Dynamical properties and related optical spectra of fullerenes: The bond-charge-model description

We present a study of the Raman and IR spectra of the ${\mathit{sp}}^2$-bonded carbon clusters ${\mathrm{C}}_{60}$ and ${\mathrm{C}}_{70}$, performed in the framework of a three-parameter bond-charge model based on a transferable interatomic potential. A consistent calculation of the relative amplitudes and of the static polarizability has been performed with only one additional parameter besides those entering the dynamics. The calculated spectra are compared with the existing experimental data for ${\mathrm{C}}_{60}$ and ${\mathrm{C}}_{70}$. Very good agreement is found for the Raman spectrum of both clusters, whereas the agreement for IR spectra is less satisfactory.