\begin{table}%tb2
%\begin{center}
\par
\caption{Summary of the results from the general parameter study*.}
\label{tchem}
\begin{tabular}{lccc} \hline\hline
Molecule & X-rays ($F_{\rm X}$) & FUV ($G_0$) & FUV ($G_0$) \\ 
         & erg~s$^{-1}$~cm$^{-2}$ & $T\lesssim 300$~K & $T\gtrsim 300$~K \\ \hline 
CN (const.) & $\gtrsim$$10^{-4}$ & $\gtrsim$5 & $\gtrsim$5 \\
CN (jump)   & $\gtrsim$$10^{-3}$ & $\gtrsim$5 & $\gtrsim$5 \\
NO (const.) & $0$--$10^{-2}$ & -- & $\gtrsim$5 \\
NO (jump)   & $\gtrsim$$10^{-3}$ & -- & $\gtrsim$5 \\
SO$^+$ (const.) & $\gtrsim$$10^{-3}$ & -- & $\gtrsim$5 \\
SO$^+$ (jump) & $\gtrsim$$10^{-2}$ & -- & $\gtrsim$5 \\
CO$^+$ (const.) & $\gtrsim$$10^{-1}$ & -- & $\gtrsim$5 \\ 
CO$^+$ (jump) & $>$1 & -- & $\gtrsim$5 \\ \hline
\end{tabular}
\parbox{9cm}{
* The lower limit or range of X-ray and FUV fluxes for each molecule corresponds to 
the values that either fit the observed constant fractional abundances or the 
jump abundances $(x_{\rm 100K}, x_{\rm XDR})$. NO, SO$^+$ and CO$^+$ cannot be modeled with 
$G_0 \gtrsim 5$ and $T \lesssim 300$~K.} 
%\end{center}
\par
\end{table}