| 199 |
|
$\frac{V}{\text{\AA}}$. The three field environments were, 1) no field |
| 200 |
|
applied, 2) 0.01 $\frac{V}{\text{\AA}}$ (0.5 V) and 3) 0.024 |
| 201 |
|
$\frac{V}{\text{\AA}}$ (1.2 V). Each field was applied in the |
| 202 |
< |
Z-axis of the simulation box. |
| 202 |
> |
Z-axis of the simulation box. For the simplicity of this paper, |
| 203 |
> |
each field will be called zero, partial and full, respectively. |
| 204 |
|
|
| 205 |
|
For quantum calculation of the nitrile bond frequency, Gaussian 09 was |
| 206 |
|
used. A single 5CB molecule was selected for the center of the |
| 257 |
|
$S$ is the largest eigenvalue of $Q_{\alpha \beta}$, and the |
| 258 |
|
corresponding eigenvector defines the director axis for the phase. |
| 259 |
|
$S$ takes on values close to 1 in highly ordered phases, but falls to |
| 260 |
< |
zero for isotropic fluids. |
| 260 |
> |
zero for isotropic fluids. In the context of 5CB, this value would be |
| 261 |
> |
close to zero for its isotropic phase and raise closer to one as it |
| 262 |
> |
moved to the nematic and crystalline phases. |
| 263 |
> |
|
| 264 |
> |
This value indicates phases changes at temperature boundaries but also |
| 265 |
> |
when a phase changes occurs due to external field applications. In |
| 266 |
> |
Figure 1, this phase change can be clearly seen over the course of 60 |
| 267 |
> |
ns. Each system starts with an ordering paramter near 0.1 to 0.2, |
| 268 |
> |
which is an isotropic phase. Over the course 10 ns, the full external field |
| 269 |
> |
causes a shift in the ordering of the system to 0.5, the nematic phase |
| 270 |
> |
of the liquid crystal. This change is consistent over the full 50 ns |
| 271 |
> |
with no drop back into the isotropic phase. This change is clearly |
| 272 |
> |
field induced and stable over a long period of simulation time. |
| 273 |
> |
|
| 274 |
> |
Interestingly, the field that is needed to switch the phase of 5CB |
| 275 |
> |
macroscopically is larger than 1 V. However, in this case, only a |
| 276 |
> |
voltage of 1.2 V was need to induce a phase change. This is impart due |
| 277 |
> |
to the distance the field is being applied across. At such a small |
| 278 |
> |
distance, the field is much larger than the macroscopic and thus |
| 279 |
> |
easily induces a field dependent phase change. |
| 280 |
|
|
| 281 |
+ |
This change in phase was followed by two courses of further |
| 282 |
+ |
simulation. First, was replacement of the static nitrile bond with a |
| 283 |
+ |
morse oscillator bond. This was then simulated for a period of time |
| 284 |
+ |
and a classical spetrum was calculated. Second, ab intio calcualtions were performe to investigate |
| 285 |
+ |
if the phase change caused any change spectrum from quantum |
| 286 |
+ |
effects. |
| 287 |
+ |
|
| 288 |
+ |
In respect to the classical calculations, it was first seen if previous |
| 289 |
+ |
studies of nitriles within water and neat simulation done by Cho |
| 290 |
+ |
et. al. could be used for the spectrum. |
| 291 |
+ |
|
| 292 |
+ |
After Gaussian calculations were performed on a set of snapshots, any |
| 293 |
+ |
|
| 294 |
|
\begin{figure} |
| 295 |
|
\includegraphics[trim = 5mm 10mm 3mm 10mm, clip, width=3.25in]{P2} |
| 296 |
< |
\caption{Order Parameter} |
| 296 |
> |
\caption{Ordering of each external field application over the course |
| 297 |
> |
of 60 ns with a sampling every 100 ps. Each trajectory was started |
| 298 |
> |
after equilibration with zero field applied.} |
| 299 |
|
\label{fig:orderParameter} |
| 300 |
|
\end{figure} |
| 301 |
|
|
| 302 |
|
\begin{figure} |
| 303 |
|
\includegraphics[width=3.25in]{2Spectra} |
| 304 |
< |
\caption{The classically calculated nitrile bond spetrum from } |
| 304 |
> |
\caption{The classically calculated nitrile bond spetrum for no |
| 305 |
> |
external field application (black) and full external field |
| 306 |
> |
application (red)} |
| 307 |
|
\label{fig:twoSpectra} |
| 308 |
|
\end{figure} |
| 309 |
|
|
| 273 |
– |
|
| 310 |
|
\begin{figure} |
| 311 |
|
\centering |
| 312 |
|
\begin{subfigure}[b]{0.3\textwidth} |
