\begin{table}%t9
%\centering
\par
\caption{Some relevant energy levels and ionization potentials (in eV) from our MCDF calculations and from \citet{nist} for C-like ions. The energy of each term is obtained as the mean of the energy levels weighted statistically.\label{tab9}}
\begin{tabular}{lllll}
\hline\hline
& \multicolumn{2}{c}{N$^{3+}$} & \multicolumn{2}{c}{O$^{4+}$} \\
Level & MCDF & NIST & MCDF & NIST \\
\hline
2s$^{2}$2p$^{2}$ $^{3}$P & 0 & 0 & 0 & 0 \\
2s$^{2}$2p$^{2}$ $^{1}$D & 3.36 & 3.13 & 4.16 & 3.76  \\
2s$^{2}$2p$^{2}$ $^{1}$S & 6.85 & 6.64 & 8.18 & 7.92  \\
2s2p$^{3}$ $^{5}$S & 8.33 & 9.20 & 10.15 & 10.96  \\
$E_{\rm IP}$ (2s$^{2}$2p $^{2}$P) & 86.38 & 87.14 & 125.44 & 126.22 \\
$E_{\rm IP}$ (2s2p$^{2}$ $^4$P) & 96.50 & 97.82 & 137.15 & 138.72 \\
$E_{\rm IP}$ (2s2p$^2$ $^2$D) & 105.89 & 106.09 & 148.25 & 148.41 \\
$E_{\rm IP}$ (2s2p$^2$ $^2$S) & 111.08 & 111.64 & 154.54 & 154.84 \\
$E_{\rm IP}$ (2s2p$^2$ $^2$P) & 114.29 & 113.82 & 157.87 & 157.22 \\
	\hline
	\end{tabular}
\end{table}