  Ionic liquid crystals (ILCs) are anisotropic mesogenic molecules which carry
charges and therefore combine properties of liquid crystals, e.g., the
formation of mesophases, and of ionic liquids, such as low melting temperatures
and tiny triple-point pressures. Previous density functional calculations have
revealed that the phase behavior of ILCs is strongly affected by their
molecular properties, i.e., their aspect ratio, the loci of the charges, and
their interaction strengths. Here, we report new findings concerning the phase
behavior of ILCs as obtained by density functional theory and Monte Carlo
simulations. The most important result is the occurrence of a novel, wide
smectic-A phase $S_{AW}$, at low temperature, the layer spacing of which is
larger than that of the ordinary high-temperature smectic-A phase $S_{A}$.
Unlike the ordinary smectic $S_A$ phase, the structure of the $S_{AW}$ phase
consists of alternating layers of particles oriented parallel to the layer
normal and oriented perpendicular to it.
