\begin{table}%t5
%\centering
\par
\caption{\label{table1}Vibrational properties of the  ${\rm X~^3 \Sigma} ^-_g$ state of the C$_4$ molecule.}
\small \begin{tabular}{lcccc}
\hline
\hline\noalign{\smallskip}
& $\nu$ $\big(${\rm cm}$^{-1}\big)$ & IR int & $A_{1,0}$ (s$^{-1}$) & $\sum n_i A_{1,0}$~(s$^{-1}$)  \\
& & $\big($km.mole$^{-1}\big)$ & & \\
\hline
v1 & 172 & 27 & 0.01 & 0.34\\
v2 & 172 & 27 & 0.01 & 0.34\\
v3 & 352 & 0 & 0 & 0\\
v4 & 352 & 0  & 0 & 0\\
v5 & 908 & 0 & 0 & 0\\
v6 & 1548 & 312 & 89 & 342\\
v7 & 2032 & 0 & 0 & 0\\
\hline
\end{tabular}
\end{table}