Transition Dipole Interaction and Intermolecular Potential of Carbon Disulfide and Sulfur Dioxide Crystals

The optical active normal frequencies and the heats of sublimation of carbon disulfide and sulfur dioxide crystals have been calculated. The interaction between the transition dipoles associated with the infrared active intermolecular modes has been taken into account by introducing coupling terms between the equivalent coordinates of neighboring molecules. The coupling force constants estimated from the infrared absorption intensities explain the observed trend of the factor group splittings of the ν3 mode of carbon disulfide and the ν1 and ν3 modes of sulfur dioxide. The splitting of the ν2 mode of carbon disulfide has been reproduced by taking account of the long range Coulomb interaction between the atomic charges.