\begin{table}%t1
%\centering
\par
\caption{Configurations used in the SSTRUCT model.}\label{tbl.configs}
\begin{tabular}{llll}
\hline
\hline
Even  && Odd &\\
\hline
3s$^2$3p$^2$&3s$^2$3d$^2$&3s3p$^3$&3s$^2$3p3d \\
3s$^2$3p4p&3s$^2$3p4f&3s$^2$3p4s&3s$^2$3p4d\\
3s3p$^2$3d&3s3p$^2$4s&3s3p$^2$4p&3s3p$^2$4f \\
3s3p$^2$4d&3s$^2$3d4s&3s3p3d$^2$&3s$^2$3d4p \\
3s$^2$3d4d&3p$^3$4s&3s$^2$3d4f&3p$^3$3d\\
3p$^3$4d&3p$^4$&3p$^3$4p \\
3p$^2$3d$^2$&\\
\hline
\end{tabular}
\end{table}