\begin{table}%t1
%\centering
\par
\caption{Summary of the model atom used in our calculations.
$N_{\hbox{\sc f}}$ is the number of full levels, $N_{\hbox{\sc s}}$ the number
of super levels and $N_{\hbox{\sc t}}$ the corresponding number of
transitions.\label{tab1}}
\label{tabatom}
\begin{tabular}{
l@{\hspace{0mm}}
c@{\hspace{0.5mm}}c@{\hspace{0.5mm}}cc@{\hspace{0.5mm}}c@{\hspace{0.5mm}}cc@{\hspace{0.5mm}}c@{\hspace{0.5mm}}c
c@{\hspace{0.5mm}}c@{\hspace{0.5mm}}c}
\hline
\hline
& \multicolumn{3}{c}{I   } &
  \multicolumn{3}{c}{II  } &
  \multicolumn{3}{c}{III } &
  \multicolumn{3}{c}{IV  } \\
\par
Ion          &
$N_{\hbox{\sc f}}$  &  $N_{\hbox{\sc s}}$ & $N_{\hbox{\sc t}}$ &
$N_{\hbox{\sc f}}$  &  $N_{\hbox{\sc s}}$ & $N_{\hbox{\sc t}}$ &
$N_{\hbox{\sc f}}$  &  $N_{\hbox{\sc s}}$ & $N_{\hbox{\sc t}}$ &
$N_{\hbox{\sc f}}$  &  $N_{\hbox{\sc s}}$ & $N_{\hbox{\sc t}}$ \\
\hline
 H  & 30 & 20 &     \\
 He & 51 & 40 & 255& 5  &  5 & 10  \\
  C &    &    &    & 59 & 32 &334  & 20 & 12 & 49 & 14 & 9 & 46 \\
  N & 104& 44 & 760& 41 & 23 &144  &  8 &  8 & 11    \\
  O &  75& 23 & 535&111 & 30 &1093 & 46 & 26 & 184    \\
 Ne &    &    &    &242 & 42 &5397 \\
 Na &  71& 22 & 788& 35 & 21 & 181 \\
 Mg &    &    &    & 65 & 22 &1229 \\
 Al &    &    &    & 44 & 26 & 156 & 45 & 17 &337    \\
 Si &    &    &    & 59 & 31 & 318 & 51 & 27 &235    \\
  S &    &    &    &324 & 56 &7830 & 98 & 48 &832    \\
 Ca &    &    &    & 77 & 21 & 1464  \\
 Ti &    &    &    &152 & 37 &3068 & 206 & 33 &4584  \\
 Cr &    &    &    &196 & 28 &3580 & 145 & 30 &2359  \\
 Mn &    &    &    & 97 & 25 & 210 & 175 & 30 &3173  \\
 Fe &    &    &    &827 &265 &43077& 477 & 61 &6411 & 282 & 50 & 7872 \\
 Co &    &    &    &144 & 34 &2047 & 283 & 41 &6910   \\
 Ni &    &    &    &93  & 19 & 817 & 67  & 15 & 379   \\
\hline
\end{tabular}
\end{table}