\begin{table}%t6
\par
\caption{Vertical excitation energies (in eV) and dominant electron configuration of the lowest electronic 
states of $\textit{l}$-CSiCC. These energies are given with respect to the $X^3$ $\Sigma^{-}$ ground state.
\label{tab6}}
%\centerline
 {\begin{tabular}{c c c c}
\hline \hline
State & CASSCF/cc-pVT$Z^a$ & MRCI+Q/cc-pVT$Z^b$  & Electron configuration \\
\hline
$ X^3 \Sigma^- $ &
0.0 &
0.0 &
$ (11 \sigma)^2 (2 \pi)^4 (3 \pi)^2 $ 
\\
$ {}^1 \Delta $ &
0.43 &
0.69 &
$ (11 \sigma)^2 (2 \pi)^4 (3 \pi)^2 $
\\
$ {}^1 \Sigma^+ $ &
0.79 &
0.98 &
$ (11 \sigma)^2 (2 \pi)^4 (3 \pi)^2 $
\\
$ {}^3 \Pi $ &
1.17 &
1.11 &
$ (11 \sigma)^1 (2 \pi)^4 (3 \pi)^3 $
\\
$ {}^1 \Sigma^- $ &
1.62 &
2.19 &
$ (11 \sigma)^2 (2 \pi)^3 (3 \pi)^3 $
\\
$ {}^1 \Pi $ &
2.73 &
2.27 &
$ (11 \sigma)^1 (2 \pi)^4 (3 \pi)^3 $
\\
$ {}^3 \Delta $ &
1.97 &
2.32 &
$ (11 \sigma)^2 (2 \pi)^3 (3 \pi)^3 $
\\
$ {}^3 \Sigma^+ $ &
1.71 &
2.38 &
$ (11 \sigma)^2 (2 \pi)^3 (3 \pi)^3 $
\\
$ {}^5 \Pi $ &
3.20 &
3.31 &
$ (11 \sigma)^1 (2 \pi)^4 (3 \pi)^2 (4 \pi)^1 $
\\
$ {}^1 \Pi $ &
3.87 &
3.48 &
$ (11 \sigma)^1 (2 \pi)^4 (3 \pi)^3 $
\\
$ {}^3 \Pi $ &
3.44 &
3.55 &
$ (11 \sigma)^1 (2 \pi)^3 (3 \pi)^4 $
\\
$ {}^5 \Sigma^- $ &
3.02 &
3.69 &
$ (11 \sigma)^2 (2 \pi)^3 (3 \pi)^2 (4 \pi)^1 $
\\
$ {}^5 \Sigma^+ $ &
3.98 &
4.37 &
$ (11 \sigma)^2 (2 \pi)^4 (3 \pi)^2 (4 \pi)^1 $
\\
$ {}^5 \Pi $ &
4.08 &
4.67 &
$ (11 \sigma)^2 (12 \sigma)^1 (2 \pi)^3 (3 \pi)^2 $
\\ 
\hline
\end{tabular}}
\par
\smallskip
$^a$ $E$(CASSCF/cc-pVTZ) = --402.347488 $E_{\rm h}$; 
$^b$ $E$(MRCI+Q/cc-pVTZ) = --402.781500 $E_{\rm h}$.
\end{table}