\begin{table}%t6
%\centering
\par
\caption{\label{tab:cdn4}Column densities in \pscm ~and molecular fraction $f$ for the dense PDR models. Numbers in parentheses refer to power of ten.}
\small \begin{tabular}{lllllllll}
\hline\hline
\noalign{\smallskip}
Model   & H &   \rm {H$_2$} & $f$ & D & HD  & C & CO  & CH \\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
RC   &   2.29(21)  & 8.21(21)  &0.88 & 3.29(16) &2.28(17) & 7.74(17) &  1.18(18) & 9.31(14)\\
MC  &       6.35(21)  & 6.18(21)& 0.66  & 3.25(16)& 2.46(17)& 5.1(17) & 1.10(18) & 1.02(15) \\
\hline
\end{tabular}
\end{table}