\begin{table}%t6
\caption{\label{tab:acc}A comparison of fractionation from the accretion models. $T=10$~K, $n$(H$_2)=10^6$~cm$^{-3}$.}
%\centerline
{
\begin{tabular}{lllll}
\hline\hline
 & \multicolumn{2}{c}{\rneufneuf\ model} & \multicolumn{2}{c}{\rosu\ model} \\
Time (yr) & 10$^4$  & $6\times10^4$ & 10$^4$ & $6\times10^4$ \\ 
\hline
HD         & 2.94($-$5) & 2.13($-$5) & 3.05($-$5)   & 1.77($-$5)   \\
D$_2$      & 1.03($-$6) & 4.29($-$6) & 6.41($-$7)   & 5.54($-$6)   \\
H$_2$D$^+$ & 1.63     & 1.46   & 1.21    & 1.16   \\
HD$_2^+$   & 1.61     & 1.67   & 0.82    & 1.25   \\
D$_3^+$    & 6.46     & 21.7   & 1.00    & 4.96   \\
N$_2$D$^+$ & 2.90     & 8.58   & 0.92    & 2.78   \\
DCO$^+$    & 3.06     &  --    & 0.95    &  --    \\
DCS$^+$    & 1.81     &  --    & 0.65    &  --    \\
D          & 0.21     & 0.76   & 9.29($-$2)   & 0.18   \\
NH$_2$D    & 0.38     & 3.73   & 0.69    & 2.16   \\
NHD$_2$    & 0.14     & 3.70   & 0.17    & 1.46   \\
ND$_3$     & 2.38($-$3) & 0.68   & 6.79($-$3)   & 0.24   \\
ND         & 2.64     & 7.70   & 0.92     & 3.00   \\
HDCS       & 0.45     &  --    & 0.27    &  --    \\
D$_2$CS    & 1.80($-$2) &  --    & 1.65($-$2)   &  --    \\
HDCO       & 0.34     &  --    & 0.25    &  --    \\
D$_2$CO    & 2.63($-$2) &  --    & 1.37($-$2)   &  --    \\
OD         & 1.30     & (5.34) & 0.52    & (0.83)   \\
HDO        & 0.57     & (1.19) & 0.47    & (0.97)   \\
D$_2$O     & 4.86($-$2) & (0.73) & 8.75($-$2)   & (0.48)   \\
HDS   & 0.90   & --    & 0.90 & \\
D$_2$S & 0.03   & --    & 0.11 & \\
\hline
\end{tabular}}
\smallskip
Notes: $a(-b)$ implies $a\times10^{-b}$;~OD,~HDO and~D$_2$O fractional abundances at $6\times10^4$~yr are $<$10$^{-16}$. 
\end{table}