\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}