\begin{table}%[htb]%t9
\par
%\centering
\par
\caption{Vibrational frequencies for the two calculated CO$_2$
dimers (B3LYP/6-311++G*).
Calculated intensities (km~mol$^{-1}$) are in\protect  parentheses.\label{co2_ir}}
\par
\begin{tabular}{c c c}
\hline\hline
 	& "Slipped" & "Constrained linear"	\\
 	& (cm$^{-1}$)  	& (cm$^{-1}$) \\
\hline 
 	& 10.63 (0.0) & --10.78 (0.0)	\\
 	& 21.95 (0.0) & 13.79 (0.0) 	\\
 	& 39.09 (0.1) & 38.77 (0.1)	\\
 	& 68.10 (0.0) & 52.65 (0.0)	\\
 	& 665.57 (48.4) & 665.89 (47.6)	\\
 	& 667.45 (1.2) & 666.17 (31.3)	\\
 	& 667.88 (28.0) & 667.70 (7.0)	\\
 	& 670.01 (64.0) & 669.88 (58.5)	\\
 	& 1373.12 (0.0) & 1373.02 (0.0)	\\
 	& 1373.68 (0.1) & 1374.62 (0.0)	\\
 	& 2420.40 (1199.5) & 2420.21 (689.0)	\\
 	& 2421.47 (241.4) & 2422.39 (765.2)	\\
 Energies	& 0.55 & 0.51	\\
(kcal~mol$^{-1}$) \\
\hline
\end{tabular}
\end{table}