On the vibrational modes of C60

The vibrational spectrum of C60 is compared to the spectrum of a classical isotropic elastic spherical shell. We show correlations between the low frequency modes of C60 and those of the spherical shell. We find the spherical model gives the approximate frequency ordering for the low frequency modes. We estimate a Poisson ratio of σ ≈ 0.30 and a transverse speed of sound of υs ≈ 1800 m/s for the equivalent elastic shell. We also find that ω(M1)ω(M0) = √32 for the shell modes M0 and M1, independent of elastic constants. We find that this ratio compares favorably with an experimental value of 1.17.