Caetano E W S, Freire V N, dos Santos S G, Albuquerque E L, Galvão D S, Sato F
Centro Federal de Educação Tecnológica do Ceará, Avenida 13 de Maio, 2081, Benfica, 60040-531 Fortaleza, Ceará, Brazil.
Langmuir. 2009 Apr 21;25(8):4751-9. doi: 10.1021/la803929f.
We present some computational simulations of graphene-based nanoribbons with a number of half-twists varying from 0 to 4 and two types of defects obtained by removing a single carbon atom from two different sites. Optimized geometries are found by using a mix of classical quantum semiempirical computations. According with the simulations results, the local curvature of the nanoribbons increases at the defect sites, especially for a higher number of half-twists. The HOMO-LUMO energy gap of the nanostructures has significant variation when the number of half-twists increases for the defective nanoribbons. At the quantum semiempirical level, the first optically active transitions and oscillator strengths are calculated using the full configuration interaction (CI) framework, and the optical absorption in the UV/vis range (electronic transitions) and in the infrared (vibrational transitions) are achieved. Distinct nanoribbons show unique spectral signatures in the UV/vis range, with the first absorption peaks in wavelengths ranging from the orange to the violet. Strong absorption is observed in the ultraviolet region, although differences in their infrared spectra are hardly discernible.
我们展示了一些基于石墨烯的纳米带的计算模拟，这些纳米带具有从0到4不等的多个半扭转，以及通过从两个不同位点去除单个碳原子而获得的两种类型的缺陷。通过使用经典量子半经验计算的组合来找到优化的几何结构。根据模拟结果，纳米带的局部曲率在缺陷位点处增加，特别是对于较多数量的半扭转。当有缺陷的纳米带的半扭转数量增加时，纳米结构的HOMO-LUMO能隙有显著变化。在量子半经验水平上，使用完全组态相互作用（CI）框架计算了第一光学活性跃迁和振子强度，并实现了紫外/可见范围（电子跃迁）和红外（振动跃迁）的光吸收。不同的纳米带在紫外/可见范围内显示出独特的光谱特征，其第一个吸收峰的波长范围从橙色到紫色。在紫外区域观察到强吸收，尽管它们的红外光谱差异很难辨别。
