ORIENTATIONAL ORDER IN SIMPLE DIPOLAR FLUIDS - DENSITY-FUNCTIONAL THEORY AND ABSOLUTE-STABILITY CONDITIONS

The formation of ferroelectric liquid crystals by simple dipolar model s is investigated using density-functional theory and absolute-stabili ty analysis. It is emphasized that for such systems well defined resul ts can only be found by specifying exactly how the long-range dipolar interactions are treated. Explicit formal expressions are derived for mean-reaction-field boundary conditions and these are combined with in tegral-equation approximations in order to obtain numerical results fo r fluids of dipolar hard and soft spheres. The calculations predict is otropic-to-ferroelectric-nematic transitions in qualitative agreement with computer simulations. The quantitative agreement, however, is rat her poor.