Normal modes of vibration of the C-60 isotopomers C-12(59) C-13 and C-12(58) C-13(2)

The vibrational excitation spectra of the isotopomers (C59C)-C-12-C-13 and (C58C2)-C-12-C-13 has been calculated within the framework of a first principle calculation. The force constants between the carbon atoms we obtained by performing the second derivatives of the energy within the Hartree-Fock approximation. A comparison of the frequency shifts in the vibrational spectra produced by the isotopes with Raman spectroscopy experiments is also presented. (C) 2000 American Institute of Physics. [S0021-9606(00)00527-4]