\begin{table}%t1
\caption{\label{FitCoeff}Fit coefficients for the $n_{{\rm cutoff}}$ and field-ionization-free plasma DR~rate coefficients of \ion{S}{vi} and \ion{Ar}{viii}. The dimensions of $c_{i}$ and $E_{i}$ are $\rm{cm}^{3}~\rm{s}^{-1}~\rm{K}^{1.5}$ and~eV, respectively. Numbers in the square brackets are powers of~10.}             
%\centering
\small         
\begin{tabular}{lrrrr}        
\hline\hline                 
\ion{S}{vi} &$n_{{\rm cutoff}}$&~~~~~~~~   &$n=1000$   \\       
$i$    &$c_{i}$      & $E_{i}$ & $c_{i}$       & $E_{i}$  \\
\hline
1  & 1.75 [--7]     &  2.74 [--2]  &   2.40  [--7]   & 5.00 [--2]\\  
2  & 4.54 [--6]      &  3.55 [--1]   &   5.41  [--6]   & 3.87 [--1] \\
3  & 4.20 [--5]      &  9.80 [--1]    &   4.76  [--5]    &  1.04  ~[0]\\
4  & 1.44 [--4]	    &  2.19 [0]    &   1.63  [--4]    &  2.37  ~[0]\\
5  &	8.75	[--4]    & 5.48  ~[0]    &   1.10   [--3]    &  5.97 ~[0]\\
6  &  7.18 [--3]      & 1.17~[1]     &   3.19   [--2]   &  1.29 ~[1]\\
\hline                  
\ion{Ar}{viii} &$n_{{\rm cutoff}}$&~~~~~~~~   &$n=1000$   \\       
$i$    &$c_{i}$      & $E_{i}$ & $c_{i}$       & $E_{i}$  \\
\hline
1  &  8.28 [--6]     & 2.80   [--2]  &  8.33   [--6]   & 2.80 [--2]\\  
2  &  1.13 [--4]     & 8.40   [--1]  &  1.16    [--4]   &  8.49 [--1]\\
3  &  2.55 [--4]     & 2.21  ~[0]  &  2.89    [--4]   &  2.33 ~[0]\\
4  & 	1.75 [--3]	    & 5.59  ~[0]  &  1.95   [--3]   & 5.88  ~[0]\\
5  &	1.87 [--2]   	& 1.47  ~[1]  &  5.28  [--2]   & 1.63  ~[1]\\
6  &  3.00 [--3]     &  3.50 ~[1]  &  4.90   [--3]   &  3.00 ~[1]\\
\hline
\end{tabular}
\end{table}