(229e) Thermodynamic Properties of Polar Fluids

The thermodynamic properties of fluids are ultimately determined by the nature and type of intermolecular interactions. Simple fluids such as, the inert gases can often be adequately described by intermolecular potentials that incorporate the contributions for dispersion forces and repulsive interactions. In contrast, fluids of practical interest commonly involve polar forces arising from interactions between permanent dipoles and/or quadrupoles. Indeed, there are many examples of fluids that have both dipolar and quadrupole interactions. It is difficult to isolate the affect of such competing non-polar interactions on experimentally observed properties. It is in this context that molecular simulation has a useful role. In this work, we report molecular dynamics simulation of the effect of dipole and quadrupole interactions on the thermodynamics and phase behaviour of both pure fluids and fluid mixtures. In particular, mixtures of different types of polarity are studied allowing us to observe the influence of dissimilar polar interactions.