We present results of an ab initio calculation of the static and dynamical properties of the chlorine molecular crystal. The equilibrium ground-state properties are evaluated employing density-functional theory within the local-density approximation and the plane-wave pseudopotential method. Phonon frequencies and eigenvectors at the Γ and Y point of the Brillouin zone are calculated using density-functional perturbation theory within the linear-response approach. are accordingly too low. As a result, the intermolecular distances are in good agreement with experiment and so are most of the calculated external phonon frequencies. On the other hand, the intramolecular distance turns out too large and the internal phonon frequencies are accordingly too low.

• Received 5 August 1994

DOI:https://doi.org/10.1103/PhysRevB.51.210