NEUTRON-SCATTERING STUDY OF THE INTERMOLECULAR VIBRATIONS IN SOLID C-60

We present a detailed account of an inelastic neutron scattering study of the intermolecular vibrations in solid C-60 above and below the st ructural phase transformation. Assignment of the observed phonon peaks to modes of translational and librational character is discussed on t he basis of lattice dynamical calculations using phenomenological inte rmolecular potentials. A new bond charge model is presented which repr oduces the observed phonon branches very well. However, the apparently small influence of the orientational disorder on the librational exci tations remains to be understood.