The phonon dispersion relations for the lowest-ten external branches, and for wave vectors along the optic axis, ahve been measured in calcite, CaC${\mathrm{O}}_3$, at room temperature, by means of inelastic-neutron-scattering techniques. The results are shown to be consistent with a simple shell model containing ten adjustable parameters.

• Received 9 March 1973

DOI:https://doi.org/10.1103/PhysRevB.8.4795