--- trunk/tengDissertation/LiquidCrystal.tex 2006/05/31 04:29:44 2781 +++ trunk/tengDissertation/LiquidCrystal.tex 2006/06/01 05:11:14 2782 @@ -32,14 +32,47 @@ second-order nonlinear optical devices. supramolecular chirality, the spontaneous polarization arises in ferroelectric (FE) and antiferroelectic (AF) switching of smectic liquid crystal phases, demonstrating some promising applications in -second-order nonlinear optical devices. +second-order nonlinear optical devices. The most widely investigated +mesophase formed by banana-shaped moleculed is the $\text{B}_2$ +phase, which is also referred to as $\text{SmCP}$. Of the most +important discover in this tilt lamellar phase is the four distinct +packing arrangements (two conglomerates and two macroscopic +racemates), which depend on the tilt direction and the polar +direction of the molecule in adjacent layer (see +Fig.~\cite{LCFig:SMCP}). -The most widely investigated mesophase formed by banana-shaped -moleculed is the $\text{B}_2$ phase, which is also known as -$\text{SmCP}$. +%general banana-shaped molecule modeling +Many liquid crystal synthesis experiments suggest that the +occurrence of polarity and chirality strongly relies on the +molecular structure and intermolecular interaction. From a +theoretical point of view, it is of fundamental interest to study +the structural properties of liquid crystal phases formed by +banana-shaped molecules and understand their connection to the +molecular structure, especially with respect to the spontaneous +achiral symmetry breaking. As a complementary tool to experiment, +computer simulation can provide unique insight into molecular +ordering and phase behavior, and hence improve the development of +new experiments and theories. In the last two decades, all-atom +models have been adopted to investigate the structural properties of +smectic arrangements\cite{Cook2000, Lansac2001}, as well as other +bulk properties, such as rotational viscosity and flexoelectric +coefficients\cite{Cheung2002, Cheung2004}. However, due to the +limitation of time scale required for phase +transition\cite{Wilson1999} and the length scale required for +representing bulk behavior, the dominant models in the field of +liquid crystal phase behavior are generic +models\cite{Lebwohl1972,Perram1984, Gay1981}, which are based on the +observation that liquid crystal order is exhibited by a range of +non-molecular bodies with high shape anisotropies. Previous +simulation studies using hard spherocylinder dimer +model\cite{Camp1999} produce nematic phases, while hard rod +simulation studies identified a Landau point\cite{Bates2005}, at +which the isotropic phase undergoes a transition directly to the +biaxial nematic, as well as some possible liquid crystal +phases\cite{Lansac2003}. Other anisotropic models using Gay-Berne +potential give the evidence of the novel packing arrangement of +bent-core molecules\cite{Memmer2002,Orlandi2006}. -%Previous Theoretical Studies - \section{\label{liquidCrystalSection:model}Model} \section{\label{liquidCrystalSection:methods}Methods}