Polyatomic Molecules and Molecular Crystals
Molecular crystals differ from the ionic and metallic variety in that the valence interaction forces between the atoms in the molecules are considerably greater than the intermolecular forces. By nature the inter-molecular forces in molecular crystals are those of Van der Waals attraction [4,5], linked with the mutual polarization of molecules. These forces also arise between neutral molecules and between molecules without inherent dipole moments. But even for molecules with dipole moments the Van der Waals interaction is dominant. At first glance this seems paradoxical, but it is explained by the strong dependence of multipolar static interactions on direction. In contrast to the Van der Waals interaction, the static effect diminishes on averaging over different orientations of the molecules.
KeywordsIrreducible Representation Molecular Crystal Polarization Spectrum Free Exciton Exciton Band
Unable to display preview. Download preview PDF.