Lattice Dynamics of Graphite

The lattice dynamics of graphite have been studied using a tensor force model. Force constant values for interactions between atoms in‐plane have been transferred from the naphthalene molecule. It is shown that the agreement between theory and neutron scattering data is very good, indicating that the molecular constants form a very good approximation to the crystal force constants. Significant differences are, however, found between the present calculations and those of Nicklow et al. using an axially symmetric model, regarding some out‐of‐plane modes. It is assumed that these arise from the restrictions of the axially symmetric model. It is also shown that restoring forces corresponding to twisting motions about CC bonds in the plane are very small.