Lattice dynamics of the fullerenesMxC60

Abstract

Lattice dynamical calculations of the phonon density of states of external modes are reported for ${\mathrm{K}}_{3}{\mathrm{C}}_{60},$ ${\mathrm{Rb}}_{3}{\mathrm{C}}_{60},$ and ${\mathrm{Rb}}_{6}{\mathrm{C}}_{60}$ using three different models of transferable interatomic potentials. On comparison with the experimental reported data, an interatomic potential consisting of Coulomb and short range interactions has been found most suitable to explain the phonon density of states of the systems studied. Calculations using the rigid molecular ion model have enabled assignment of various important features in the experimental phonon spectra in terms of the vibrations of different species.