Construction and Use of Central Force Models for the Theory of Polyatomic Fluids

In order to avoid technical problems posed by nonspherical interactions in the statistical mechanics of liquids, central force models can be devised to describe polyatomic substances. In this approach separate spherical potentials exist for each type of atomic pair. In the case of water, three functions are necessary: V OO (r), V HH (r), and V OH (r); they can be selected so that proper molecules spontaneously form and engage in linear hydrogen bonds. In addition to conventional properties, central force models permit study of molecular vibration and dissociation. Details for NH 3 , H 2 O, HF, and CH 4 are presented.