\begin{table}%t4
\caption{\label{tab:standard}The initial abundances, relative to total~H, used in the models.}
%\centering
\par
\begin{tabular}{lclc}
\hline\hline
Species & Abundance & Species & Abundance\\
\hline
H$_2$ & $5\times10^{-1}$ & Si & $2\times10^{-8}$\\
He & $1\times10^{-1}$ & Fe$^+$ & $1\times10^{-8}$\\
C$^+$ & $7.3\times10^{-5}$ & S$^+$ & $1\times10^{-7}$ \\
N & $2.14\times10^{-5}$ &~HD & $1.6\times10^{-5}$ \\
O & $1.76\times10^{-4}$ & \\
\hline
\end{tabular}
\end{table}