The van der Waals Potential and the Phonon Dispersions in fcc Solid C60

Abstract

Based on the cohesive energy per molecule in fcc solid C60, the van der Waals potential is obtained by the use of the Möbius transform formula. It is found that the calculated van der Waals potential can be fitted by a Morse potential with proper parameters. Different from the previous works, this potential is free from any adjustable parameter, and by the use of the potential, the phonon dispersions of the intermolecular vibration in fcc solid C60 have been worked out. In recent years, these dispersions have attracted intensive interests from some investigators. The calculated results show an excellent agreement with the experimental data measuered by the inelastic neutron scattering method. This indicates that our result is a good description of the van der Waals interaction between molecules in solid C60 and is a good means to study properties of this solid.