Table 1: Target levels of K XIV and Sc XVI, and their threshold energies (in Ryd).
K XIV Sc XVI

Index Configuration Level Expt.^a GRASP Configuration Level Expt.^a GRASP

1...... 1s²2s²2p² ³P₀ 0.0000 0.0000 1s²2s²2p² ³P₀ 0.0000 0.0000

2...... 1s²2s²2p² ³P₁ 0.1206 0.1196 1s²2s²2p² ³P₁ 0.2092 0.2076

3...... 1s²2s²2p² ³P₂ 0.2572 0.2564 1s²2s²2p² ³P₂ 0.4103 0.4099

4...... 1s²2s²2p² ¹D₂ 0.8740 0.9017 1s²2s²2p² ¹D₂ 1.1241 1.1495

5...... 1s²2s²2p² ¹S₀ 1.6304 1.6390 1s²2s²2p² ¹S₀ 1.9931 1.9996

6...... 1s²2s2p³ ⁵S ${^{\circ}}{_2}$ 2.2840 2.2160 1s²2s2p³ ⁵S ${^{\circ}}{_2}$ 2.7460 2.6986

7...... 1s²2s2p³ ³D ${^{\circ}}{_2}$ 4.1805 4.2224 1s²2s2p³ ³D ${^{\circ}}{_2}$ 4.8899 4.9325

8...... 1s²2s2p³ ³D ${^{\circ}}{_1}$ 4.1873 4.2293 1s²2s2p³ ³D ${^{\circ}}{_1}$ 4.9000 4.9433

9...... 1s²2s2p³ ³D ${^{\circ}}{_3}$ 4.2010 4.2413 1s²2s2p³ ³D ${^{\circ}}{_3}$ 4.9393 4.9800

10...... 1s²2s2p³ ³P ${^{\circ}}{_0}$ 4.8972 4.9500 1s²2s2p³ ³P ${^{\circ}}{_0}$ 5.7280 5.7816

11...... 1s²2s2p³ ³P ${^{\circ}}{_1}$ 4.9029 4.9556 1s²2s2p³ ³P ${^{\circ}}{_1}$ 5.7432 5.7965

12...... 1s²2s2p³ ³P ${^{\circ}}{_2}$ 4.9203 4.9722 1s²2s2p³ ³P ${^{\circ}}{_2}$ 5.7813 5.8332

13...... 1s²2s2p³ ³S ${^{\circ}}{_1}$ 6.1757 6.2936 1s²2s2p³ ³S ${^{\circ}}{_1}$ 7.1293 7.2478

14...... 1s²2s2p³ ¹D ${^{\circ}}{_2}$ 6.1643 6.2994 1s²2s2p³ ¹D ${^{\circ}}{_2}$ 7.1601 7.2941

15...... 1s²2s2p³ ¹P ${^{\circ}}{_1}$ 6.8805 7.0246 1s²2s2p³ ¹P ${^{\circ}}{_1}$ 7.9900 8.1345

16...... 1s²2p⁴ ³P₂ 9.3869 9.5251 1s²2p⁴ ³P₂ 10.824 10.9652

17...... 1s²2p⁴ ³P₁ 9.5740 9.7092 1s²2p⁴ ³P₁ 11.129 11.2655

18...... 1s²2p⁴ ³P₀ 9.6248 9.7608 1s²2p⁴ ³P₀ 11.188 11.3278

19...... 1s²2p⁴ ¹D₂ 10.104 10.2920 1s²2p⁴ ¹D₂ 11.714 11.9019

20...... 1s²2p⁴ ¹S₀ 11.435 11.6672 1s²2p⁴ ¹S₀ 13.226 13.4574

21...... 1s²2s²2p3s ³P ${^{\circ}}{_0}$ ...... 32.6831 1s²2s²2p3s ³P ${^{\circ}}{_0}$ ...... 41.8443

22...... 1s²2s²2p3s ³P ${^{\circ}}{_1}$ ...... 32.7250 1s²2s²2p3s ³P ${^{\circ}}{_1}$ 41.970 41.8981

23...... 1s²2s²2p3s ³P ${^{\circ}}{_2}$ ...... 32.9437 1s²2s²2p3s ³P ${^{\circ}}{_2}$ 42.330 42.2547

24...... 1s²2s²2p3s ¹P ${^{\circ}}{_1}$ ...... 33.1109 1s²2s²2p3s ¹P ${^{\circ}}{_1}$ 42.490 42.4381

25...... 1s²2s²2p3p ¹P₁ ...... 33.7630 1s²2s²2p3p ³D₁ ...... 43.0839

26...... 1s²2s²2p3p ³D₁ ...... 33.9296 1s²2s²2p3p ¹P₁ ...... 43.3261

27...... 1s²2s²2p3p ³D₂ ...... 33.9419 1s²2s²2p3p ³D₂ ...... 43.3370

28...... 1s²2s²2p3p ³P₀ ...... 34.1207 1s²2s²2p3p ³P₀ ...... 43.5175

29...... 1s²2s²2p3p ³D₃ ...... 34.1253 1s²2s²2p3p ³P₁ ...... 43.6380

30...... 1s²2s²2p3p ³S₁ ...... 34.1557 1s²2s²2p3p ³D₃ ...... 43.6360

31...... 1s²2s²2p3p ³P₁ ...... 34.2616 1s²2s²2p3p ³S₁ ...... 43.7675

32...... 1s²2s²2p3p ³P₂ ...... 34.3046 1s²2s²2p3p ³P₂ ...... 43.8172

33...... 1s²2s²2p3p ¹D₂ ...... 34.6637 1s²2s²2p3p ¹D₂ ...... 44.2242

34...... 1s²2s²2p3p ¹S₀ ...... 35.0815 1s²2s²2p3d ³F ${^{\circ}}{_2}$ 44.000 44.6449

35...... 1s²2s²2p3d ³F ${^{\circ}}{_2}$ ...... 35.1118 1s²2s²2p3p ¹S₀ ...... 44.6965

36...... 1s²2s²2p3d ³F ${^{\circ}}{_3}$ 35.281 35.2249 1s²2s²2p3d ³F ${^{\circ}}{_3}$ ...... 44.8108

37...... 1s²2s²2p3d ¹D ${^{\circ}}{_2}$ ...... 35.2784 1s²2s²2p3d ¹D ${^{\circ}}{_2}$ ...... 44.8758

38...... 1s²2s²2p3d ³F ${^{\circ}}{_4}$ ...... 35.3805 1s²2s²2p3d ³D ${^{\circ}}{_1}$ 45.070 45.0389

39...... 1s²2s²2p3d ³D ${^{\circ}}{_1}$ ...... 35.4403 1s²2s²2p3d ³F ${^{\circ}}{_4}$ ...... 45.0710

40...... 1s²2s²2p3d ³D ${^{\circ}}{_2}$ 35.540 35.5013 1s²2s²2p3d ³D ${^{\circ}}{_2}$ 45.100 45.1766

41...... 1s²2s²2p3d ³D ${^{\circ}}{_3}$ 35.646 35.5992 1s²2s²2p3d ³D ${^{\circ}}{_3}$ 45.330 45.3115

42...... 1s²2s²2p3d ³P ${^{\circ}}{_2}$ 35.715 35.6591 1s²2s²2p3d ³P ${^{\circ}}{_2}$ 45.400 45.3875

43...... 1s²2s²2p3d ³P ${^{\circ}}{_1}$ ...... 35.6754 1s²2s²2p3d ³P ${^{\circ}}{_1}$ 45.430 45.4037

44...... 1s²2s²2p3d ³P ${^{\circ}}{_0}$ ...... 35.6872 1s²2s²2p3d ³P ${^{\circ}}{_0}$ ...... 45.4177

45...... 1s²2s²2p3d ¹P ${^{\circ}}{_1}$ 36.075 36.0297 1s²2s²2p3d ¹P ${^{\circ}}{_1}$ 45.820 45.8118

46...... 1s²2s²2p3d ¹F ${^{\circ}}{_3}$ 36.046 36.0519 1s²2s²2p3d ¹F ${^{\circ}}{_3}$ 45.810 45.8299

**Table 1:** Target levels of K XIV and Sc XVI, and their threshold energies (in Ryd).
	K XIV	Sc XVI
Index	Configuration	Level	Expt.^a	GRASP	Configuration	Level	Expt.^a	GRASP
1......	1s²2s²2p²	³P₀	0.0000	0.0000	1s²2s²2p²	³P₀	0.0000	0.0000
2......	1s²2s²2p²	³P₁	0.1206	0.1196	1s²2s²2p²	³P₁	0.2092	0.2076
3......	1s²2s²2p²	³P₂	0.2572	0.2564	1s²2s²2p²	³P₂	0.4103	0.4099
4......	1s²2s²2p²	¹D₂	0.8740	0.9017	1s²2s²2p²	¹D₂	1.1241	1.1495
5......	1s²2s²2p²	¹S₀	1.6304	1.6390	1s²2s²2p²	¹S₀	1.9931	1.9996
6......	1s²2s2p³	⁵S ${^{\circ}}{_2}$	2.2840	2.2160	1s²2s2p³	⁵S ${^{\circ}}{_2}$	2.7460	2.6986
7......	1s²2s2p³	³D ${^{\circ}}{_2}$	4.1805	4.2224	1s²2s2p³	³D ${^{\circ}}{_2}$	4.8899	4.9325
8......	1s²2s2p³	³D ${^{\circ}}{_1}$	4.1873	4.2293	1s²2s2p³	³D ${^{\circ}}{_1}$	4.9000	4.9433
9......	1s²2s2p³	³D ${^{\circ}}{_3}$	4.2010	4.2413	1s²2s2p³	³D ${^{\circ}}{_3}$	4.9393	4.9800
10......	1s²2s2p³	³P ${^{\circ}}{_0}$	4.8972	4.9500	1s²2s2p³	³P ${^{\circ}}{_0}$	5.7280	5.7816
11......	1s²2s2p³	³P ${^{\circ}}{_1}$	4.9029	4.9556	1s²2s2p³	³P ${^{\circ}}{_1}$	5.7432	5.7965
12......	1s²2s2p³	³P ${^{\circ}}{_2}$	4.9203	4.9722	1s²2s2p³	³P ${^{\circ}}{_2}$	5.7813	5.8332
13......	1s²2s2p³	³S ${^{\circ}}{_1}$	6.1757	6.2936	1s²2s2p³	³S ${^{\circ}}{_1}$	7.1293	7.2478
14......	1s²2s2p³	¹D ${^{\circ}}{_2}$	6.1643	6.2994	1s²2s2p³	¹D ${^{\circ}}{_2}$	7.1601	7.2941
15......	1s²2s2p³	¹P ${^{\circ}}{_1}$	6.8805	7.0246	1s²2s2p³	¹P ${^{\circ}}{_1}$	7.9900	8.1345
16......	1s²2p⁴	³P₂	9.3869	9.5251	1s²2p⁴	³P₂	10.824	10.9652
17......	1s²2p⁴	³P₁	9.5740	9.7092	1s²2p⁴	³P₁	11.129	11.2655
18......	1s²2p⁴	³P₀	9.6248	9.7608	1s²2p⁴	³P₀	11.188	11.3278
19......	1s²2p⁴	¹D₂	10.104	10.2920	1s²2p⁴	¹D₂	11.714	11.9019
20......	1s²2p⁴	¹S₀	11.435	11.6672	1s²2p⁴	¹S₀	13.226	13.4574
21......	1s²2s²2p3s	³P ${^{\circ}}{_0}$	......	32.6831	1s²2s²2p3s	³P ${^{\circ}}{_0}$	......	41.8443
22......	1s²2s²2p3s	³P ${^{\circ}}{_1}$	......	32.7250	1s²2s²2p3s	³P ${^{\circ}}{_1}$	41.970	41.8981
23......	1s²2s²2p3s	³P ${^{\circ}}{_2}$	......	32.9437	1s²2s²2p3s	³P ${^{\circ}}{_2}$	42.330	42.2547
24......	1s²2s²2p3s	¹P ${^{\circ}}{_1}$	......	33.1109	1s²2s²2p3s	¹P ${^{\circ}}{_1}$	42.490	42.4381
25......	1s²2s²2p3p	¹P₁	......	33.7630	1s²2s²2p3p	³D₁	......	43.0839
26......	1s²2s²2p3p	³D₁	......	33.9296	1s²2s²2p3p	¹P₁	......	43.3261
27......	1s²2s²2p3p	³D₂	......	33.9419	1s²2s²2p3p	³D₂	......	43.3370
28......	1s²2s²2p3p	³P₀	......	34.1207	1s²2s²2p3p	³P₀	......	43.5175
29......	1s²2s²2p3p	³D₃	......	34.1253	1s²2s²2p3p	³P₁	......	43.6380
30......	1s²2s²2p3p	³S₁	......	34.1557	1s²2s²2p3p	³D₃	......	43.6360
31......	1s²2s²2p3p	³P₁	......	34.2616	1s²2s²2p3p	³S₁	......	43.7675
32......	1s²2s²2p3p	³P₂	......	34.3046	1s²2s²2p3p	³P₂	......	43.8172
33......	1s²2s²2p3p	¹D₂	......	34.6637	1s²2s²2p3p	¹D₂	......	44.2242
34......	1s²2s²2p3p	¹S₀	......	35.0815	1s²2s²2p3d	³F ${^{\circ}}{_2}$	44.000	44.6449
35......	1s²2s²2p3d	³F ${^{\circ}}{_2}$	......	35.1118	1s²2s²2p3p	¹S₀	......	44.6965
36......	1s²2s²2p3d	³F ${^{\circ}}{_3}$	35.281	35.2249	1s²2s²2p3d	³F ${^{\circ}}{_3}$	......	44.8108
37......	1s²2s²2p3d	¹D ${^{\circ}}{_2}$	......	35.2784	1s²2s²2p3d	¹D ${^{\circ}}{_2}$	......	44.8758
38......	1s²2s²2p3d	³F ${^{\circ}}{_4}$	......	35.3805	1s²2s²2p3d	³D ${^{\circ}}{_1}$	45.070	45.0389
39......	1s²2s²2p3d	³D ${^{\circ}}{_1}$	......	35.4403	1s²2s²2p3d	³F ${^{\circ}}{_4}$	......	45.0710
40......	1s²2s²2p3d	³D ${^{\circ}}{_2}$	35.540	35.5013	1s²2s²2p3d	³D ${^{\circ}}{_2}$	45.100	45.1766
41......	1s²2s²2p3d	³D ${^{\circ}}{_3}$	35.646	35.5992	1s²2s²2p3d	³D ${^{\circ}}{_3}$	45.330	45.3115
42......	1s²2s²2p3d	³P ${^{\circ}}{_2}$	35.715	35.6591	1s²2s²2p3d	³P ${^{\circ}}{_2}$	45.400	45.3875
43......	1s²2s²2p3d	³P ${^{\circ}}{_1}$	......	35.6754	1s²2s²2p3d	³P ${^{\circ}}{_1}$	45.430	45.4037
44......	1s²2s²2p3d	³P ${^{\circ}}{_0}$	......	35.6872	1s²2s²2p3d	³P ${^{\circ}}{_0}$	......	45.4177
45......	1s²2s²2p3d	¹P ${^{\circ}}{_1}$	36.075	36.0297	1s²2s²2p3d	¹P ${^{\circ}}{_1}$	45.820	45.8118
46......	1s²2s²2p3d	¹F ${^{\circ}}{_3}$	36.046	36.0519	1s²2s²2p3d	¹F ${^{\circ}}{_3}$	45.810	45.8299

^a NIST.

Table 2: Target levels of Ti XVII and V XVIII, and their threshold energies (in Ryd).
Ti XVII V XVIII

Index Configuration Level Expt.^a GRASP Configuration Level Expt.^a GRASP

1...... 1s²2s²2p² ³P₀ 0.0000 0.0000 1s²2s²2p² ³P₀ 0.0000 0.0000

2...... 1s²2s²2p² ³P₁ 0.2703 0.2683 1s²2s²2p² ³P₁ 0.3450 0.3427

3...... 1s²2s²2p² ³P₂ 0.5070 0.5078 1s²2s²2p² ³P₂ 0.6210 0.6216

4...... 1s²2s²2p² ¹D₂ 1.2817 1.3057 1s²2s²2p² ¹D₂ 1.4663 1.4888

5...... 1s²2s²2p² ¹S₀ 2.2069 2.2141 1s²2s²2p² ¹S₀ 2.4500 2.4565

6...... 1s²2s2p³ ⁵S ${^{\circ}}{_2}$ 3.0405 2.9745 1s²2s2p³ ⁵S ${^{\circ}}{_2}$ 3.3439 3.2770

7...... 1s²2s2p³ ³D ${^{\circ}}{_2}$ 5.2752 5.3180 1s²2s2p³ ³D ${^{\circ}}{_2}$ 5.6850 5.7271

8...... 1s²2s2p³ ³D ${^{\circ}}{_1}$ 5.2863 5.3304 1s²2s2p³ ³D ${^{\circ}}{_1}$ 5.6957 5.7402

9...... 1s²2s2p³ ³D ${^{\circ}}{_3}$ 5.3469 5.3878 1s²2s2p³ ³D ${^{\circ}}{_3}$ 5.7860 5.8260

10...... 1s²2s2p³ ³P ${^{\circ}}{_0}$ 6.1824 6.2364 1s²2s2p³ ³P ${^{\circ}}{_0}$ 6.6692 6.7221

11...... 1s²2s2p³ ³P ${^{\circ}}{_1}$ 6.2049 6.2588 1s²2s2p³ ³P ${^{\circ}}{_1}$ 6.7016 6.7542

12...... 1s²2s2p³ ³P ${^{\circ}}{_2}$ 6.2584 6.3107 1s²2s2p³ ³P ${^{\circ}}{_2}$ 6.7739 6.8256

13...... 1s²2s2p³ ³S ${^{\circ}}{_1}$ 7.6395 7.7588 1s²2s2p³ ³S ${^{\circ}}{_1}$ 8.1770 8.2966

14...... 1s²2s2p³ ¹D ${^{\circ}}{_2}$ 7.7014 7.8347 1s²2s2p³ ¹D ${^{\circ}}{_2}$ 8.2781 8.4102

15...... 1s²2s2p³ ¹P ${^{\circ}}{_1}$ 8.5970 8.7398 1s²2s2p³ ¹P ${^{\circ}}{_1}$ 9.2441 9.3859

16...... 1s²2p⁴ ³P₂ 11.586 11.7279 1s²2p⁴ ³P₂ 12.381 12.5239

17...... 1s²2p⁴ ³P₁ 11.967 12.1049 1s²2p⁴ ³P₁ 12.856 12.9921

18...... 1s²2p⁴ ³P₀ 12.026 12.1671 1s²2p⁴ ³P₀ 12.905 13.0481

19...... 1s²2p⁴ ¹D₂ 12.578 12.7659 1s²2p⁴ ¹D₂ 13.490 13.6767

20...... 1s²2p⁴ ¹S₀ 14.187 14.4184 1s²2p⁴ ¹S₀ 15.202 15.4332

21...... 1s²2s²2p3s ³P ${^{\circ}}{_0}$ ...... 46.8526 1s²2s²2p3s ³P ${^{\circ}}{_0}$ ...... 52.1481

22...... 1s²2s²2p3s ³P ${^{\circ}}{_1}$ 46.870 46.9122 1s²2s²2p3s ³P ${^{\circ}}{_1}$ 52.170 52.2135

23...... 1s²2s²2p3s ³P ${^{\circ}}{_2}$ 47.320 47.3586 1s²2s²2p3s ³P ${^{\circ}}{_2}$ 52.720 52.7656

24...... 1s²2s²2p3s ¹P ${^{\circ}}{_1}$ 47.000 47.5500 1s²2s²2p3s ¹P ${^{\circ}}{_1}$ 52.890 52.9651

25...... 1s²2s²2p3p ³D₁ ...... 48.1722 1s²2s²2p3p ³D₁ ...... 53.5478

26...... 1s²2s²2p3p ¹P₁ ...... 48.4584 1s²2s²2p3p ¹P₁ ...... 53.8823

27...... 1s²2s²2p3p ³D₂ ...... 48.4708 1s²2s²2p3p ³D₂ ...... 53.8979

28...... 1s²2s²2p3p ³P₀ ...... 48.6474 1s²2s²2p3p ³P₀ ...... 54.0667

29...... 1s²2s²2p3p ³P₁ ...... 48.8317 1s²2s²2p3p ³P₁ ...... 54.3316

30...... 1s²2s²2p3p ³D₃ ...... 48.8459 1s²2s²2p3p ³D₃ ...... 54.3637

31...... 1s²2s²2p3p ³S₁ ...... 48.9724 1s²2s²2p3p ³S₁ ...... 54.4834

32...... 1s²2s²2p3p ³P₂ ...... 49.0232 1s²2s²2p3p ³P₂ ...... 54.5329

33...... 1s²2s²2p3p ¹D₂ ...... 49.4567 1s²2s²2p3p ¹D₂ ...... 54.9960

34...... 1s²2s²2p3d ³F ${^{\circ}}{_2}$ 49.860 49.8455 1s²2s²2p3d ³F ${^{\circ}}{_2}$ ...... 55.3380

35...... 1s²2s²2p3p ¹S₀ ...... 49.9541 1s²2s²2p3p ¹S₀ ...... 55.5161

36...... 1s²2s²2p3d ³F ${^{\circ}}{_3}$ ...... 50.0419 1s²2s²2p3d ³F ${^{\circ}}{_3}$ ...... 55.5678

37...... 1s²2s²2p3d ¹D ${^{\circ}}{_2}$ 50.130 50.1092 1s²2s²2p3d ¹D ${^{\circ}}{_2}$ ...... 55.6347

38...... 1s²2s²2p3d ³D ${^{\circ}}{_1}$ 50.290 50.2727 1s²2s²2p3d ³D ${^{\circ}}{_1}$ ...... 55.7988

39...... 1s²2s²2p3d ³F ${^{\circ}}{_4}$ ...... 50.3724 1s²2s²2p3d ³F ${^{\circ}}{_4}$ ...... 55.9829

40...... 1s²2s²2p3d ³D ${^{\circ}}{_2}$ 50.500 50.4702 1s²2s²2p3d ³D ${^{\circ}}{_2}$ 56.100 56.0732

41...... 1s²2s²2p3d ³D ${^{\circ}}{_3}$ 50.630 50.6220 1s²2s²2p3d ³D ${^{\circ}}{_3}$ 56.260 56.2403

42...... 1s²2s²2p3d ³P ${^{\circ}}{_2}$ 50.730 50.7071 1s²2s²2p3d ³P ${^{\circ}}{_2}$ 56.380 56.3353

43...... 1s²2s²2p3d ³P ${^{\circ}}{_1}$ ...... 50.7224 1s²2s²2p3d ³P ${^{\circ}}{_1}$ 56.450 56.3488

44...... 1s²2s²2p3d ³P ${^{\circ}}{_0}$ ...... 50.7374 1s²2s²2p3d ³P ${^{\circ}}{_0}$ ...... 56.3646

45...... 1s²2s²2p3d ¹P ${^{\circ}}{_1}$ 51.140 51.1544 1s²2s²2p3d ¹P ${^{\circ}}{_1}$ ...... 56.8048

46...... 1s²2s²2p3d ¹F ${^{\circ}}{_3}$ 51.150 51.1723 1s²2s²2p3d ¹F ${^{\circ}}{_3}$ 56.800 56.8221

**Table 2:** Target levels of Ti XVII and V XVIII, and their threshold energies (in Ryd).
	Ti XVII	V XVIII
Index	Configuration	Level	Expt.^a	GRASP	Configuration	Level	Expt.^a	GRASP
1......	1s²2s²2p²	³P₀	0.0000	0.0000	1s²2s²2p²	³P₀	0.0000	0.0000
2......	1s²2s²2p²	³P₁	0.2703	0.2683	1s²2s²2p²	³P₁	0.3450	0.3427
3......	1s²2s²2p²	³P₂	0.5070	0.5078	1s²2s²2p²	³P₂	0.6210	0.6216
4......	1s²2s²2p²	¹D₂	1.2817	1.3057	1s²2s²2p²	¹D₂	1.4663	1.4888
5......	1s²2s²2p²	¹S₀	2.2069	2.2141	1s²2s²2p²	¹S₀	2.4500	2.4565
6......	1s²2s2p³	⁵S ${^{\circ}}{_2}$	3.0405	2.9745	1s²2s2p³	⁵S ${^{\circ}}{_2}$	3.3439	3.2770
7......	1s²2s2p³	³D ${^{\circ}}{_2}$	5.2752	5.3180	1s²2s2p³	³D ${^{\circ}}{_2}$	5.6850	5.7271
8......	1s²2s2p³	³D ${^{\circ}}{_1}$	5.2863	5.3304	1s²2s2p³	³D ${^{\circ}}{_1}$	5.6957	5.7402
9......	1s²2s2p³	³D ${^{\circ}}{_3}$	5.3469	5.3878	1s²2s2p³	³D ${^{\circ}}{_3}$	5.7860	5.8260
10......	1s²2s2p³	³P ${^{\circ}}{_0}$	6.1824	6.2364	1s²2s2p³	³P ${^{\circ}}{_0}$	6.6692	6.7221
11......	1s²2s2p³	³P ${^{\circ}}{_1}$	6.2049	6.2588	1s²2s2p³	³P ${^{\circ}}{_1}$	6.7016	6.7542
12......	1s²2s2p³	³P ${^{\circ}}{_2}$	6.2584	6.3107	1s²2s2p³	³P ${^{\circ}}{_2}$	6.7739	6.8256
13......	1s²2s2p³	³S ${^{\circ}}{_1}$	7.6395	7.7588	1s²2s2p³	³S ${^{\circ}}{_1}$	8.1770	8.2966
14......	1s²2s2p³	¹D ${^{\circ}}{_2}$	7.7014	7.8347	1s²2s2p³	¹D ${^{\circ}}{_2}$	8.2781	8.4102
15......	1s²2s2p³	¹P ${^{\circ}}{_1}$	8.5970	8.7398	1s²2s2p³	¹P ${^{\circ}}{_1}$	9.2441	9.3859
16......	1s²2p⁴	³P₂	11.586	11.7279	1s²2p⁴	³P₂	12.381	12.5239
17......	1s²2p⁴	³P₁	11.967	12.1049	1s²2p⁴	³P₁	12.856	12.9921
18......	1s²2p⁴	³P₀	12.026	12.1671	1s²2p⁴	³P₀	12.905	13.0481
19......	1s²2p⁴	¹D₂	12.578	12.7659	1s²2p⁴	¹D₂	13.490	13.6767
20......	1s²2p⁴	¹S₀	14.187	14.4184	1s²2p⁴	¹S₀	15.202	15.4332
21......	1s²2s²2p3s	³P ${^{\circ}}{_0}$	......	46.8526	1s²2s²2p3s	³P ${^{\circ}}{_0}$	......	52.1481
22......	1s²2s²2p3s	³P ${^{\circ}}{_1}$	46.870	46.9122	1s²2s²2p3s	³P ${^{\circ}}{_1}$	52.170	52.2135
23......	1s²2s²2p3s	³P ${^{\circ}}{_2}$	47.320	47.3586	1s²2s²2p3s	³P ${^{\circ}}{_2}$	52.720	52.7656
24......	1s²2s²2p3s	¹P ${^{\circ}}{_1}$	47.000	47.5500	1s²2s²2p3s	¹P ${^{\circ}}{_1}$	52.890	52.9651
25......	1s²2s²2p3p	³D₁	......	48.1722	1s²2s²2p3p	³D₁	......	53.5478
26......	1s²2s²2p3p	¹P₁	......	48.4584	1s²2s²2p3p	¹P₁	......	53.8823
27......	1s²2s²2p3p	³D₂	......	48.4708	1s²2s²2p3p	³D₂	......	53.8979
28......	1s²2s²2p3p	³P₀	......	48.6474	1s²2s²2p3p	³P₀	......	54.0667
29......	1s²2s²2p3p	³P₁	......	48.8317	1s²2s²2p3p	³P₁	......	54.3316
30......	1s²2s²2p3p	³D₃	......	48.8459	1s²2s²2p3p	³D₃	......	54.3637
31......	1s²2s²2p3p	³S₁	......	48.9724	1s²2s²2p3p	³S₁	......	54.4834
32......	1s²2s²2p3p	³P₂	......	49.0232	1s²2s²2p3p	³P₂	......	54.5329
33......	1s²2s²2p3p	¹D₂	......	49.4567	1s²2s²2p3p	¹D₂	......	54.9960
34......	1s²2s²2p3d	³F ${^{\circ}}{_2}$	49.860	49.8455	1s²2s²2p3d	³F ${^{\circ}}{_2}$	......	55.3380
35......	1s²2s²2p3p	¹S₀	......	49.9541	1s²2s²2p3p	¹S₀	......	55.5161
36......	1s²2s²2p3d	³F ${^{\circ}}{_3}$	......	50.0419	1s²2s²2p3d	³F ${^{\circ}}{_3}$	......	55.5678
37......	1s²2s²2p3d	¹D ${^{\circ}}{_2}$	50.130	50.1092	1s²2s²2p3d	¹D ${^{\circ}}{_2}$	......	55.6347
38......	1s²2s²2p3d	³D ${^{\circ}}{_1}$	50.290	50.2727	1s²2s²2p3d	³D ${^{\circ}}{_1}$	......	55.7988
39......	1s²2s²2p3d	³F ${^{\circ}}{_4}$	......	50.3724	1s²2s²2p3d	³F ${^{\circ}}{_4}$	......	55.9829
40......	1s²2s²2p3d	³D ${^{\circ}}{_2}$	50.500	50.4702	1s²2s²2p3d	³D ${^{\circ}}{_2}$	56.100	56.0732
41......	1s²2s²2p3d	³D ${^{\circ}}{_3}$	50.630	50.6220	1s²2s²2p3d	³D ${^{\circ}}{_3}$	56.260	56.2403
42......	1s²2s²2p3d	³P ${^{\circ}}{_2}$	50.730	50.7071	1s²2s²2p3d	³P ${^{\circ}}{_2}$	56.380	56.3353
43......	1s²2s²2p3d	³P ${^{\circ}}{_1}$	......	50.7224	1s²2s²2p3d	³P ${^{\circ}}{_1}$	56.450	56.3488
44......	1s²2s²2p3d	³P ${^{\circ}}{_0}$	......	50.7374	1s²2s²2p3d	³P ${^{\circ}}{_0}$	......	56.3646
45......	1s²2s²2p3d	¹P ${^{\circ}}{_1}$	51.140	51.1544	1s²2s²2p3d	¹P ${^{\circ}}{_1}$	......	56.8048
46......	1s²2s²2p3d	¹F ${^{\circ}}{_3}$	51.150	51.1723	1s²2s²2p3d	¹F ${^{\circ}}{_3}$	56.800	56.8221

^a NIST.

Table 3: Target levels of Cr XIX and Mn XX, and their threshold energies (in Ryd).
Cr XIX Mn XX

Index Configuration Level Expt.^a GRASP Configuration Level Expt.^a GRASP

1...... 1s²2s²2p² ³P₀ 0.0000 0.0000 1s²2s²2p² ³P₀ 0.0000 0.0000

2...... 1s²2s²2p² ³P₁ 0.4357 0.4329 1s²2s²2p² ³P₁ 0.5420 0.5410

3...... 1s²2s²2p² ³P₂ 0.7514 0.7525 1s²2s²2p² ³P₂ 0.8980 0.9020

4...... 1s²2s²2p² ¹D₂ 1.6822 1.7034 1s²2s²2p² ¹D₂ 1.9342 1.9540

5...... 1s²2s²2p² ¹S₀ 2.7220 2.7311 1s²2s²2p² ¹S₀ 3.0352 3.0422

6...... 1s²2s2p³ ⁵S ${^{\circ}}{_2}$ 3.6748 3.6090 1s²2s2p³ ⁵S ${^{\circ}}{_2}$ 4.0374 3.9730

7...... 1s²2s2p³ ³D ${^{\circ}}{_2}$ 6.1203 6.1628 1s²2s2p³ ³D ${^{\circ}}{_2}$ 6.5858 6.6282

8...... 1s²2s2p³ ³D ${^{\circ}}{_1}$ 6.1307 6.1747 1s²2s2p³ ³D ${^{\circ}}{_1}$ 6.5892 6.6358

9...... 1s²2s2p³ ³D ${^{\circ}}{_3}$ 6.2588 6.2985 1s²2s2p³ ³D ${^{\circ}}{_3}$ 6.7701 6.8092

10...... 1s²2s2p³ ³P ${^{\circ}}{_0}$ 7.1913 7.2424 1s²2s2p³ ³P ${^{\circ}}{_0}$ 7.7488 7.8016

11...... 1s²2s2p³ ³P ${^{\circ}}{_1}$ 7.2366 7.2871 1s²2s2p³ ³P ${^{\circ}}{_1}$ 7.8080 7.8617

12...... 1s²2s2p³ ³P ${^{\circ}}{_2}$ 7.3334 7.3826 1s²2s2p³ ³P ${^{\circ}}{_2}$ 7.9333 7.9863

13...... 1s²2s2p³ ³S ${^{\circ}}{_1}$ 8.7470 8.8644 1s²2s2p³ ³S ${^{\circ}}{_1}$ 9.3451 9.4660

14...... 1s²2s2p³ ¹D ${^{\circ}}{_2}$ 8.8959 9.0259 1s²2s2p³ ¹D ${^{\circ}}{_2}$ 9.5581 9.6872

15...... 1s²2s2p³ ¹P ${^{\circ}}{_1}$ 9.9388 10.0787 1s²2s2p³ ¹P ${^{\circ}}{_1}$ 10.685 10.8245

16...... 1s²2p⁴ ³P₂ 13.215 13.3569 1s²2p⁴ ³P₂ 14.086 14.2310

17...... 1s²2p⁴ ³P₁ 13.800 13.9329 1s²2p⁴ ³P₁ 14.796 14.9331

18...... 1s²2p⁴ ³P₀ 13.833 13.9737 1s²2p⁴ ³P₀ 14.798 14.9467

19...... 1s²2p⁴ ¹D₂ 14.455 14.6399 1s²2p⁴ ¹D₂ 15.476 15.6618

20...... 1s²2p⁴ ¹S₀ 16.286 16.5100 1s²2p⁴ ¹S₀ 17.432 17.6580

21...... 1s²2s²2p3s ³P ${^{\circ}}{_0}$ ...... 57.7323 1s²2s²2p3s ³P ${^{\circ}}{_0}$ ...... 63.6071

22...... 1s²2s²2p3s ³P ${^{\circ}}{_1}$ ...... 57.8035 1s²2s²2p3s ³P ${^{\circ}}{_1}$ ...... 63.6839

23...... 1s²2s²2p3s ³P ${^{\circ}}{_2}$ ...... 58.4790 1s²2s²2p3s ³P ${^{\circ}}{_2}$ ...... 64.5025

24...... 1s²2s²2p3s ¹P ${^{\circ}}{_1}$ ...... 58.6867 1s²2s²2p3s ¹P ${^{\circ}}{_1}$ ...... 64.7184

25...... 1s²2s²2p3p ³D₁ ...... 59.2125 1s²2s²2p3p ³D₁ ...... 65.1680

26...... 1s²2s²2p3p ¹P₁ ...... 59.5998 1s²2s²2p3p ¹P₁ ..... 65.6133

27...... 1s²2s²2p3p ³D₂ ...... 59.6202 1s²2s²2p3p ³D₂ ..... 65.6400

28...... 1s²2s²2p3p ³P₀ ...... 59.7770 1s²2s²2p3p ³P₀ ...... 65.7798

29...... 1s²2s²2p3p ³P₁ ...... 60.1408 1s²2s²2p3p ³P₁ ..... 66.2625

30...... 1s²2s²2p3p ³D₃ ...... 60.1932 1s²2s²2p3p ³D₃ ...... 66.3386

31...... 1s²2s²2p3p ³S₁ ...... 60.3047 1s²2s²2p3p ³S₁ ...... 66.4407

32...... 1s²2s²2p3p ³P₂ ...... 60.3497 1s²2s²2p3p ³P₂ ..... 66.4770

33...... 1s²2s²2p3p ¹D₂ ...... 60.8463 1s²2s²2p3p ¹D₂ ...... 67.0120

34...... 1s²2s²2p3d ³F ${^{\circ}}{_2}$ ...... 61.1247 1s²2s²2p3d ³F ${^{\circ}}{_2}$ ...... 67.2078

35...... 1s²2s²2p3p ¹S₀ ...... 61.3854 1s²2s²2p3d ³F ${^{\circ}}{_3}$ ...... 67.5120

36...... 1s²2s²2p3d ³F ${^{\circ}}{_3}$ ...... 61.3904 1s²2s²2p3p ¹S₀ ...... 67.5645

37...... 1s²2s²2p3d ¹D ${^{\circ}}{_2}$ ...... 61.4547 1s²2s²2p3d ¹D ${^{\circ}}{_2}$ ...... 67.5718

38...... 1s²2s²2p3d ³D ${^{\circ}}{_1}$ ...... 61.6191 1s²2s²2p3d ³D ${^{\circ}}{_1}$ ...... 67.7359

39...... 1s²2s²2p3d ³F ${^{\circ}}{_4}$ ...... 61.9066 1s²2s²2p3d ³F ${^{\circ}}{_4}$ ...... 68.1478

40...... 1s²2s²2p3d ³D ${^{\circ}}{_2}$ ...... 61.9896 1s²2s²2p3d ³D ${^{\circ}}{_2}$ ...... 68.2234

41...... 1s²2s²2p3d ³D ${^{\circ}}{_3}$ ...... 62.1706 1s²2s²2p3d ³D ${^{\circ}}{_3}$ ...... 68.4171

42...... 1s²2s²2p3d ³P ${^{\circ}}{_2}$ ...... 62.2760 1s²2s²2p3d ³P ${^{\circ}}{_2}$ ...... 68.5336

43...... 1s²2s²2p3d ³P ${^{\circ}}{_1}$ ...... 62.2865 1s²2s²2p3d ³P ${^{\circ}}{_1}$ ...... 68.5390

44...... 1s²2s²2p3d ³P ${^{\circ}}{_0}$ ...... 62.3028 1s²2s²2p3d ³P ${^{\circ}}{_0}$ ...... 68.5544

45...... 1s²2s²2p3d ¹P ${^{\circ}}{_1}$ ...... 62.7629 1s²2s²2p3d ¹P ${^{\circ}}{_1}$ ...... 69.0318

46...... 1s²2s²2p3d ¹F ${^{\circ}}{_3}$ ...... 62.7836 1s²2s²2p3d ¹F ${^{\circ}}{_3}$ ...... 69.0611

**Table 3:** Target levels of Cr XIX and Mn XX, and their threshold energies (in Ryd).
	Cr XIX	Mn XX
Index	Configuration	Level	Expt.^a	GRASP	Configuration	Level	Expt.^a	GRASP
1......	1s²2s²2p²	³P₀	0.0000	0.0000	1s²2s²2p²	³P₀	0.0000	0.0000
2......	1s²2s²2p²	³P₁	0.4357	0.4329	1s²2s²2p²	³P₁	0.5420	0.5410
3......	1s²2s²2p²	³P₂	0.7514	0.7525	1s²2s²2p²	³P₂	0.8980	0.9020
4......	1s²2s²2p²	¹D₂	1.6822	1.7034	1s²2s²2p²	¹D₂	1.9342	1.9540
5......	1s²2s²2p²	¹S₀	2.7220	2.7311	1s²2s²2p²	¹S₀	3.0352	3.0422
6......	1s²2s2p³	⁵S ${^{\circ}}{_2}$	3.6748	3.6090	1s²2s2p³	⁵S ${^{\circ}}{_2}$	4.0374	3.9730
7......	1s²2s2p³	³D ${^{\circ}}{_2}$	6.1203	6.1628	1s²2s2p³	³D ${^{\circ}}{_2}$	6.5858	6.6282
8......	1s²2s2p³	³D ${^{\circ}}{_1}$	6.1307	6.1747	1s²2s2p³	³D ${^{\circ}}{_1}$	6.5892	6.6358
9......	1s²2s2p³	³D ${^{\circ}}{_3}$	6.2588	6.2985	1s²2s2p³	³D ${^{\circ}}{_3}$	6.7701	6.8092
10......	1s²2s2p³	³P ${^{\circ}}{_0}$	7.1913	7.2424	1s²2s2p³	³P ${^{\circ}}{_0}$	7.7488	7.8016
11......	1s²2s2p³	³P ${^{\circ}}{_1}$	7.2366	7.2871	1s²2s2p³	³P ${^{\circ}}{_1}$	7.8080	7.8617
12......	1s²2s2p³	³P ${^{\circ}}{_2}$	7.3334	7.3826	1s²2s2p³	³P ${^{\circ}}{_2}$	7.9333	7.9863
13......	1s²2s2p³	³S ${^{\circ}}{_1}$	8.7470	8.8644	1s²2s2p³	³S ${^{\circ}}{_1}$	9.3451	9.4660
14......	1s²2s2p³	¹D ${^{\circ}}{_2}$	8.8959	9.0259	1s²2s2p³	¹D ${^{\circ}}{_2}$	9.5581	9.6872
15......	1s²2s2p³	¹P ${^{\circ}}{_1}$	9.9388	10.0787	1s²2s2p³	¹P ${^{\circ}}{_1}$	10.685	10.8245
16......	1s²2p⁴	³P₂	13.215	13.3569	1s²2p⁴	³P₂	14.086	14.2310
17......	1s²2p⁴	³P₁	13.800	13.9329	1s²2p⁴	³P₁	14.796	14.9331
18......	1s²2p⁴	³P₀	13.833	13.9737	1s²2p⁴	³P₀	14.798	14.9467
19......	1s²2p⁴	¹D₂	14.455	14.6399	1s²2p⁴	¹D₂	15.476	15.6618
20......	1s²2p⁴	¹S₀	16.286	16.5100	1s²2p⁴	¹S₀	17.432	17.6580
21......	1s²2s²2p3s	³P ${^{\circ}}{_0}$	......	57.7323	1s²2s²2p3s	³P ${^{\circ}}{_0}$	......	63.6071
22......	1s²2s²2p3s	³P ${^{\circ}}{_1}$	......	57.8035	1s²2s²2p3s	³P ${^{\circ}}{_1}$	......	63.6839
23......	1s²2s²2p3s	³P ${^{\circ}}{_2}$	......	58.4790	1s²2s²2p3s	³P ${^{\circ}}{_2}$	......	64.5025
24......	1s²2s²2p3s	¹P ${^{\circ}}{_1}$	......	58.6867	1s²2s²2p3s	¹P ${^{\circ}}{_1}$	......	64.7184
25......	1s²2s²2p3p	³D₁	......	59.2125	1s²2s²2p3p	³D₁	......	65.1680
26......	1s²2s²2p3p	¹P₁	......	59.5998	1s²2s²2p3p	¹P₁	.....	65.6133
27......	1s²2s²2p3p	³D₂	......	59.6202	1s²2s²2p3p	³D₂	.....	65.6400
28......	1s²2s²2p3p	³P₀	......	59.7770	1s²2s²2p3p	³P₀	......	65.7798
29......	1s²2s²2p3p	³P₁	......	60.1408	1s²2s²2p3p	³P₁	.....	66.2625
30......	1s²2s²2p3p	³D₃	......	60.1932	1s²2s²2p3p	³D₃	......	66.3386
31......	1s²2s²2p3p	³S₁	......	60.3047	1s²2s²2p3p	³S₁	......	66.4407
32......	1s²2s²2p3p	³P₂	......	60.3497	1s²2s²2p3p	³P₂	.....	66.4770
33......	1s²2s²2p3p	¹D₂	......	60.8463	1s²2s²2p3p	¹D₂	......	67.0120
34......	1s²2s²2p3d	³F ${^{\circ}}{_2}$	......	61.1247	1s²2s²2p3d	³F ${^{\circ}}{_2}$	......	67.2078
35......	1s²2s²2p3p	¹S₀	......	61.3854	1s²2s²2p3d	³F ${^{\circ}}{_3}$	......	67.5120
36......	1s²2s²2p3d	³F ${^{\circ}}{_3}$	......	61.3904	1s²2s²2p3p	¹S₀	......	67.5645
37......	1s²2s²2p3d	¹D ${^{\circ}}{_2}$	......	61.4547	1s²2s²2p3d	¹D ${^{\circ}}{_2}$	......	67.5718
38......	1s²2s²2p3d	³D ${^{\circ}}{_1}$	......	61.6191	1s²2s²2p3d	³D ${^{\circ}}{_1}$	......	67.7359
39......	1s²2s²2p3d	³F ${^{\circ}}{_4}$	......	61.9066	1s²2s²2p3d	³F ${^{\circ}}{_4}$	......	68.1478
40......	1s²2s²2p3d	³D ${^{\circ}}{_2}$	......	61.9896	1s²2s²2p3d	³D ${^{\circ}}{_2}$	......	68.2234
41......	1s²2s²2p3d	³D ${^{\circ}}{_3}$	......	62.1706	1s²2s²2p3d	³D ${^{\circ}}{_3}$	......	68.4171
42......	1s²2s²2p3d	³P ${^{\circ}}{_2}$	......	62.2760	1s²2s²2p3d	³P ${^{\circ}}{_2}$	......	68.5336
43......	1s²2s²2p3d	³P ${^{\circ}}{_1}$	......	62.2865	1s²2s²2p3d	³P ${^{\circ}}{_1}$	......	68.5390
44......	1s²2s²2p3d	³P ${^{\circ}}{_0}$	......	62.3028	1s²2s²2p3d	³P ${^{\circ}}{_0}$	......	68.5544
45......	1s²2s²2p3d	¹P ${^{\circ}}{_1}$	......	62.7629	1s²2s²2p3d	¹P ${^{\circ}}{_1}$	......	69.0318
46......	1s²2s²2p3d	¹F ${^{\circ}}{_3}$	......	62.7836	1s²2s²2p3d	¹F ${^{\circ}}{_3}$	......	69.0611

^a NIST.

In Tables 1-3 we list the energy levels arising from the (1s²) 2s²2p², 2s2p³, 2p⁴, 2s²2p3s, 2s²2p3p and 2s²2p3d configurations of C-like ions, and compare our threshold energies for K XIV, Sc XVI, Ti XVII, V XVIII, Cr XIX and Mn XX with the experimental values compiled by NIST (National Institute for Standards and Technology: www.physics.nist.gov/PhysRefData). Since the ordering of the energy levels is not the same for all C-like ions, the levels are listed in Tables 1-3 for each ion. The first column of each table provides an index for the corresponding level. However, it may be noted that the experimental values are not available for all levels, and the accuracy for some of these, especially those among the 2s²2p3s, 2s²2p3p and 2s²2p3d configurations, is not very high. The theoretical values available in the literature are mostly confined to the lowest 20 levels, but corresponding results involving some of the higher excited levels have been reported by Fawcett (1987) and Zhang & Sampson (1997) in the form of transition wavelengths.

The agreement of our level energies with the experimental ones is excellent (within 3%) for all levels and for all ions. It may be noted that the energy order of the theoretical and experimental energy levels is slightly different in a few instances; see, for example, the highest two levels of K XIV and Sc XVI. However, the energy differences for such levels are very small ( $\le$ 0.03 Ryd). This problem of energy order is frequently encountered in all theoretical work, especially when the energy separation of the levels is very small. Furthermore, in the absence of definitive experimental level energies in most of the cases, a correct energy order cannot be confirmed. In any event, it does not affect the computed values of the oscillator strengths and collision strengths.

In Tables 4-9 we present our oscillator strengths and radiative rates (in length form only) for allowed transitions in K XIV, Sc XVI, Ti XVII, V XVIII, Cr XIX and Mn XX. The indices used to represent the levels of a transition are already given in Tables 1-3. Since the indices of the various levels are not the same for all the ions, we have included in these tables the shorter forms of the lower and upper levels of a transition. This should facilitate their identification.

The other values available in the literature for oscillator strengths (f-values) and radiative rates (A-values), apart from those of Fawcett (1987), are of Zhang & Sampson (1996) for a few transitions among the lowest 20 levels. Their results are not only the most recent for the present ions, but are also similar and comparable to our present calculations, as they too have adopted the GRASP code, but have restricted the inclusion of CI among the first three configurations only, i.e. 2s²2p², 2s2p³ and 2p⁴. Zhang & Sampson (1997) have performed a larger calculation including the levels of the 2s²2p3s, 2s²2p3p and 2s²2p3d configurations, but have not reported any data for the ions under discussion here. However, a comparison between our present and their earlier results for oscillator strengths shows agreement within 20% for the available common transitions for all ions. This is an expected result considering the limited amount of CI included by them.

Among the higher excited levels, the only results available in the literature are by Fawcett (1987), who has adopted the Hartree-Fock relativistic (HFR) code of Cowan (1981). In Table 10 we compare our values of oscillator strengths for a few representative transitions with his HFR results. The indices used to represent a transition correspond to those of K XIV, but a shorter form of the transitions has been included in Col. 3 in order to facilitate an easy identification of the same transition in different ions. Generally, our GRASP and earlier HFR f-values agree within 10%, but for a few transitions (such as 2-40 and 5-45) the differences are up to 30%, and for the 2-45 (2s²2p² ³P₁-2s²2p3d ¹P ${^{\circ}}{_1}$ ) and 4-37 (2s²2p² ¹D₂-2s²2p3d ¹D ${^{\circ}}{_2}$ ) transitions, the two sets of results differ by a factor of two. However, the transitions for which differences between the two sets of calculations are significant are weaker transitions, whose f-values are comparatively small. These differences arise due to different amount of CI included in the calculations.

Table 10: Comparison between our present GRASP (first rows) oscillator strengths with the HFR (second rows) results of Fawcett (1987) for a few transitions of C-like ions. ( $a \pm b \equiv a\times 10^{{\pm }b}$ ).
i j Transition K XIV Sc XVI Ti XVII V XVIII Cr XIX Mn XX

1 22 ³P₀-³P ${^{\circ}}{_1}$ 5.995-2 5.813-2 5.748-2 5.697-2 5.655-2 5.619-2

6.600-2 6.400-2 6.400-2 6.300-2 6.300-2 6.300-2

1 24 ³P₀-¹P ${^{\circ}}{_1}$ 2.042-3 2.044-3 1.941-3 1.789-3 1.605-3 1.404-3

2.000-3 2.000-3 2.000-3 2.000-3 2.000-3 2.000-2

1 39 ³P₀-³D ${^{\circ}}{_1}$ 1.235-0 1.262-0 1.274-0 1.285-0 1.295-0 1.305-0

1.320-0 1.340-0 1.349-0 1.359-0 1.368-0 1.377-0

2 37 ³P₁-¹D ${^{\circ}}{_2}$ 1.507-1 2.593-1 3.113-1 3.567-1 3.944-1 4.250-1

1.600-1 2.720-1 3.253-1 3.713-1 3.790-1 3.487-1

2 39 ³P₁-³D ${^{\circ}}{_1}$ 1.039-1 9.406-2 9.002-2 8.645-2 8.327-2 8.045-2

1.077-1 9.500-2 9.100-2 8.730-2 8.430-2 8.130-2

2 40 ³P₁-³D ${^{\circ}}{_2}$ 6.162-1 5.015-1 4.480-1 4.019-1 3.643-1 3.347-1

6.400-1 5.200-1 4.647-1 4.177-1 4.090-1 4.397-1

2 42 ³P₁-³P ${^{\circ}}{_2}$ 6.010-2 7.564-2 8.093-2 8.484-2 8.756-2 8.927-2

7.700-2 8.970-2 9.400-2 9.700-2 9.900-2 1.000-1

2 43 ³P₁-³P ${^{\circ}}{_1}$ 2.081-1 2.226-1 2.290-1 2.352-1 2.414-1 2.482-1

2.280-1 2.400-1 2.457-1 2.510-1 2.563-1 2.617-1

2 44 ³P₁-³P ${^{\circ}}{_0}$ 1.035-1 1.051-1 1.059-1 1.066-1 1.072-1 1.072-1

1.100-1 1.110-1 1.120-1 1.130-1 1.133-1 1.140-1

2 45 ³P₁-¹P ${^{\circ}}{_1}$ 5.607-3 7.545-4 6.570-3 1.004-2 1.421-2 2.039-2

7.700-3 6.700-3 9.000-3 8.000-3 8.700-3 1.070-2

3 22 ³P₂-³P ${^{\circ}}{_1}$ 1.695-2 1.760-2 1.808-2 1.863-2 1.921-2 1.979-2

1.840-2 1.960-2 1.960-2 2.020-2 2.080-2 2.140-2

3 23 ³P₂-³P ${^{\circ}}{_2}$ 4.530-2 4.247-2 4.088-2 3.918-2 3.737-2 3.550-2

4.940-2 4.600-2 4.420-2 4.220-2 4.020-2 3.820-2

3 35 ³P₂-³F ${^{\circ}}{_2}$ 1.136-2 1.751-2 2.107-2 2.482-2 2.866-2 3.244-2

1.060-2 1.700-2 2.080-2 2.480-2 2.880-2 3.260-2

3 36 ³P₂-³F ${^{\circ}}{_3}$ 5.376-2 8.743-2 1.078-1 1.300-1 1.536-1 1.781-1

5.120-2 8.540-2 1.062-1 1.292-1 1.536-1 1.788-1

3 37 ³P₂-¹D ${^{\circ}}{_2}$ 1.190-2 1.988-2 2.387-2 2.757-2 3.086-2 3.367-2

1.720-2 2.600-2 3.020-2 3.400-2 2.300-2 3.120-2

3 41 ³P₂-³D ${^{\circ}}{_3}$ 7.378-1 7.170-1 7.020-1 6.845-1 6.650-1 6.443-1

7.902-1 7.642-1 7.466-1 7.264-1 7.040-1 6.808-1

3 42 ³P₂-³P ${^{\circ}}{_2}$ 3.398-1 3.213-1 3.082-1 2.927-1 2.753-1 2.565-1

3.564-1 3.328-1 3.174-1 2.998-1 2.804-1 2.600-1

3 43 ³P₂-³P ${^{\circ}}{_1}$ 8.213-2 7.940-2 7.726-2 7.453-2 7.114-2 6.678-2

8.580-2 8.440-2 7.980-2 7.680-2 7.370-2 6.920-2

3 46 ³P₂-¹F ${^{\circ}}{_3}$ 4.921-3 1.299-2 1.943-2 2.760-2 3.730-2 4.809-2

6.400-3 1.600-2 2.360-2 3.320-2 4.420-2 5.640-2

4 24 ¹D₂-¹P ${^{\circ}}{_1}$ 4.696-2 4.428-2 4.305-2 4.185-2 4.066-2 3.947-2

5.440-2 5.040-2 4.860-2 4.700-2 4.520-2 4.360-2

4 35 ¹D₂-³F ${^{\circ}}{_2}$ 3.957-2 3.449-2 3.153-2 2.839-2 2.517-2 2.198-2

5.280-2 3.060-2 2.860-2 2.600-2 2.320-2 2.040-2

4 37 ¹D₂-¹D ${^{\circ}}{_2}$ 1.170-1 8.670-2 7.182-2 5.856-2 4.729-2 3.798-2

1.356-1 9.600-2 7.840-2 6.300-2 5.020-2 7.540-2

4 42 ¹D₂-³P ${^{\circ}}{_2}$ 2.728-2 4.809-2 6.188-2 7.782-2 9.554-2 1.145-1

3.120-2 5.480-2 7.020-2 8.740-2 1.064-1 1.262-1

4 45 ¹D₂-¹P ${^{\circ}}{_1}$ 1.263-2 9.475-3 1.235-2 1.292-2 1.332-2 1.330-2

7.400-3 8.200-3 8.600-3 7.400-3 8.800-3 9.400-3

**Table 10:** Comparison between our present GRASP (first rows) oscillator strengths with the HFR (second rows) results of Fawcett (1987) for a few transitions of C-like ions. ( $a \pm b \equiv a\times 10^{{\pm }b}$ ).
i	j	Transition	K XIV	Sc XVI	Ti XVII	V XVIII	Cr XIX	Mn XX
1	22	³P₀-³P ${^{\circ}}{_1}$	5.995-2	5.813-2	5.748-2	5.697-2	5.655-2	5.619-2
			6.600-2	6.400-2	6.400-2	6.300-2	6.300-2	6.300-2
1	24	³P₀-¹P ${^{\circ}}{_1}$	2.042-3	2.044-3	1.941-3	1.789-3	1.605-3	1.404-3
			2.000-3	2.000-3	2.000-3	2.000-3	2.000-3	2.000-2
1	39	³P₀-³D ${^{\circ}}{_1}$	1.235-0	1.262-0	1.274-0	1.285-0	1.295-0	1.305-0
			1.320-0	1.340-0	1.349-0	1.359-0	1.368-0	1.377-0
2	37	³P₁-¹D ${^{\circ}}{_2}$	1.507-1	2.593-1	3.113-1	3.567-1	3.944-1	4.250-1
			1.600-1	2.720-1	3.253-1	3.713-1	3.790-1	3.487-1
2	39	³P₁-³D ${^{\circ}}{_1}$	1.039-1	9.406-2	9.002-2	8.645-2	8.327-2	8.045-2
			1.077-1	9.500-2	9.100-2	8.730-2	8.430-2	8.130-2
2	40	³P₁-³D ${^{\circ}}{_2}$	6.162-1	5.015-1	4.480-1	4.019-1	3.643-1	3.347-1
			6.400-1	5.200-1	4.647-1	4.177-1	4.090-1	4.397-1
2	42	³P₁-³P ${^{\circ}}{_2}$	6.010-2	7.564-2	8.093-2	8.484-2	8.756-2	8.927-2
			7.700-2	8.970-2	9.400-2	9.700-2	9.900-2	1.000-1
2	43	³P₁-³P ${^{\circ}}{_1}$	2.081-1	2.226-1	2.290-1	2.352-1	2.414-1	2.482-1
			2.280-1	2.400-1	2.457-1	2.510-1	2.563-1	2.617-1
2	44	³P₁-³P ${^{\circ}}{_0}$	1.035-1	1.051-1	1.059-1	1.066-1	1.072-1	1.072-1
			1.100-1	1.110-1	1.120-1	1.130-1	1.133-1	1.140-1
2	45	³P₁-¹P ${^{\circ}}{_1}$	5.607-3	7.545-4	6.570-3	1.004-2	1.421-2	2.039-2
			7.700-3	6.700-3	9.000-3	8.000-3	8.700-3	1.070-2
3	22	³P₂-³P ${^{\circ}}{_1}$	1.695-2	1.760-2	1.808-2	1.863-2	1.921-2	1.979-2
			1.840-2	1.960-2	1.960-2	2.020-2	2.080-2	2.140-2
3	23	³P₂-³P ${^{\circ}}{_2}$	4.530-2	4.247-2	4.088-2	3.918-2	3.737-2	3.550-2
			4.940-2	4.600-2	4.420-2	4.220-2	4.020-2	3.820-2
3	35	³P₂-³F ${^{\circ}}{_2}$	1.136-2	1.751-2	2.107-2	2.482-2	2.866-2	3.244-2
			1.060-2	1.700-2	2.080-2	2.480-2	2.880-2	3.260-2
3	36	³P₂-³F ${^{\circ}}{_3}$	5.376-2	8.743-2	1.078-1	1.300-1	1.536-1	1.781-1
			5.120-2	8.540-2	1.062-1	1.292-1	1.536-1	1.788-1
3	37	³P₂-¹D ${^{\circ}}{_2}$	1.190-2	1.988-2	2.387-2	2.757-2	3.086-2	3.367-2
			1.720-2	2.600-2	3.020-2	3.400-2	2.300-2	3.120-2
3	41	³P₂-³D ${^{\circ}}{_3}$	7.378-1	7.170-1	7.020-1	6.845-1	6.650-1	6.443-1
			7.902-1	7.642-1	7.466-1	7.264-1	7.040-1	6.808-1
3	42	³P₂-³P ${^{\circ}}{_2}$	3.398-1	3.213-1	3.082-1	2.927-1	2.753-1	2.565-1
			3.564-1	3.328-1	3.174-1	2.998-1	2.804-1	2.600-1
3	43	³P₂-³P ${^{\circ}}{_1}$	8.213-2	7.940-2	7.726-2	7.453-2	7.114-2	6.678-2
			8.580-2	8.440-2	7.980-2	7.680-2	7.370-2	6.920-2
3	46	³P₂-¹F ${^{\circ}}{_3}$	4.921-3	1.299-2	1.943-2	2.760-2	3.730-2	4.809-2
			6.400-3	1.600-2	2.360-2	3.320-2	4.420-2	5.640-2
4	24	¹D₂-¹P ${^{\circ}}{_1}$	4.696-2	4.428-2	4.305-2	4.185-2	4.066-2	3.947-2
			5.440-2	5.040-2	4.860-2	4.700-2	4.520-2	4.360-2
4	35	¹D₂-³F ${^{\circ}}{_2}$	3.957-2	3.449-2	3.153-2	2.839-2	2.517-2	2.198-2
			5.280-2	3.060-2	2.860-2	2.600-2	2.320-2	2.040-2
4	37	¹D₂-¹D ${^{\circ}}{_2}$	1.170-1	8.670-2	7.182-2	5.856-2	4.729-2	3.798-2
			1.356-1	9.600-2	7.840-2	6.300-2	5.020-2	7.540-2
4	42	¹D₂-³P ${^{\circ}}{_2}$	2.728-2	4.809-2	6.188-2	7.782-2	9.554-2	1.145-1
			3.120-2	5.480-2	7.020-2	8.740-2	1.064-1	1.262-1
4	45	¹D₂-¹P ${^{\circ}}{_1}$	1.263-2	9.475-3	1.235-2	1.292-2	1.332-2	1.330-2
			7.400-3	8.200-3	8.600-3	7.400-3	8.800-3	9.400-3

Table 10: continued.
i j Transition K XIV Sc XVI Ti XVII V XVIII Cr XIX Mn XX

4 46 ¹D₂-¹F ${^{\circ}}{_3}$ 1.032-0 1.033-0 1.028-0 1.020-0 1.009-0 9.956-1

1.072-0 1.068-0 1.060-0 1.050-0 1.036-0 1.020-0

5 22 ¹S₀-³P ${^{\circ}}{_1}$ 3.358-3 3.595-3 3.560-3 3.443-3 3.263-3 3.041-3

4.000-3 4.000-3 4.000-3 4.000-3 4.000-3 4.000-3

5 24 ¹S₀-¹P ${^{\circ}}{_1}$ 7.402-2 7.097-2 6.978-2 6.876-2 6.788-2 6.712-2

7.800-2 7.500-2 7.300-2 7.200-2 7.100-2 7.000-2

5 39 ¹S₀-³D ${^{\circ}}{_1}$ 1.092-2 1.320-2 1.384-2 1.410-2 1.402-2 1.362-2

1.300-2 1.500-2 1.500-2 1.500-2 1.500-2 1.500-2

5 43 ¹S₀-³P ${^{\circ}}{_1}$ 2.246-3 3.195-3 3.803-3 4.507-3 5.294-3 6.115-3

2.000-3 3.000-3 3.000-3 4.000-3 4.000-3 5.000-3

5 45 ¹S₀-¹P ${^{\circ}}{_1}$ 1.337-0 1.174-0 1.314-0 1.281-0 1.198-0 1.004-0

1.394-0 1.387-0 1.368-0 1.334-0 1.365-0 1.344-0

**Table 10:** continued.
i	j	Transition	K XIV	Sc XVI	Ti XVII	V XVIII	Cr XIX	Mn XX
4	46	¹D₂-¹F ${^{\circ}}{_3}$	1.032-0	1.033-0	1.028-0	1.020-0	1.009-0	9.956-1
			1.072-0	1.068-0	1.060-0	1.050-0	1.036-0	1.020-0
5	22	¹S₀-³P ${^{\circ}}{_1}$	3.358-3	3.595-3	3.560-3	3.443-3	3.263-3	3.041-3
			4.000-3	4.000-3	4.000-3	4.000-3	4.000-3	4.000-3
5	24	¹S₀-¹P ${^{\circ}}{_1}$	7.402-2	7.097-2	6.978-2	6.876-2	6.788-2	6.712-2
			7.800-2	7.500-2	7.300-2	7.200-2	7.100-2	7.000-2
5	39	¹S₀-³D ${^{\circ}}{_1}$	1.092-2	1.320-2	1.384-2	1.410-2	1.402-2	1.362-2
			1.300-2	1.500-2	1.500-2	1.500-2	1.500-2	1.500-2
5	43	¹S₀-³P ${^{\circ}}{_1}$	2.246-3	3.195-3	3.803-3	4.507-3	5.294-3	6.115-3
			2.000-3	3.000-3	3.000-3	4.000-3	4.000-3	5.000-3
5	45	¹S₀-¹P ${^{\circ}}{_1}$	1.337-0	1.174-0	1.314-0	1.281-0	1.198-0	1.004-0
			1.394-0	1.387-0	1.368-0	1.334-0	1.365-0	1.344-0

In general, inclusion of larger CI improves the wavefunctions, and hence leads to a more accurate determination of energy levels and radiative rates for a majority of transitions. However, occasionally it may also result in comparatively reduced accuracy for a few transitions, as has specifically been discussed by Aggarwal (1998) for transitions in Fe XXI. A further example of this is provided by the 2-45 (2s²2p² ³P₁-2s²2p3d ¹P ${^{\circ}}{_1}$ ) transition in Sc XVI, whose f-value of $7.545\times 10^{-4}$ is incongrous with the corresponding f-values of other ions as shown in Table 10. Our calculations with 6, 12, 15, 16, 19 and 20 configurations yield the f-values $3.807\times10^{-3}$ , $1.535\times10^{-4}$ , $7.545\times 10^{-4}$ , $5.168\times10^{-3}$ , $5.184\times10^{-3}$ and $5.130\times10^{-3}$ , respectively. Clearly, the f-value for this transition should be $\sim$ 10^-3, and the presently reported result of $7.545\times 10^{-4}$ is underestimated by a factor of seven. There could be some other similar examples, but a majority of transitions are unaffected by such inconsistencies.

The accuracy of the calculated f- or A-values is generally (but not conclusively) determined by the agreement between their length and velocity forms. In any large calculation involving a large number of transitions, as in the present work, the agreement between the two forms for all the transitions is never satisfactory. Weak transitions (f < 0.10) being sensitive to mixing often show large variations, which can be over an order of magnitude. However, these transitions are not very important, in general. For transitions whose f-values are significantly larger ( $\ge$ 0.10), the agreement between the two forms is within 20%, and the only exception is the 33-46 (2p3p ¹D₂-2p3d ¹F ${^{\circ}}{_3}$ ) transition in K XIV, for which the length form is higher by a factor of two. For transitions with f-values $\ge$ 0.01, the two forms agree within a factor of two for all transitions in all ions. In fact, for a majority of weak transitions the two forms agree to better than 40%. This is highly satisfactory.

The measurements of A-values, in the form of lifetimes, can provide a good check on the theoretical results, and hence can help to improve the accuracy. However, to the best of our knowledge there are no experimental values available in the literature for the ions considered here. Some experiments have reported the lifetimes for the 2s²2p² ¹S₀, ¹D₂ and 2s2p³ ⁵S ${^{\circ}}{_2}$ levels in other C-like ions, (see, for example, Trabert 2002 and references therein). We hope experiments in the future will be performed for other C-like ions also, which will help us in improving upon the accuracy of the calculated atomic data.

3 Results and discussion