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Release 18October 2016
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 1.2273
29
PM3 1.3972
33
PM6 1.2808
61
composite G2 1.2559
52
G3 1.2608
55
G3B3 1.2986
58
G3MP2 1.1534
5
G4 1.2793
62
CBS-Q 1.2325
41

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 daug-cc-pVTZ Sadlej_pVTZ
hartree fock HF 1.3320
58
1.2938
54
1.2902
55
1.2744
55
1.2566
62
1.2606
55
1.2150
29
1.2582
55
1.2603
58
1.2600
58
1.2876
32
1.0665
1
1.2511
62
1.2606
55
1.2471
53
1.2150
19
1.2616
55
1.2502
53
1.2208
17
1.0762
1
1.0760
1
1.1380
6
1.1296
6
1.0670
2
1.0846
2
ROHF 1.2802
1
1.1801
6
1.1800
5
1.1966
4
1.1682
6
1.1681
5
1.1654
5
1.1629
5
1.1820
4
1.1913
1
    1.1781
4
1.1673
5
1.1591
5
1.1764
4
1.1838
4
1.1548
4
1.1536
4
        1.0670
1
 
density functional LSDA 1.3889
59
1.3258
58
1.3257
58
1.3079
59
1.2907
59
1.2925
58
1.2910
58
1.2857
59
1.2877
58
1.2886
58
1.0944
1
1.0944
1
1.2259
25
1.2916
58
1.2846
58
1.1435
2
1.2915
57
1.2175
25
1.1400
2
1.1319
1
1.1319
1
    1.1085
2
 
SVWN 1.1890
1
1.3112
60
1.1181
1
1.1229
1
1.2894
59
1.2357
25
1.2845
60
1.2289
25
1.2288
25
1.2313
25
1.0944
1
1.0944
1
1.3243
46
1.2348
25
1.2257
25
1.0939
1
1.2322
24
1.2227
24
1.0937
1
1.1319
1
1.1319
1
    1.1085
2
 
BLYP 1.4356
58
1.3616
58
1.3242
41
1.3391
55
1.3049
63
1.3207
55
1.3191
55
1.2855
41
1.3184
58
1.3186
58
1.1031
1
1.1031
1
1.2475
25
1.3224
54
1.3126
55
1.1022
1
1.3250
39
1.2401
15
1.1021
1
1.1400
1
1.1400
1
    1.1109
2
 
B1B95 1.3985
58
1.3241
58
1.3240
58
1.3075
58
1.2886
58
1.2898
58
1.2887
58
1.2865
58
1.2864
58
1.2863
58
1.1084
2
1.0878
1
1.2220
25
1.2890
58
1.2819
58
1.1511
3
1.2880
57
1.2487
33
1.1383
3
1.1165
1
1.1164
1
    1.0879
2
 
B3LYP 1.3955
57
1.3323
54
1.3292
55
1.3145
55
1.2998
58
1.2995
58
1.2962
55
1.2937
55
1.2524
34
1.2937
55
1.3274
27
1.0912
1
1.2820
62
1.2986
58
1.2837
52
1.2472
17
1.2585
36
1.2948
55
1.2448
17
1.1217
1
1.1217
1
1.1722
5
1.1618
5
1.0999
2
1.1218
2
B3LYPultrafine 1.1807
1
1.2741
19
1.1127
1
1.1184
1
1.3037
56
1.2463
19
1.3005
24
1.2405
19
1.0954
1
1.0988
1
1.0912
1
1.0912
1
1.2331
21
1.2375
25
1.2563
35
1.0902
1
1.2356
24
1.2771
61
1.0901
1
        1.0927
2
 
B3PW91 1.3526
35
1.3249
55
1.3250
55
1.3090
55
1.2882
53
1.2916
55
1.2629
41
1.2879
55
1.2480
34
1.2903
58
1.0910
1
1.0910
1
1.2262
25
1.2911
55
1.2849
55
1.0901
1
1.2973
39
1.2193
15
1.0901
1
1.1215
1
1.1214
1
    1.0911
2
 
mPW1PW91 1.3427
35
1.3199
55
1.2764
35
1.3071
58
1.2848
52
1.3286
55
1.2860
55
1.2836
55
1.2858
58
1.2859
58
1.0888
1
1.0888
1
1.2225
24
1.2865
55
1.2450
38
1.0880
1
1.2808
50
1.2150
25
1.0879
1
1.1178
1
1.1178
1
    1.0956
2
 
M06-2X 1.3071
25
1.2556
25
1.2710
50
1.2408
25
1.2787
61
1.2285
25
1.2272
25
1.2242
25
1.2244
25
1.2315
27
1.0862
1
1.0862
1
1.2206
24
1.2280
25
1.2284
27
1.0854
1
1.2270
24
1.2269
26
1.0853
1
1.1105
1
1.1102
1
    1.0884
2
 
PBEPBE 1.3697
35
1.3517
58
1.3030
34
1.2857
34
1.3122
58
1.3119
58
1.3104
58
1.3078
58
1.3081
58
1.3049
56
1.3262
30
1.1031
1
1.2395
24
1.3132
56
1.3052
58
1.1682
3
1.2406
25
1.2346
30
1.1529
3
1.1395
1
1.1396
1
    1.1146
2
1.1319
2
PBEPBEultrafine 1.1954
1
1.2897
19
1.1273
1
1.1303
1
1.3126
54
1.2567
19
1.2541
19
1.2518
19
1.1072
1
1.1109
1
1.1031
1
1.1031
1
1.2446
21
1.2485
25
1.2402
25
1.1024
1
1.2460
24
1.2370
24
1.1022
1
        1.1145
2
 
PBE1PBE 1.3152
25
1.2568
25
1.2570
25
1.2443
25
1.2812
62
1.2312
25
1.2292
25
1.2261
25
1.2260
25
1.2273
25
1.0898
1
1.0898
1
1.2226
24
1.2301
25
1.2232
25
1.0889
1
1.2285
24
1.2208
24
1.0889
1
1.1188
1
1.1188
1
    1.0968
2
 
HSEh1PBE 1.3159
25
1.3105
61
1.2589
25
1.2454
25
1.2823
60
1.2310
25
1.2812
61
1.2261
25
1.2261
25
1.2272
25
1.0894
1
1.0894
1
1.2225
24
1.2302
25
1.2766
61
1.0885
1
1.2286
24
1.2205
24
1.0885
1
1.1187
1
1.1187
1
    1.0959
2
 
TPSSh 1.3191
10
1.2765
24
1.2765
24
1.2604
24
1.2904
62
1.2462
24
1.2899
62
1.2409
24
1.2172
10
1.2837
57
    1.2372
21
1.2456
24
1.2844
62
1.2447
3
1.2436
23
1.2354
23
1.2334
3
        1.1049
2
 
wB97X-D 1.3033
11
1.2266
11
1.3087
64
1.2182
11
1.2851
64
1.2113
11
1.2845
64
1.2058
11
1.2815
64
1.2055
11
    1.2797
64
1.2849
64
1.2790
64
1.2215
4
1.2093
11
1.2792
63
1.1972
4
        1.0883
2
 
B97D3 1.3433
3
1.3369
57
1.2987
3
1.2742
3
1.3110
57
1.2595
3
1.2541
3
1.2533
3
1.3076
57
1.2548
3
    1.2501
3
1.2577
3
1.2499
3
1.2478
3
1.2527
3
1.3054
56
1.2339
3
        1.1086
2
 
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 daug-cc-pVTZ Sadlej_pVTZ
Moller Plesset perturbation MP2 1.3728
35
1.3677
55
1.3679
55
1.3501
55
1.3194
63
1.3117
55
1.3124
58
1.3145
62
1.3054
55
1.3005
54
1.1131
1
1.1131
1
1.2917
62
1.3134
58
1.2800
46
1.2211
13
1.2785
36
1.2586
30
1.2194
13
1.1588
1
1.1600
1
1.1826
7
1.1690
7
1.1143
2
1.1484
2
MP2=FULL 1.3731
34
1.3290
38
1.3268
35
1.3111
35
1.3076
56
1.2826
40
1.2832
41
1.3034
55
1.2656
34
1.2648
36
1.1111
1
1.1111
1
1.2424
25
1.2781
38
1.2596
36
1.2181
13
1.2565
32
1.2254
31
1.2162
13
1.1545
1
1.1547
1
1.1818
7
1.1669
7
1.1110
2
1.1476
2
ROMP2 1.3255
4
1.2604
4
1.2604
4
1.2492
4
1.2262
4
1.2256
4
1.2211
4
1.2193
4
1.2194
4
1.2171
4
    1.2139
4
1.2260
4
1.2132
4
1.1813
1
1.2220
4
1.1812
1
1.1786
1
        1.1145
1
 
MP3 1.1757
1
1.1088
1
1.1088
1
1.1149
1
1.2914
55
1.1057
1
1.2834
62
1.0949
1
1.0949
1
1.0961
1
1.0895
1
1.0895
1
1.2296
21
1.2394
21
1.2276
21
1.0865
1
1.1067
1
1.0899
1
1.0867
1
  1.1109
1
    1.0900
2
 
MP3=FULL   1.2326
11
1.2326
11
1.2231
11
1.2824
62
1.2119
11
1.2819
61
1.2045
11
1.2051
11
1.2020
11
    1.2287
21
1.2387
21
1.2229
21
  1.2131
11
1.1943
11
          1.0866
2
 
MP4 1.2530
3
1.3020
29
1.1403
1
1.1470
1
1.2868
36
1.1282
1
1.1285
1
1.2795
2
1.2816
31
1.3190
6
1.1131
1
1.1131
1
1.2506
24
1.2580
24
1.2697
28
1.1102
1
1.2623
22
1.2353
19
1.1104
1
1.1571
1
1.1580
1
    1.1140
2
 
MP4=FULL 1.1903
1
1.3031
24
1.1402
1
1.1469
1
1.2601
22
1.1275
1
1.1278
1
1.1182
1
1.2548
22
1.1155
1
1.1112
1
1.1112
1
1.1144
1
1.2602
22
1.2458
22
1.1079
1
1.2614
22
1.2234
18
1.1080
1
1.1527
1
1.1525
1
    1.1097
2
 
B2PLYP 1.3324
23
1.2800
23
1.2800
23
1.2659
23
1.2985
58
1.2469
23
1.2453
23
1.2408
23
1.2415
23
1.2470
25
1.0992
1
1.0992
1
1.2385
23
1.2463
23
1.2892
59
1.0978
1
1.2452
22
1.2422
24
1.0978
1
        1.0998
2
 
B2PLYP=FULL 1.3323
23
1.2760
23
1.2799
23
1.2658
23
1.2457
23
1.2466
23
1.2439
23
1.2404
23
1.2412
23
1.2401
23
    1.2376
23
1.2461
23
1.2356
23
  1.2449
22
1.2337
22
          1.0987
2
 
B2PLYP=FULLultrafine 1.3295
12
1.2598
12
1.2598
12
1.2461
12
1.3040
38
1.2328
12
1.2301
12
1.2271
12
1.2272
12
1.2265
12
    1.2239
12
1.2330
12
1.2219
12
  1.2308
12
1.2189
12
          1.0987
2
 
Configuration interaction CID 1.2613
4
1.2738
34
1.2633
32
1.2508
32
1.2567
39
1.1040
1
1.1036
1
1.2306
33
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
    1.0874
2
 
CISD 1.2621
4
1.2748
34
1.2640
32
1.2532
32
1.2535
38
  1.1053
1
1.2262
32
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
    1.0889
2
 
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 daug-cc-pVTZ Sadlej_pVTZ
Quadratic configuration interaction QCISD 1.3775
5
1.3266
42
1.2867
30
1.2848
32
1.2669
39
1.2672
35
1.2660
35
1.2577
35
1.2582
35
1.2460
31
    1.2346
23
1.2673
33
1.2431
30
  1.2395
25
1.2189
23
  1.1195
1
1.1195
1
    1.0993
2
 
QCISD(T) 1.1900
1
1.1278
1
1.1278
1
1.1339
1
1.2744
32
1.1925
2
1.1919
2
1.2594
12
1.3507
4
1.1836
2
1.1040
1
1.1040
1
1.2440
24
1.2498
23
1.2354
25
1.1008
1
1.2570
22
1.2278
19
1.1010
1
1.1331
1
1.1336
1
    1.1046
2
 
QCISD(T)=FULL         1.2535
20
  1.2521
20
1.1297
1
          1.2545
20
1.2422
18
1.2341
9
1.2592
18
1.2212
15
1.2053
8
    1.1276
2
1.1109
2
1.1007
2
 
QCISD(TQ) 1.1939
1
1.1267
1
1.1267
1
1.1334
1
1.1907
10
1.1197
1
1.2015
9
1.1090
1
1.1090
1
1.1092
1
1.1030
1
1.1030
1
1.1046
1
1.2039
9
1.1891
8
1.1474
2
1.2040
9
1.1848
5
1.1390
2
           
QCISD(TQ)=FULL         1.1980
7
  1.2107
8
            1.2137
8
1.1967
8
1.1923
1
1.2135
8
1.1996
4
1.1749
1
           
Coupled Cluster CCD 1.3659
5
1.2893
33
1.2780
32
1.2762
33
1.2992
41
1.2543
33
1.2538
33
1.2527
35
1.2379
30
1.2354
30
    1.2284
24
1.2603
34
1.2317
29
  1.2197
22
1.2051
22
  1.1157
1
1.1159
1
1.1928
4
1.1790
4
1.0948
2
 
CCSD         1.2651
32
1.2557
1
1.2545
1
1.3412
2
1.1946
2
1.2361
18
    1.2331
24
1.2433
25
1.2369
26
1.2185
12
1.2429
24
1.2238
23
1.1705
9
1.1176
1
1.1177
1
    1.0968
2
 
CCSD=FULL         1.2481
25
        1.2335
18
    1.2320
23
1.2419
24
1.2320
25
1.2057
11
1.2421
24
1.2176
22
1.1663
8
1.1144
1
1.1138
1
    1.0931
2
 
CCSD(T) 1.1899
1
1.1271
1
1.1272
1
1.1335
1
1.2751
32
1.2507
15
1.2380
5
1.2490
13
1.3426
6
1.2555
4
1.1035
1
1.1035
1
1.2459
22
1.2427
27
1.2504
30
1.2177
13
1.2463
25
1.2175
22
1.2025
11
1.1320
1
1.1325
1
1.1819
6
1.1681
6
1.1041
2
 
CCSD(T)=FULL 1.1898
1
1.1270
1
1.1270
1
1.1333
1
1.2486
25
1.1191
1
1.1189
1
1.1087
1
1.1087
1
1.1074
1
1.1017
1
1.1017
1
1.2452
22
1.2448
25
1.2324
24
1.2146
13
1.2385
19
1.2195
20
1.2101
10
1.1285
1
1.1283
1
1.1811
6
1.1662
6
1.1002
2
 
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 daug-cc-pVTZ 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 1.2940
55
1.2773
55
1.2901
55
1.2694
55
1.2834
55
1.2834
55
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 1.3639
31
1.3408
31
1.1310
1
1.1057
1
1.1265
1
1.1267
1
B3LYP 1.3371
55
1.3158
55
1.3326
55
1.3075
55
1.3239
55
1.3232
54
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 1.2436
11
1.2331
11
1.2358
11
1.2193
11
1.2289
11
1.2291
11
Moller Plesset perturbation MP2 1.3825
55
1.3314
55
1.3750
55
1.3240
55
1.3691
55
1.3694
55
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(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 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.