Orientational order in simple dipolar liquid-crystal models

The orientational order in simple systems of dipolar hard-core molecules is determined by Monte Carlo simulations. Dipolar hard spherocylinders are shown to form a monolayer smectic-A phase with unpolarized layers. In the columnar phase of dipolar cut spheres, evidence is given for a transition, with increasing dipole moment, from a phase with unpolarized columns to a phase with completely polarized columns arranged with antiferroelectric order. Ferroelectric orientational order is demonstrated for strong dipolar hard spheres.