--- trunk/tengDissertation/LiquidCrystal.tex 2006/06/27 01:33:33 2892 +++ trunk/tengDissertation/LiquidCrystal.tex 2006/06/27 03:06:49 2896 @@ -218,7 +218,8 @@ temperature and pressure. a $160\times 160 \times 120$ box. After the dipolar interactions are switched on, 2~ns NPTi cooling run with themostat of 2~ps and barostat of 50~ps were used to equilibrate the system to desired -temperature and pressure. +temperature and pressure. NPTi Production runs last for 40~ns with +time step of 20~fs. \subsection{Order Parameters} @@ -295,28 +296,7 @@ system. Fig.~\ref{LCFigure:gofrz}(b) implies the existence of the layered structure, and the peak at 27 \AA is attribute to the defect in the system. - -\begin{figure} -\centering -\includegraphics[width=4.5in]{snapshot.eps} -\caption[Snapshot of the molecular organization in the layered phase -formed at temperature T = 460K and pressure P = 1 atm]{Snapshot of -the molecular organization in the layered phase formed at -temperature T = 460K and pressure P = 1 atm. (a) diagonal view; (b) -side view.} \label{LCFigure:snapshot} -\end{figure} -\begin{figure} -\centering -\includegraphics[width=\linewidth]{gofr_gofz.eps} -\caption[Correlation Functions of a Bent-core Liquid Crystal System -at Temperature T = 460K and Pressure P = 10 atm]{Correlation -Functions of a Bent-core Liquid Crystal System at Temperature T = -460K and Pressure P = 10 atm. (a) radial correlation function -$g(r)$; and (b) density along the director $g(z)$.} -\label{LCFigure:gofrz} -\end{figure} - \subsection{Rotational Invariants} As a useful set of correlation functions to describe @@ -337,15 +317,54 @@ r_{ij} )((\hat x_i \cdot \hat x_j )^2 - (\hat x_i \ & & \left. - 2(\hat x_i \cdot \hat y_j )(\hat y_i \cdot \hat x_j ) - 2(\hat x_i \cdot \hat x_j )(\hat y_i \cdot \hat y_j )) \right>. \end{eqnarray} +The long range behavior of second rank orientational correlation +$S_{22}^{220} (r)$ in Fig~\ref{LCFigure:S22220} also confirm the +biaxiality of the system. -%\begin{equation} -%S_{00}^{221} (r) = - \frac{{\sqrt 3 }}{{\sqrt {10} }}\left\langle -%{\delta (r - r_{ij} )((\hat z_i \cdot \hat z_j )(\hat z_i \cdot -%\hat z_j \times \hat r_{ij} ))} \right\rangle -%\end{equation} +\begin{figure} +\centering +\includegraphics[width=4.5in]{snapshot.eps} +\caption[Snapshot of the molecular organization in the layered phase +formed at temperature T = 460K and pressure P = 1 atm]{Snapshot of +the molecular organization in the layered phase formed at +temperature T = 460K and pressure P = 1 atm. (a) diagonal view; (b) +side view.} \label{LCFigure:snapshot} +\end{figure} +\begin{figure} +\centering +\includegraphics[width=\linewidth]{gofr_gofz.eps} +\caption[Correlation Functions of a Bent-core Liquid Crystal System +at Temperature T = 460K and Pressure P = 10 atm]{Correlation +Functions of a Bent-core Liquid Crystal System at Temperature T = +460K and Pressure P = 10 atm. (a) radial correlation function +$g(r)$; and (b) density along the director $g(z)$.} +\label{LCFigure:gofrz} +\end{figure} + +\begin{figure} +\centering +\includegraphics[width=\linewidth]{s22_220.eps} +\caption[Average orientational correlation Correlation Functions of +a Bent-core Liquid Crystal System at Temperature T = 460K and +Pressure P = 10 atm]{Correlation Functions of a Bent-core Liquid +Crystal System at Temperature T = 460K and Pressure P = 10 atm. (a) +radial correlation function $g(r)$; and (b) density along the +director $g(z)$.} \label{LCFigure:S22220} +\end{figure} + \section{Conclusion} We have presented a simple dipolar three-site GB model for banana shaped molecules which are capable of forming smectic phases from -isotropic configuration. +isotropic configuration. Various order parameters and correlation +functions were used to characterized the structural properties of +these smectic phase. However, the forming layered structure still +had some defects because of the mismatching between the layer +structure spacing and the shape of simulation box. This mismatching +can be broken by using NPTf integrator in further simulations. The +role of terminal chain in controlling transition temperatures and +the type of mesophase formed have been studied +extensively\cite{Pelzl1999}. The the lack of flexibility in our +model due to the missing terminal chains could explained the fact +that we did not find evidence of chirality.