The lowering of the total energy due to the electron-vibration interaction is calculated for C60n- molecules and the electron-vibration contribution to the on-site interaction is obtained. It is found that C60n- is in the intermediate to strong-coupling limit, and that the vibration contribution to the on-site interaction is of the order -0.1 to -0.2 eV for n=1 and 3 and of the order +0.3 eV for n=2 and 4.
 

Physical Review B, 51 3493-7, 1995.