\begin{table}%t
%\centering
\par
\caption{\label{Q-p-o} Partition functions for \emph{para-} and \emph{ortho-}H$_2$O$^+$, assuming LTE.}
\begin{tabular}[t]{r@{}lr@{}lr@{}l}
\hline \hline\noalign{\smallskip}
\multicolumn{2}{c}{$T$} & \multicolumn{2}{c}{$Q({\it para})$} & \multicolumn{2}{c}{$Q({\it ortho})$} \\
\hline
 300&.0   & 109&.1787 & 296.3567 \\
 225&.0   &  73&.4887 & 192.9372 \\
 150&.0   &  43&.0579 & 105.7512 \\
  75&.0   &  19&.0770 &  38.3647 \\
  37&.5   &  10&.4751 &  14.5910 \\
  18&.750 &   7&.3879 &   7.3124 \\
   9&.375 &   6&.2329 &   6.0584 \\
   5&.000 &   5&.9680 &   5.9982 \\
   2&.725 &   5&.9123 &   5.9961 \\
\hline
\end{tabular} 
\end{table}