Excitations, optical absorption spectra, and optical excitonic gaps of heterofullerenes. I. C ₆₀, C ₅₉N ⁺, and C ₄₈N ₁₂: Theory and experiment

The low-energy excitations and optical absorption spectrum of C ₆₀ were investigated using time-dependent density functional theory (TD-DFT). The method uses a minimum basis set and does not employ any empirical parameter. It was found that for accurately assigning the spectral features of C ₆₀, electron correlations and correlation of excitation play important roles. The results show that TD-DFT-TB is useful for studying the optical properties of heterofullerenes with organic molecules, (hetero)fullerene clusters and carbon nanotubes, which have the potential in optoelectronics and for predicting the optical gaps of large nanocrystals.