Semiempirical quantum-chemical assignment of the circular dichroism spectra of small chiral fullerenes Original Research Article

The semiempirical quantum-chemical simulation of the circular dichroism, CD, spectra of the lowest chiral fullerenes allows matching of an enantiomer and its spectrum. Comparison of calculations and experimental spectra for C78 and C84 makes it possible to establish that the CNDO/S method (Complete Neglect of Differential Overlap/Spectroscopic parameterization) is well suited to model the electronic CD response of fullerenes up to 400–500 nm. Two isomers of C82, for which no experimental spectra are as yet available, are added. The linewidth of the CD spectra of C78 and C84 is simulated through two quantities: the first is the density of vibrational states of the electronic ground state and partly accounts for the non-radiative lifetime of the excited states that decreases with the increase of the excitation energy; the second is the Stokes shift of the individual electronic states and accounts for the vibronic broadening.