Vibrational spectra of multishell fullerenes

We calculate the equilibrium structure of spherical multishell fullerenes and the low-frequency rattling modes of the nested shells. The pairwise nature of the intershell interactions allows us to topologically map these zero-dimensional systems onto a linear chain of fullerene shells. Even though the masses of the inidividual shells and the intershell interactions depend strongly on the shell number, the vibrational density of states of very large structures resembles closely that of an infinite linear chain with site-independent masses and force constants and a very low Debye frequency of 80.2 cm^-1.