We present a study of the charge-induced vibrational frequency shifts of the Raman active modes in the ${\mathrm{C}}_{60}^{\mathit{n}\mathrm{-}}$ molecules performed in the framework of a four-parameter transferable bond-charge model. The calculated relative shifts compare quite well with the existing experimental data and the residual discrepancies are in reasonable agreement with the vibronic shifts as given by ab initio calculations. For the half-filled conduction electronic shell (${\mathrm{C}}_{60}^{3\mathrm{-}}$ configuration), the dominant contribution to the electron-phonon coupling constant is seen to arise from low-frequency ${\mathit{H}}_{\mathit{g}}$ modes.

• Received 1 July 1994

DOI:https://doi.org/10.1103/PhysRevB.50.15439