Calculating optical transition energies in semiconducting zigzag SWCNTs

Zigzag carbon nanotubes possess special structural symmetry and some unique characteristics among three categories of single wall carbon nanotubes (SWCNTs). In this work, a quick method to calculate the first five optical transition energies of semiconducting zigzag and nearly zigzag SWCNTs is presented. Using the proposed method, the transition energy of any semiconducting zigzag and nearly zigzag SWCNT can be predicted directly just by knowing its first chiral index. The predicted results are compared with recent experimental data and found to be accurate over a wide diameter range. The proposed method can help finding the relation between geometric structure and optical properties of zigzag SWCNTs. It is also helpful for the applications of SWCNTs where information of optical transitions of a semiconducting zigzag nanotubes is needed.