COMPUTER-SIMULATIONS OF QUASI-LATTICE MODELS FOR NOVEL FERROELECTRIC LIQUID-CRYSTALS

It has been suggested that ferroelectric smectic phases may be formed by "fraternal-twin" liquid-crystal molecules, consisting of two very different mesogens bonded together by an appropriate spacer [R. G. Petschek and K. M. Wiefling, Phys. Rev. Lett. 59, 343 (1987)]. We discuss the range in which these ferroelectric phases appear in a Monte Carlo simulation of a simple computer model for such mesogens. The mesogens consist of two identical flexible segments that are bonded to two rigid segments with very different lengths which, in turn, are bonded together by a flexible segment. In the computer model these monomers can move freely in one direction, but are constrained to lie on a hexagonal, lattice of rods in the other two directions, roughly the packing expected in a smectic-B crystal. The flexible segments are modeled by springs, and there is an energy cost for the overlap of flexible and rigid segments on neighboring lattice rods. The region in which polar (flexible, short rigid, flexible, long rigid, flexible) smectic layers form will be discussed.