了探索X型碳纳米管的介电性质和可见光吸收性质,建立了手性矢量分别为(5,5)和(8,0)的碳纳米管交合的X型碳纳米管模型。采用基于密度泛函的平面波赝势法对其进行几何结构优化和光学性质探索,运用广义梯度近似理论超软赝势对交换相关能进行近似。计算结果表明被交合而成的碳纳米管的介电常数曲线和可见光吸收曲线的峰值大小和峰值位置均发生了变化,这是因为碳纳米管结构的变化导致碳原子间的能级发生改变,从而改变了光子跃迁能量和吸收光子的波长。

An X-typed carbon nanotube is built by welding carbon nanotube (5, 5) and carbon nanotube (8, 0) in order to calculate dielectric constant and absorption. The geometric structure and optical properties of X-typed carbon nanotube are investigated by using the plane-wave pseudo-potential method, with the scheme of generalized gradient approximation revised Perdew-Burke-Emzerhof exchange-correlation potential and ultra-soft pseudo potential based on density function theory. Compared to the carbon nanotube (5, 5) and carbon nanotube (8, 0), the value and frequency of absorption peak and X-typed carbon nanotube is different, because distance between each atoms is changed and energy gap is changed which makes photons with different frequency absorption change.