| 319 |
|
\includegraphics[width=\linewidth]{./figures/ssdDense.pdf} |
| 320 |
|
\caption{ Density versus temperature for TIP3P, SPC/E, TIP4P, SSD, |
| 321 |
|
SSD with a reaction field, and |
| 322 |
< |
experiment.\cite{Jorgensen98b,Clancy94,CRC80}. Note that using a |
| 322 |
> |
experiment.\cite{Jorgensen98b,Baez94,CRC80}. Note that using a |
| 323 |
|
reaction field lowers the density more than the already lowered SSD |
| 324 |
|
densities. The lower than expected densities for the SSD model |
| 325 |
|
prompted the original reparametrization of SSD to SSD1.\cite{Tan03}} |
| 329 |
|
The density maximum for SSD compares quite favorably to other simple |
| 330 |
|
water models. Figure \ref{fig:ssdDense} also shows calculated |
| 331 |
|
densities of several other models and experiment obtained from other |
| 332 |
< |
sources.\cite{Jorgensen98b,Clancy94,CRC80} Of the listed simple water |
| 332 |
> |
sources.\cite{Jorgensen98b,Baez94,CRC80} Of the listed simple water |
| 333 |
|
models, SSD has a temperature closest to the experimentally observed |
| 334 |
|
density maximum. Of the {\it charge-based} models in figure |
| 335 |
|
\ref{fig:ssdDense}, TIP4P has a density maximum behavior most like |
| 367 |
|
density maximum location, down to 245K, is observed. This is a more |
| 368 |
|
accurate comparison to the other listed water models, in that no long |
| 369 |
|
range corrections were applied in those |
| 370 |
< |
simulations.\cite{Clancy94,Jorgensen98b} However, even without the |
| 370 |
> |
simulations.\cite{Baez94,Jorgensen98b} However, even without the |
| 371 |
|
reaction field, the density around 300K is still significantly lower |
| 372 |
|
than experiment and comparable water models. This anomalous behavior |
| 373 |
|
was what lead Tan {\it et al.} to recently reparametrize |
| 389 |
|
mean-square displacement as a function of time.\cite{Allen87} The |
| 390 |
|
averaged results from five sets of {\it NVE} simulations are displayed |
| 391 |
|
in figure \ref{fig:ssdDiffuse}, alongside experimental, SPC/E, and TIP5P |
| 392 |
< |
results.\cite{Gillen72,Holz00,Clancy94,Mahoney01} |
| 392 |
> |
results.\cite{Gillen72,Holz00,Baez94,Mahoney01} |
| 393 |
|
|
| 394 |
|
\begin{figure} |
| 395 |
|
\centering |
| 396 |
|
\includegraphics[width=\linewidth]{./figures/ssdDiffuse.pdf} |
| 397 |
|
\caption{ Average self-diffusion constant as a function of temperature for |
| 398 |
|
SSD, SPC/E, and TIP5P compared with experimental |
| 399 |
< |
data.\cite{Clancy94,Mahoney01,Gillen72,Holz00} Of the three water |
| 399 |
> |
data.\cite{Baez94,Mahoney01,Gillen72,Holz00} Of the three water |
| 400 |
|
models shown, SSD has the least deviation from the experimental |
| 401 |
|
values. The rapidly increasing diffusion constants for TIP5P and SSD |
| 402 |
|
correspond to significant decreases in density at the higher |
| 674 |
|
\includegraphics[width=\linewidth]{./figures/ssdeDense.pdf} |
| 675 |
|
\caption{ Comparison of densities calculated with SSD/E to |
| 676 |
|
SSD1 without a reaction field, TIP3P, SPC/E, TIP5P, and |
| 677 |
< |
experiment.\cite{Jorgensen98b,Clancy94,Mahoney00,CRC80} Both SSD1 and |
| 677 |
> |
experiment.\cite{Jorgensen98b,Baez94,Mahoney00,CRC80} Both SSD1 and |
| 678 |
|
SSD/E show good agreement with experiment when the long-range |
| 679 |
|
correction is neglected.} |
| 680 |
|
\label{fig:ssdeDense} |
| 705 |
|
\includegraphics[width=\linewidth]{./figures/ssdrfDense.pdf} |
| 706 |
|
\caption{ Comparison of densities calculated with SSD/RF to |
| 707 |
|
SSD1 with a reaction field, TIP3P, SPC/E, TIP5P, and |
| 708 |
< |
experiment.\cite{Jorgensen98b,Clancy94,Mahoney00,CRC80} This plot |
| 708 |
> |
experiment.\cite{Jorgensen98b,Baez94,Mahoney00,CRC80} This plot |
| 709 |
|
shows the benefit afforded by the reparametrization for use with a |
| 710 |
|
reaction field correction - SSD/RF provides significantly more |
| 711 |
|
accurate densities than SSD1 when performing room temperature |
