\begin{table}%t10
%\centering
\par
\caption{\label{tab_energy_ni}The level energies (Ryd) of Ni$^{18+}$ from different calculations along with the compilation of NIST v3. }
\begin{tabular}{ccccccc}
\hline\hline\noalign{\smallskip}
ID  &   Level~specification  & NIST\tablefootmark{a} & AS   & FAC   & GRASP\tablefootmark{b} & CHIANTI\tablefootmark{c}  \\
\hline\noalign{\smallskip}
   1 & ${\rm     2s^2 2p^6 ~ ^1S_0}$ &            & 0.00000    &                & 0.0000   &            \\
   2 & ${\rm  2s^2 2p^5 3s ~ ^3P_2}$ &   64.7479  & 64.7742    &   64.6221      & 64.6011  &   64.7263  \\
   3 & ${\rm  2s^2 2p^5 3s ~ ^1P_1}$ &   64.9059  & 64.9287    &   64.7897      & 64.7640  &   64.8740  \\
   4 & ${\rm  2s^2 2p^5 3s ~ ^3P_0}$ &   66.0459  & 66.0775    &   65.9187      & 65.9039  &   66.0385  \\
   5 & ${\rm  2s^2 2p^5 3s ~ ^3P_1}$ &   66.1407  & 66.1706    &   66.0193      & 66.0009  &   66.1251  \\
   6 & ${\rm  2s^2 2p^5 3p ~ ^3S_1}$ &   67.2696  & 67.3214    &   67.1650      & 67.1257  &   67.3018  \\
   7 & ${\rm  2s^2 2p^5 3p ~ ^3D_2}$ &   67.5241  & 67.5856    &   67.4291      & 67.3913  &   67.5202  \\
   8 & ${\rm  2s^2 2p^5 3p ~ ^3D_3}$ &   67.7229  & 67.7786    &   67.6269      & 67.5876  &   67.7173  \\
   9 & ${\rm  2s^2 2p^5 3p ~ ^1P_1}$ &   67.7987  & 67.8544    &   67.7073      & 67.6682  &   67.7830  \\
  10 & ${\rm  2s^2 2p^5 3p ~ ^3P_2}$ &   67.9647  & 68.0153    &   67.8694      & 67.8324  &   67.9334  \\
  11 & ${\rm  2s^2 2p^5 3p ~ ^3P_0}$ &   68.4879  & 68.5694    &   68.4048      & 68.3717  &   68.4646  \\
  12 & ${\rm  2s^2 2p^5 3p ~ ^3D_1}$ &   68.7711  & 68.8455    &   68.6775      & 68.6441  &   68.7870  \\
  13 & ${\rm  2s^2 2p^5 3p ~ ^3P_1}$ &   69.1003  & 69.1570    &   69.0003      & 68.9678  &   69.0941  \\
  14 & ${\rm  2s^2 2p^5 3p ~ ^1D_2}$ &   69.1402  & 69.2008    &   69.0411      & 69.0097  &   69.1369  \\
  15 & ${\rm  2s^2 2p^5 3p ~ ^1S_0}$ &   70.0837  & 70.2499    &   70.1372      & 70.1203  &   70.0599  \\
  16 & ${\rm  2s^2 2p^5 3d ~ ^3P_0}$ &   71.0603  & 71.1264    &   70.9484      & 70.9199  &   71.0761  \\
  17 & ${\rm  2s^2 2p^5 3d ~ ^3P_1}$ &   71.1490  & 71.2239    &   71.0377      & 71.0093  &   71.1644  \\
  18 & ${\rm  2s^2 2p^5 3d ~ ^3P_2}$ &   71.3137  & 71.4019    &   71.2055      & 71.1776  &   71.3240  \\
  19 & ${\rm  2s^2 2p^5 3d ~ ^3F_4}$ &   71.3092  & 71.4096    &   71.2029      & 71.1752  &   71.3248  \\
  20 & ${\rm  2s^2 2p^5 3d ~ ^3F_3}$ &   71.3607  & 71.4437    &   71.2575      & 71.2340  &   71.3676  \\
  21 & ${\rm  2s^2 2p^5 3d ~ ^1D_2}$ &   71.5080  & 71.5928    &   71.4098      & 71.3861  &   71.4998  \\
  22 & ${\rm  2s^2 2p^5 3d ~ ^3D_3}$ &   71.6041  & 71.7083    &   71.5079      & 71.4847  &   71.5973  \\
  23 & ${\rm  2s^2 2p^5 3d ~ ^3D_1}$ &   72.0028  & 72.1387    &   71.9452      & 71.9256  &   72.0192  \\
  24 & ${\rm  2s^2 2p^5 3d ~ ^3F_2}$ &   72.6505  & 72.7348    &   72.5485      & 72.5263  &   72.6617  \\
  25 & ${\rm  2s^2 2p^5 3d ~ ^3D_2}$ &   72.7265  & 72.8272    &   72.6191      & 72.6005  &   72.7346  \\
  26 & ${\rm  2s^2 2p^5 3d ~ ^1F_3}$ &   72.7796  & 72.8836    &   72.6726      & 72.6564  &   72.7920  \\
  27 & ${\rm  2s^2 2p^5 3d ~ ^1P_1}$ &   73.2823  & 73.4547    &   73.2548      & 73.2464  &   73.3387  \\
  28 & ${\rm   2s 2p^6 3s  ~ ^3S_1}$ &   76.1637  & 76.0905    &   75.9685      & 75.9179  &   76.0394  \\
  29 & ${\rm   2s 2p^6 3s  ~ ^1S_0}$ &   76.6922  & 76.6420    &   76.5136      & 76.4612  &   76.5453  \\
  30 & ${\rm   2s 2p^6 3p  ~ ^3P_0}$ &            & 78.8035    &   78.6856      & 78.6288  &   78.7562  \\
  31 & ${\rm   2s 2p^6 3p  ~ ^3P_1}$ &   78.5640  & 78.8478    &   78.7275      & 78.6701  &   78.7972  \\
  32 & ${\rm   2s 2p^6 3p  ~ ^3P_2}$ &            & 79.1025    &   78.9785      & 78.9231  &   79.0459  \\
  33 & ${\rm   2s 2p^6 3p  ~ ^1P_1}$ &   78.9731  & 79.2543    &   79.1374      & 79.0767  &   79.1836  \\
  34 & ${\rm   2s 2p^6 3d  ~ ^3D_1}$ &            & 82.5614    &   82.4049      & 82.3630  &   82.5247  \\
  35 & ${\rm   2s 2p^6 3d  ~ ^3D_2}$ &            & 82.5888    &   82.4203      & 82.3787  &   82.5451  \\
  36 & ${\rm   2s 2p^6 3d  ~ ^3D_3}$ &            & 82.6376    &   82.4501      & 82.4089  &   82.5807  \\
  37 & ${\rm   2s 2p^6 3d  ~ ^1D_2}$ &            & 83.0283    &   82.8611      & 82.8349  &   82.9545  \\
  38 & ${\rm  2s^2 2p^5 4s ~ ^3P_2}$ &            & 87.4340    &   87.2557      & 87.1882  &   87.3495  \\
  39 & ${\rm  2s^2 2p^5 4s ~ ^1P_1}$ &   87.3449  & 87.4794    &   87.3103      & 87.2418  &   87.3995  \\
  40 & ${\rm  2s^2 2p^5 4p ~ ^3S_1}$ &            & 88.4761    &   88.3083      & 88.2410  &   88.4117  \\
  41 & ${\rm  2s^2 2p^5 4p ~ ^3D_2}$ &            & 88.5396    &   88.3755      & 88.3064  &   88.4710  \\
  42 & ${\rm  2s^2 2p^5 4p ~ ^3D_3}$ &            & 88.6148    &   88.4565      & 88.3882  &   88.5530  \\
  43 & ${\rm  2s^2 2p^5 4p ~ ^1P_1}$ &            & 88.6414    &   88.4864      & 88.4172  &   88.5784  \\
  44 & ${\rm  2s^2 2p^5 4p ~ ^3P_2}$ &            & 88.6935    &   88.5414      & 88.4719  &   88.6285  \\
  45 & ${\rm  2s^2 2p^5 4s ~ ^3P_0}$ &            & 88.7381    &   88.5592      & 88.4959  &   88.6644  \\
  46 & ${\rm  2s^2 2p^5 4s ~ ^3P_1}$ &   88.6207  & 88.7610    &   88.5863      & 88.5223  &   88.6908  \\
  47 & ${\rm  2s^2 2p^5 4p ~ ^3P_0}$ &            & 89.0180    &   88.8778      & 88.8116  &   88.9147  \\
  48 & ${\rm  2s^2 2p^5 4p ~ ^3D_1}$ &            & 89.8241    &   89.6556      & 89.5915  &   89.7666  \\
  49 & ${\rm  2s^2 2p^5 4d ~ ^3P_0}$ &            & 89.8633    &   89.6923      & 89.6308  &   89.8053  \\
  50 & ${\rm  2s^2 2p^5 4d ~ ^3P_1}$ &   89.7142  & 89.9037    &   89.7307      & 89.6695  &   89.8418  \\
  51 & ${\rm  2s^2 2p^5 4p ~ ^3P_1}$ &            & 89.9367    &   89.7797      & 89.7152  &   89.8858  \\
  52 & ${\rm  2s^2 2p^5 4p ~ ^1D_2}$ &            & 89.9566    &   89.7997      & 89.7347  &   89.9049  \\
  53 & ${\rm  2s^2 2p^5 4d ~ ^3F_4}$ &   89.8783  & 89.9595    &   89.7800      & 89.7186  &   89.8919  \\
  54 & ${\rm  2s^2 2p^5 4d ~ ^3F_3}$ &   89.8974  & 89.9696    &   89.7988      & 89.7381  &   89.9055  \\
  55 & ${\rm  2s^2 2p^5 4d ~ ^3P_2}$ &            & 89.9698    &   89.7945      & 89.7335  &   89.9028  \\
  56 & ${\rm  2s^2 2p^5 4d ~ ^1D_2}$ &            & 90.0223    &   89.8526      & 89.7923  &   89.9538  \\
  57 & ${\rm  2s^2 2p^5 4d ~ ^3D_3}$ &            & 90.0641    &   89.8883      & 89.8282  &   89.9894  \\
  58 & ${\rm  2s^2 2p^5 4p ~ ^1S_0}$ &            & 90.1459    &   90.0186      & 89.9571  &   90.0498  \\
  59 & ${\rm  2s^2 2p^5 4d ~ ^1P_1}$ &   90.1334  & 90.2812    &   90.1093      & 90.0559  &   90.1881  \\
  60 & ${\rm  2s^2 2p^5 4f ~ ^3D_1}$ &            & 90.6112    &   90.4620      & 90.3808  &   90.5167  \\
  \hline
\end{tabular}
\tablefoot{{\tablefootmark{a} Sources of the NIST v3 are from the work of %Sugar \& Corliss 
\citet{SC85} and references therein.} \tablefootmark{b}{GRASP data are from the work of %Aggarwal \& Keenan (
\citet{AK06}.} \tablefoottext{c}{Data in CHIANTI are from the work of %Zhang et~al. (
\citet{ZSC87}.}}
\end{table}