--- trunk/tengDissertation/LiquidCrystal.tex 2006/06/01 20:14:11 2784 +++ trunk/tengDissertation/LiquidCrystal.tex 2006/06/02 21:31:49 2785 @@ -116,8 +116,13 @@ orientation and position dependent range ($\sigma$) an potential used to mimic the apolar characteristics of liquid crystal molecules takes the familiar form of Lennard-Jones function with orientation and position dependent range ($\sigma$) and well depth -($\epsilon$) parameters. It can can be expressed as, +($\epsilon$) parameters. The potential between a pair of three-site +banana-shaped molecules $a$ and $b$ is given by \begin{equation} +V_{ab}^{GB} = \sum\limits_{i \in a,j \in b} {V_{ij}^{GB} }. +\end{equation} +Every site-site interaction can can be expressed as, +\begin{equation} V_{ij}^{GB} = 4\epsilon (\hat u_i ,\hat u_j ,\hat r_{ij} )\left[ {\left( {\frac{{\sigma _0 }}{{r_{ij} - \sigma (\hat u_i ,\hat u_j ,\hat r_{ij} )}}} \right)^{12} - \left( {\frac{{\sigma _0 @@ -146,7 +151,7 @@ and the end-to-end length of the ellipsoid, respective \label{LCEquation:chi} \end{equation} Here, $\sigma_ s$ and $\sigma_{e}$ refer to the side-by-side breadth -and the end-to-end length of the ellipsoid, respectively. Twell +and the end-to-end length of the ellipsoid, respectively. The well depth parameters takes the form \begin{equation} \epsilon (\hat u_i ,\hat u_j ,\hat r_{ij} ) = \epsilon _0 \epsilon @@ -169,7 +174,7 @@ ratio between \textit{end-to-end} well depth $\epsilon where the well depth anisotropy parameter $\chi '$ depends on the ratio between \textit{end-to-end} well depth $\epsilon _e$ and \textit{side-by-side} well depth $\epsilon_s$, -\begin{eqaution} +\begin{equation} \chi ' = \frac{{1 - (\epsilon _e /\epsilon _s )^{1/\mu} }}{{1 + (\epsilon _e /\epsilon _s )^{1/\mu} }}. \end{equation} @@ -182,7 +187,7 @@ ratio between \textit{end-to-end} well depth $\epsilon \begin{figure} \centering -\includegraphics[width=\linewidth]{bananGB_grained.eps} +\includegraphics[width=\linewidth]{bananGB.eps} \caption[]{} \label{LCFigure:BananaGB} \end{figure} @@ -194,6 +199,16 @@ vectors for a pair of Gay-Berne molecules} \label{LCFigure:GBScheme} \end{figure} +To account for the permanent dipolar interactions, there should be +an electrostatic interaction term of the form +\begin{equation} +V_{ab}^{dp} = \sum\limits_{i \in a,j \in b} {\frac{1}{{4\pi +\epsilon _{fs} }}\left[ {\frac{{\mu _i \cdot \mu _j }}{{r_{ij}^3 }} +- \frac{{3\left( {\mu _i \cdot r_{ij} } \right)\left( {\mu _i \cdot +r_{ij} } \right)}}{{r_{ij}^5 }}} \right]} +\end{equation} +where $\epsilon _{fs}$ is the permittivity of free space. + \section{\label{liquidCrystalSection:methods}Methods} \section{\label{liquidCrystalSection:resultDiscussion}Results and Discussion}