On the determination of intermolecular potentials

The definition and computational aspects of the intermolecular potential energy function (hereafter simply called the intermolecular potential or the potential) are discussed. A very convenient method of determining tlie intermolecular potential by direct quantum mechanical calculation is developed and illustrated by application to the interaction of two ground state heIium atoms. A summary is also presented of the relationship between the intermolecular potential and the bulk properties of a gas to facilitate the investigation of the semi-empirical method of determining the potentiaI. This approach is applied to the pair interactions of CH4,CF4 and SF6 molecules. Both the semi-empiricaI and quantum mechanicaI methods are then applied to the question of the non-additivity of the intermolecular potential.