Solid state effects in the molecular crystals of Cl 2, Br 2 and I 2

Abstract

The solid halogens CL 2, Br 2 and I 2 are a model system for studying the intermolecular interactions in a molecular crystal. Self-consistent energy band-structure calculations based on the local density approximation (LDA) are performed by the full potential linearised augmented plane wave method. A geometry optimisation in terms of bond length and rigid rotation of the molecules is done by total energy minimisation and yields results close to experiment. The electronic charge density is obtained from which the electric field gradient (EFG) is determined on a first principles basis. The EFG asymmetry parameter η turns out to be very sensitive to the intermolecular interactions, which are well described by the present method.