\begin{table}%t2
\par
\caption{\label{table2}Reactions and rate coefficients adopted in the chemical
model.}
%\centerline
 {\tiny\begin{tabular}{lll}
\hline\hline
Cosmic rays ionization & Rate in s$^{-1}$, with $\zeta$ the rate of cosmic
ray ionization of \hm .&Ref. \\
\hline
H + CR $\rightarrow$ H+ + e&0.46$\zeta$&c\\
D + CR $\rightarrow$ H+ + e&0.46$\zeta$&c\\
H2 + CR $\rightarrow$ H + H&1.5$\zeta$&c\\
H2 + CR $\rightarrow$ H2+ + e &0.96$\zeta$&c\\
HD + CR $\rightarrow$ H + D&1.5$\zeta$&c\\
HD + CR $\rightarrow$ HD+ + e &0.96$\zeta$&c\\
D2 + CR $\rightarrow$ D + D&1.5$\zeta$&c\\
\hline
Reaction & Rate in cm$^3$ s$^{-1}$& Ref. \\
\hline
H2 + D $\rightarrow$ H + HD& dex$(-56.4737+5.88886\times
\log({\rm Tg})+7.196292\times \log({\rm Tg})^2+2.25069\times \log({\rm Tg})^3-2.16903\times
\log({\rm Tg})^4$&a\\
&$+0.317887\times \log({\rm Tg})^5$&\\
HD + H $\rightarrow$ H2 + D&$5.25\times  10^{-11}\times \exp(-4430/{\rm Tg})$\ if
Tg $<$ 200~K&\\
&$5.25\times  10^{-11}\times \exp((-4430/{\rm Tg})+(173~900/{\rm Tg}^2))$ if Tg $>$
200~K&a\\
D+ + H2 $\rightarrow$  H+ + HD&$10^{-9}\times (0.417+0.846\times
\log({\rm Tg})-0.137\times \log({\rm Tg})^2$&a\\
H+ + HD $\rightarrow$ D+ + H2 &$1.1\times  10^{-9} \times  \exp{-488/{\rm Tg}}$&a\\
H+ + D$\rightarrow$ D+ + H&$2\times 10^{-10}\times {\rm Tg}^{0.402}\times
\exp{-37.1/{\rm Tg}}-3.31\times 10^{-17}\times {\rm Tg}^{1.48}$&a\\
H + D+ $\rightarrow$ H+ + D&$2.06\times  10^{-10}\times {\rm Tg}^{0.396} \times
\exp{-33/{\rm Tg}}+2.03\times  10^{-9}\times  {\rm Tg}^{-0.332}$&a\\
HD + D+ $\rightarrow$ D2 + H+&$1\times 10^{-9}$&a\\
H+ + D2 $\rightarrow$ D+ + HD&$2.1\times  10^{-9}\times \exp{-491/{\rm Tg}}$&a\\
H2 + H+ $\rightarrow$ H2+ + H&$\exp(-21237.15/{\rm Tg})\times (3.3232183\times
10^{-7}+3.3735382\times 10^{-7}\times \ln({\rm Tg})-1.4491368\times 10^{-7}\times
\ln({\rm Tg})^2$&\\
&$+3.4172805\times 10^{-8}\times \ln({\rm Tg})^3-4.7813720\times 10^{-9}\times
\ln({\rm Tg})^4+3.9731542\times 10^{-10}\times \ln({\rm Tg})^5$&\\
&$-1.8171411\times 10^{-11}\times \ln({\rm Tg})^6+3.5311932\times 10^{-13}\times
\ln({\rm Tg})^7$&b\\
H + H+ $\rightarrow$ H2+ + phot&dex$(-19.38-1.523\times
\log({\rm Tg})+1.118\times (\log({\rm Tg}))^2-0.1269\times (\log({\rm Tg})^3))$&a\\
H + H2+ $\rightarrow$ H2 + H+ &6.4~$\times $~10$^{-10}$&a\\
H + HD+ $\rightarrow$ H2 + D+ &1~$\times $~10$^{-9}$&a\\
H+ + e $\rightarrow$ H + phot& 2.753~$\times 10^{-14}
\times (315614/{\rm Tg})^{1.5}\times (1+(115188/{\rm Tg})^{0.407})^{-2.242}$&b, caseB\\
D+ + e $\rightarrow$ D+ phot&2.753~$\times 10^{-14} \times  (315614/{\rm Tg})^{1.5}
\times (1+(115188/{\rm Tg})^{0.407})^{-2.242}$&b, case B\\
H2+ + e$\rightarrow$ H + H&10$^{-8}$ if Tg $<$ 617~K&\\
&1.32$^{-6}\times {\rm Tg}^{-0.76}$ if Tg $>$ 617~K&a\\
HD+ + e$\rightarrow$H + D&7.2~$\times 10^{-8}\times {\rm Tg}^{-0.5}$&a\\
H + e $\rightarrow$ H- + phot&dex$(-17.845+0.762\times  \log({\rm Tg}+0.1523 \times
(\log({\rm Tg}))^2-0.03274 \times  \log({\rm Tg})^3)$&a\\
D + e $\rightarrow$ D- + phot&dex$(-17.845+0.762 \times  \log({\rm Tg})+0.1523
\times
(\log({\rm Tg}))^2-0.03274 \times  \log({\rm Tg})^3)$&a\\
H + e $\rightarrow$  H+ + e +
e&$\exp(-3.271396\times 10+1.3536\times 10\times \ln({\rm Te})-5.7393\times
\ln({\rm Te})^2+1.5631\times \ln({\rm Te})^3)$ &a\\
D + e $\rightarrow$  D+ + e +
e&$\exp(-3.271396\times 10+1.3536\times 10\times \ln({\rm Te})-5.7393\times
\ln({\rm Te})^2+1.5631\times \ln({\rm Te})^3)$ &a\\
H- + H $\rightarrow$ H2 + e (higher value)&$5\times  10^{-9}  $&b\\
H- + H $\rightarrow$ H2 + e (lower value) &$0.65\times  10^{-9}$&b\\
D- + H $\rightarrow$ HD + e(higher value)&$0.5 \times  5\times  10^{-9}$&b\\
D- + H $\rightarrow$ HD + e(lower value)&$0.5 \times  0.65\times
10^{-9}$&b\\
H- + D $\rightarrow$ HD + e(higher value)&$0.5 \times  5\times  10^{-9}$&b\\
H- + D $\rightarrow$ HD + e(lower value)&$0.5 \times  0.65\times
10^{-9}$&b\\
D- + D $\rightarrow$ D2 + e (higher value)&$5\times  10^{-9} $ &b\\
D- + D $\rightarrow$ D2 + e (lower value) &$0.65\times  10^{-9}$&b\\
H+ + D- $\rightarrow$ HD+ + e& $1.1\times  10^{9}\times ({\rm Tg}/300)^{-0.4}$&a\\
D+ + H- $\rightarrow$ HD+ + e& $1.1\times  10^{9}\times ({\rm Tg}/300)^{-0.4}$&a\\
\hline 
\end{tabular}}
\par
 \smallskip
 {$^a$ Glover \& Savin (2008); $^b$ Abel \& Glover (2008); $^c$ Walmsley et~al. 2004}.
\par
\end{table}