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open octagonal cavities that are typically greater than 6.3 \AA\ in |
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diameter. This relatively open overall structure leads to crystals |
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that are 0.07 g/cm$^3$ less dense on average than ice $I_h$. |
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+ |
\begin{figure} |
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\includegraphics[scale=1.0]{unitCell.eps} |
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\caption{Unit cells for (A) Ice-{\it i} and (B) Ice-2{\it i}, the elongated variant of Ice-{\it i}. For Ice-{\it i}, the $a$ to $c$ relation is given by $a = 1.0607c$, while for Ice-2{\it i}, $a = 0.8925c$.} |
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\label{iceiCell} |
120 |
+ |
\end{figure} |
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\begin{figure} |
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\includegraphics[scale=1.0]{orderedIcei.eps} |
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\caption{Image of a proton ordered crystal of Ice-{\it i} looking |
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+ |
down the (001) crystal face. The rows of water tetramers surrounded by |
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octagonal pores leads to a crystal structure that is significantly |
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+ |
less dense than ice $I_h$.} |
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\label{protOrder} |
128 |
+ |
\end{figure} |
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|
|
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Results in the previous study indicated that Ice-{\it i} is the |
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minimum energy crystal structure for the single point water models |