Empirical prediction of optical transitions in metallic armchair SWCNTs

In this work, a quick and effective method to calculate the second and third optical transition energies of metallic armchair single wall carbon nanotubes (SWCNT) is presented. In this proposed method, the transition energy of any armchair SWCNT can be predicted directly just by knowing one of its chiral index. The predicted results are compared with recent experimental data and found to be accurate over a wide diameter range. The empirical equation proposed here is also compared with that proposed in earlier works. The proposed way may help the research works or applications where information of optical transitions of armchair metallic nanotubes is needed.