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Release 17bSeptember 2015
NIST Standard Reference Database 101
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III.G.1.a.

Comparison of levels of theory for N-N


Click on an entry for a histogram of the values.
The subscript refers to how many bonds of that type have been calculated.
average calculated bond lengths (Å)
Methods with predefined basis sets
semi-empirical AM1 1.2153
25
PM3 1.4048
29
PM6 1.2867
53
composite G2 1.2553
48
G3 1.2606
51
G3B3 1.2993
54
G3MP2 1.1721
3
G4 1.2869
54
CBS-Q 1.2294
37

average calculated bond lengths (Å)
Methods with standard basis sets
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) 6-311+G(3df,2pd) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z aug-cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ Sadlej_pVTZ
hartree fock HF 1.3350
54
1.2912
51
1.2913
51
1.2762
51
1.2638
54
1.2603
51
1.2072
25
1.2576
51
1.2600
54
1.2596
54
1.2876
32
1.0665
1
1.2585
54
1.2602
51
1.2457
49
1.1927
21
1.2611
51
1.2491
49
1.1955
19
1.0762
1
1.0760
1
1.1380
6
1.1296
6
1.0846
2
ROHF 1.2150
4
1.1616
6
1.1631
8
1.1714
7
1.1543
9
1.1521
8
1.1515
8
1.1468
8
1.1545
6
1.1381
4
1.1576
1
  1.1846
3
1.1514
8
1.1434
8
1.1542
4
1.1596
6
1.1506
6
1.1539
4
         
density functional LSDA 1.3906
54
1.3287
54
1.3286
54
1.3127
54
1.2936
54
1.2935
54
1.2920
54
1.2886
54
1.2887
54
1.2896
54
1.0944
1
1.0944
1
1.2313
16
1.2926
54
1.2855
54
1.1464
3
1.2926
53
1.2161
17
1.1440
3
1.1319
1
1.1319
1
     
SVWN 1.1890
1
1.3219
52
1.1181
1
1.1229
1
1.3007
50
1.2413
16
1.2932
52
1.2340
16
1.2341
16
1.2367
16
1.0944
1
1.0944
1
1.3243
46
1.2400
16
1.2311
16
1.0939
1
1.2377
15
1.2286
15
1.0937
1
1.1319
1
1.1319
1
     
BLYP 1.4345
54
1.3627
54
1.3218
37
1.3413
51
1.3123
55
1.3210
51
1.3196
51
1.2825
37
1.3187
54
1.3190
54
1.1031
1
1.1031
1
1.2513
16
1.3229
50
1.3127
51
1.1022
1
1.3487
30
1.2458
6
1.1021
1
1.1400
1
1.1400
1
     
B1B95 1.3983
54
1.3254
54
1.3253
54
1.3096
54
1.2888
54
1.2902
54
1.2892
54
1.2868
54
1.2868
54
1.2867
54
1.1084
2
1.0878
1
1.2259
16
1.2894
54
1.2821
54
1.1457
4
1.2883
53
1.2444
29
1.1360
4
1.1165
1
1.1164
1
     
B3LYP 1.3938
53
1.3332
50
1.3298
51
1.3163
51
1.3019
53
1.2997
54
1.2964
51
1.2937
51
1.2469
30
1.2937
51
1.3274
27
1.0912
1
1.2901
54
1.2988
54
1.2831
48
1.2231
19
1.2539
32
1.2917
52
1.2209
19
1.1217
1
1.1217
1
1.1722
5
1.1618
5
1.1218
2
B3LYPultrafine 1.1807
1
1.2945
10
1.1127
1
1.1184
1
1.3042
52
1.2596
10
1.3434
15
1.2533
10
1.0954
1
1.0988
1
1.0912
1
1.0912
1
1.2406
12
1.2412
16
1.2680
26
1.0902
1
1.2395
15
1.2847
53
1.0901
1
         
B3PW91 1.3454
31
1.3260
51
1.3260
51
1.3109
51
1.2881
49
1.2918
51
1.2604
37
1.2881
51
1.2430
30
1.2906
54
1.0910
1
1.0910
1
1.2301
16
1.2913
51
1.2850
51
1.0901
1
1.3191
30
1.2245
6
1.0901
1
1.1215
1
1.1214
1
     
mPW1PW91 1.3352
31
1.3209
51
1.2724
31
1.3090
54
1.2847
48
1.3320
51
1.2862
51
1.2837
51
1.2860
54
1.2861
54
1.0888
1
1.0888
1
1.2263
15
1.2867
51
1.2409
34
1.0880
1
1.2938
41
1.2161
16
1.0879
1
1.1178
1
1.1178
1
     
M06-2X 1.3071
16
1.2624
16
1.2757
42
1.2485
16
1.2867
53
1.2321
16
1.2309
16
1.2276
16
1.2278
16
1.2380
18
1.0862
1
1.0862
1
1.2238
15
1.2315
16
1.2349
18
1.0854
1
1.2305
15
1.2341
17
1.0853
1
1.1105
1
1.1102
1
     
PBEPBE 1.3618
31
1.3533
54
1.3053
29
1.2894
29
1.3129
54
1.3126
54
1.3111
54
1.3083
54
1.3087
54
1.3053
52
1.3262
30
1.1031
1
1.2431
15
1.3141
52
1.3057
54
1.1660
4
1.2503
15
1.2359
22
1.1579
4
1.1395
1
1.1396
1
    1.1319
2
PBEPBEultrafine 1.1954
1
1.3112
10
1.1273
1
1.1303
1
1.3236
46
1.2704
10
1.2682
10
1.2654
10
1.1072
1
1.1109
1
1.1031
1
1.1031
1
1.2530
12
1.2527
16
1.2440
16
1.1024
1
1.2506
15
1.2414
15
1.1022
1
         
PBE1PBE 1.3151
16
1.2644
16
1.2644
16
1.2523
16
1.2892
54
1.2353
16
1.2338
16
1.2300
16
1.2301
16
1.2317
16
1.0898
1
1.0898
1
1.2264
15
1.2341
16
1.2272
16
1.0889
1
1.2328
15
1.2254
15
1.0889
1
1.1188
1
1.1188
1
     
HSEh1PBE 1.3157
16
1.3205
53
1.2681
16
1.2541
16
1.2908
52
1.2353
16
1.2896
53
1.2301
16
1.2302
16
1.2315
16
1.0894
1
1.0894
1
1.2264
15
1.2342
16
1.2852
53
1.0885
1
1.2329
15
1.2251
15
1.0885
1
1.1187
1
1.1187
1
     
TPSSh   1.2977
14
1.2977
14
1.2816
14
1.2980
54
1.2634
14
1.2976
54
1.2576
14
  1.2916
49
    1.2578
11
1.2625
14
1.2923
54
  1.2617
13
1.2541
13
           
wB97X-D 1.2942
1
1.2198
1
1.3182
56
1.2135
1
1.2932
56
1.2019
1
1.1942
1
1.1939
1
1.2898
56
1.1953
1
    1.1867
1
1.2018
1
1.2874
56
1.1850
1
1.1939
1
1.2878
55
1.1811
1
         
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) 6-311+G(3df,2pd) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z aug-cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ Sadlej_pVTZ
Moller Plesset perturbation MP2 1.3618
30
1.3652
51
1.3656
51
1.3481
51
1.3299
55
1.3095
51
1.3104
54
1.3255
54
1.3031
51
1.2981
50
1.1131
1
1.1131
1
1.2993
54
1.3114
54
1.2787
41
1.2034
12
1.2703
32
1.2542
24
1.2015
12
1.1588
1
1.1600
1
1.1826
7
1.1690
7
1.1484
2
MP2=FULL 1.3586
30
1.3209
34
1.3176
31
1.3029
31
1.3052
52
1.2764
36
1.2772
37
1.3012
51
1.2566
30
1.2575
32
1.1111
1
1.1111
1
1.2467
16
1.2709
34
1.2520
32
1.2005
12
1.2534
26
1.2254
22
1.1983
12
1.1545
1
1.1547
1
1.1818
7
1.1669
7
1.1476
2
ROMP2 1.3056
6
1.2321
6
1.2321
6
1.2273
6
1.2066
6
1.2062
6
1.2054
6
1.2000
6
1.2001
6
1.2081
5
    1.2146
3
1.2070
6
1.1950
6
1.1813
1
1.2082
6
1.1641
2
1.1786
1
         
MP3 1.1757
1
1.1088
1
1.1088
1
1.1149
1
1.2897
51
1.1057
1
1.2909
54
1.0949
1
1.0949
1
1.0961
1
1.0895
1
1.0895
1
1.2370
12
1.2465
12
1.2351
12
1.0865
1
1.1067
1
1.0899
1
1.0867
1
  1.1109
1
     
MP3=FULL   1.1683
1
1.1683
1
1.1687
1
1.2897
54
1.1721
1
1.2892
53
1.1664
1
1.1664
1
1.1657
1
    1.2491
11
1.2587
11
1.2434
11
  1.1684
1
1.1558
1
           
MP4 1.2530
3
1.2807
27
1.1403
1
1.1470
1
1.2789
32
1.1282
1
1.1285
1
1.2795
2
1.2723
28
1.3190
6
1.1131
1
1.1131
1
1.2532
15
1.2602
15
1.2727
22
1.1102
1
1.2619
15
1.2270
12
1.1104
1
1.1571
1
1.1580
1
     
MP4=FULL 1.1903
1
1.3096
15
1.1402
1
1.1469
1
1.2595
15
1.1275
1
1.1278
1
1.1182
1
1.2544
15
1.1155
1
1.1112
1
1.1112
1
1.1144
1
1.2594
15
1.2458
15
1.1079
1
1.2609
15
1.2112
11
1.1080
1
1.1527
1
1.1525
1
     
B2PLYP 1.3321
14
1.2906
14
1.2906
14
1.2763
14
1.3077
50
1.2531
14
1.2623
13
1.2465
14
1.2477
14
1.2559
16
1.0992
1
1.0992
1
1.2446
14
1.2523
14
1.2982
51
1.0978
1
1.2515
13
1.2522
15
1.0978
1
         
B2PLYP=FULL 1.3427
13
1.2985
13
1.3033
13
1.2875
13
1.2623
13
1.2635
13
1.2607
13
1.2571
13
1.2583
13
1.2571
13
    1.2542
13
1.2628
13
1.2524
13
  1.2627
12
1.2523
12
           
B2PLYP=FULLultrafine 1.3828
2
1.3114
2
1.3114
2
1.2889
2
1.3322
28
1.2740
2
1.2671
2
1.2686
2
1.2688
2
1.2690
2
    1.2631
2
1.2760
2
1.2619
2
  1.2673
2
1.2569
2
           
Configuration interaction CID 1.2613
4
1.2646
30
1.2519
28
1.2413
28
1.2518
35
1.1040
1
1.1036
1
1.2219
29
1.1713
4
1.2386
6
1.0870
1
1.0870
1
1.0894
1
1.1033
1
1.0873
1
1.0838
1
1.1045
1
1.0873
1
1.0840
1
1.1024
1
1.1023
1
     
CISD 1.2621
4
1.2719
29
1.2537
28
1.2454
28
1.2485
34
  1.1053
1
1.2171
28
1.1730
4
1.2403
6
1.0886
1
1.0886
1
1.0912
1
1.1050
1
1.0890
1
1.0854
1
1.1060
1
1.0889
1
1.0855
1
1.1037
1
1.1035
1
     
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) 6-311+G(3df,2pd) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z aug-cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ Sadlej_pVTZ
Quadratic configuration interaction QCISD 1.3379
7
1.3248
38
1.2779
26
1.2807
28
1.2628
35
1.2677
30
1.2615
31
1.2527
31
1.2578
29
1.2437
25
1.0975
1
1.0975
1
1.2383
14
1.2623
29
1.2404
24
1.0942
1
1.2399
16
1.2158
14
1.0943
1
1.1195
1
1.1195
1
     
QCISD(T) 1.1900
1
1.1278
1
1.1278
1
1.1339
1
1.2688
28
1.1925
2
1.1919
2
1.2744
5
1.3185
5
1.1836
2
1.1040
1
1.1040
1
1.2470
15
1.2404
18
1.2285
18
1.1008
1
1.2485
17
1.2122
14
1.1010
1
1.1331
1
1.1336
1
     
QCISD(T)=FULL         1.2599
11
  1.2584
11
1.1297
1
          1.2604
11
1.2447
11
1.2103
7
1.2612
11
1.2091
8
1.1709
6
    1.1276
2
1.1109
2
 
QCISD(TQ) 1.1939
1
1.1267
1
1.1267
1
1.1334
1
1.2001
7
1.1197
1
1.2195
6
1.1090
1
1.1090
1
1.1092
1
1.1030
1
1.1030
1
1.1046
1
1.2210
6
1.2100
5
1.0997
1
1.2222
6
1.1845
4
1.1000
1
         
QCISD(TQ)=FULL         1.2206
4
  1.2385
5
            1.2406
5
1.2250
5
  1.2416
5
1.2063
3
           
Coupled Cluster CCD 1.3237
7
1.2788
29
1.2655
28
1.2675
29
1.2970
37
1.2454
29
1.2449
29
1.2450
31
1.2308
24
1.2289
24
1.0944
1
1.0944
1
1.2313
15
1.2525
30
1.2244
23
1.0911
1
1.2014
15
1.1872
15
1.0913
1
1.1157
1
1.1159
1
1.1928
4
1.1790
4
 
CCSD 1.1891
1
1.1212
1
1.1212
1
1.1281
1
1.2652
26
1.1846
2
1.1839
2
1.2618
3
1.1688
4
1.2455
9
1.0964
1
1.0964
1
1.2367
15
1.2469
16
1.2437
17
1.1999
10
1.2463
15
1.2249
14
1.1705
8
1.1176
1
1.1177
1
     
CCSD=FULL 1.1890
1
1.1211
1
1.1211
1
1.1280
1
1.2553
16
1.1129
1
1.1126
1
1.1022
1
1.1022
1
1.2432
9
1.0946
1
1.0946
1
1.2357
14
1.2454
15
1.2394
16
1.1829
9
1.2455
15
1.2184
13
1.1662
7
1.1144
1
1.1138
1
     
CCSD(T) 1.1899
1
1.1271
1
1.1272
1
1.1335
1
1.2752
27
1.2577
6
1.1766
3
1.2508
6
1.3165
5
1.1832
2
1.1035
1
1.1035
1
1.2459
15
1.2379
25
1.2415
27
1.1988
12
1.2331
22
1.1998
19
1.1782
10
1.1320
1
1.1325
1
1.1819
6
1.1681
6
 
CCSD(T)=FULL 1.1898
1
1.1270
1
1.1270
1
1.1333
1
1.2451
19
1.1191
1
1.1189
1
1.1087
1
1.1087
1
1.1074
1
1.1017
1
1.1017
1
1.2453
15
1.2411
18
1.2305
17
1.1958
12
1.2289
12
1.2117
13
1.1845
9
1.1285
1
1.1283
1
1.1811
6
1.1662
6
 
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) 6-311+G(3df,2pd) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z aug-cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ Sadlej_pVTZ

average calculated bond lengths (Å)
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 1.2969
51
1.2771
51
1.2929
51
1.2689
51
1.2858
51
1.2858
51
density functional LSDA 1.1611
1
1.1432
1
1.1491
1
1.1219
1
1.1381
1
1.1381
1
SVWN 1.1611
1
1.1432
1
1.1491
1
1.1219
1
1.1381
1
1.1381
1
BLYP 1.1629
1
1.1440
1
1.1513
1
1.1220
1
1.1486
1
1.1491
1
B1B95 1.3595
32
1.3364
32
1.1708
2
1.1445
2
1.1663
2
1.1665
2
B3LYP 1.3390
51
1.3157
51
1.3345
51
1.3074
51
1.3258
51
1.3252
50
B3LYPultrafine 1.1488
1
1.1320
1
1.1376
1
1.1099
1
1.1333
1
1.1336
1
B3PW91 1.1465
1
1.1306
1
1.1351
1
1.1088
1
1.1307
1
1.1309
1
mPW1PW91 1.1433
1
1.1278
1
1.1320
1
1.1060
1
1.1276
1
1.1279
1
M06-2X 1.1375
1
1.1240
1
1.1243
1
1.0998
1
1.1239
1
1.1240
1
PBEPBE 1.1602
1
1.1424
1
1.1485
1
1.1212
1
1.1454
1
1.1457
1
PBEPBEultrafine 1.1602
1
1.1424
1
1.1485
1
1.1212
1
1.1454
1
1.1457
1
PBE1PBE 1.1438
1
1.1284
1
1.1326
1
1.1069
1
1.1282
1
1.1285
1
HSEh1PBE 1.1443
1
1.1288
1
1.1332
1
1.1074
1
1.1282
1
1.1285
1
wB97X-D 1.2425
1
1.2227
1
1.2331
1
1.2065
1
1.2270
1
1.2271
1
Moller Plesset perturbation MP2 1.3801
51
1.3286
51
1.3725
51
1.3213
51
1.3670
51
1.3672
51
MP2=FULL 1.1959
1
1.1598
1
1.1814
1
1.1378
1
1.1754
1
1.1752
1
MP3 1.1492
1
1.1338
1
1.1341
1
1.1110
1
1.1292
1
1.1288
1
MP4 1.1824
1
1.1551
1
1.1718
1
1.1344
1
1.1647
1
1.1650
1
MP4=FULL 1.1824
1
1.1551
1
1.1718
1
1.1344
1
1.1646
1
1.1647
1
B2PLYP 1.1637
1
1.1411
1
1.1518
1
1.1191
1
1.1469
1
1.1471
1
Configuration interaction CID 1.1524
1
1.1314
1
1.1381
1
1.1087
1
1.1331
1
1.1329
1
CISD 1.1542
1
1.1330
1
1.1399
1
1.1103
1
1.1349
1
1.1347
1
Quadratic configuration interaction QCISD 1.1653
1
1.1425
1
1.1510
1
1.1202
1
1.1457
1
1.1454
1
QCISD(T) 1.1695
1
1.1477
1
1.1559
1
1.1260
1
1.1500
1
1.1498
1
QCISD(TQ) 1.1700
1
1.1479
1
1.1559
1
1.1258
1
1.1502
1
1.1500
1
Coupled Cluster CCD 1.1619
1
1.1394
1
1.1475
1
1.1170
1
1.1422
1
1.1420
1
CCSD 1.1639
1
1.1414
1
1.1497
1
1.1191
1
1.1443
1
1.1441
1
CCSD=FULL 1.1639
1
1.1414
1
1.1497
1
1.1191
1
1.1442
1
1.1439
1
CCSD(T) 1.1692
1
1.1473
1
1.1556
1
1.1255
1
1.1497
1
1.1495
1
CCSD(T)=FULL 1.1692
1
1.1473
1
1.1556
1
1.1255
1
1.1495
1
1.1493
1
For descriptions of the methods (AM1, HF, MP2, ...) and basis sets (3-21G, 3-21G*, 6-31G, ...) see the glossary in section I.C. Predefined means the basis set used is determined by the method.