\begin{table}%t1
\caption{Statistical properties of the ortho and para forms of~D$_2$ (Herzberg \cite{herzberg}). The ortho nuclear spin states are associated with even values of the rotational quantum number, $J$, and the para states with odd $J$. Only the lowest rotational level of each modification was included in the model. For~D$_2^+$ and~D$_2$H$^+$, the statistical properties of the lowest ortho and para levels are the same as in the case of~D$_2$; but the lowest para level lies 42.0~K and 50.2~K, respectively, above the lowest ortho level, which is the ground level (Polyansky \& Tennyson \cite{polyansky99}; Ramanlal \& Tennyson \cite{ramanlal04}). }\label{D2}
%\centering
\par
\begin{tabular}{crcrccr}
\hline  \hline
Modification & $I_{\rm tot}$ & $\sum (2I_{\rm tot}+1)$ & $J$ & $(2J+1)$ & $(2J+1)\sum (2I_{\rm tot}+1)$ &  $E_J $ (K)    \\
\hline
ortho &	0, 2 & 6 & 0 & 1 & 6 & 0  \\
para  &	1    & 3 & 1 & 3 & 9 & 86.0 \\
\hline
\end{tabular}
\end{table}