  We explore the phase behavior and structure of orthogonal smectic liquid
crystals consisting of bent-core molecules (BCMs) by means of Monte Carlo
molecular simulations. A simple athermal molecular model is introduced that
describes the basic features of the BCMs. Phase transitions between uniaxial
and biaxial (antiferroelectric) orthogonal smectics are obtained. The results
indicate the presence of local in-plane polar correlations in the uniaxial
smectic phase. The macroscopic uniaxial-biaxial transformation is rationalized
in terms of local polar correlations giving rise to polar domains. The size of
these polar domains grows larger under the action of an external vector field
and their internal ordering is enhanced, leading to field-induced biaxial
order-disorder transitions.
