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III.G.1.a.

Comparison of levels of theory for N-C


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 1.3298
120
PM3 1.3728
295
PM6 1.3835
335
composite G2 1.3601
289
G3 1.3501
319
G3B3 1.3555
360
G4 1.3479
342
CBS-Q 1.3185
226
molecular mechanics DREIDING 1.4603
6

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 cc-pCVDZ cc-pCVTZ Sadlej_pVTZ
hartree fock HF 1.3769
332
1.3353
350
1.3350
330
1.3327
330
1.3517
804
1.3245
332
1.3351
346
1.3235
331
1.3342
329
1.3314
331
1.3352
212
1.3096
5
1.3569
361
1.3270
330
1.3201
323
1.2877
87
1.3268
305
1.3211
299
1.2858
69
1.2198
5
1.2242
2
1.2162
2
1.4140
8
ROHF 1.2793
12
1.2671
28
1.2513
26
1.2558
26
1.2530
29
1.2398
26
1.2371
26
1.2328
26
1.2531
27
1.2312
13
    1.2731
14
1.2447
25
1.2342
25
1.2438
16
1.2630
26
1.2548
26
1.2297
15
       
density functional LSDA 1.3937
327
1.3505
334
1.3510
335
1.3492
333
1.3407
333
1.3403
333
1.3396
332
1.3350
331
1.3364
331
1.3373
329
    1.3201
78
1.3410
330
1.3333
330
1.2913
10
1.3407
305
1.2988
67
1.2824
8
       
SVWN   1.3767
321
    1.3708
311
1.3265
78
1.3684
318
1.3215
78
1.3216
78
1.3230
78
      1.3273
78
1.3194
78
  1.3208
52
1.3131
52
         
BLYP 1.4247
324
1.3745
326
1.3623
241
1.3625
323
1.3536
320
1.3533
326
1.3535
323
1.3468
240
1.3613
321
1.3599
320
    1.3415
78
1.3552
320
1.3471
324
  1.3842
179
           
B1B95 1.4006
344
1.3600
348
1.3602
348
1.3583
350
1.3477
330
1.3485
348
1.3483
344
1.3450
347
1.3459
347
1.3484
338
1.2871
1
  1.3310
84
1.3491
346
1.3421
345
1.2577
15
1.3537
308
1.3338
106
1.2439
13
       
B3LYP 1.4081
336
1.3530
347
1.3526
329
1.3507
330
1.3536
350
1.3509
332
1.3430
347
1.3379
326
1.3310
165
1.3391
319
1.3617
172
1.3214
5
1.3705
360
1.3555
331
1.3357
324
1.3019
70
1.3362
174
1.3312
163
1.2873
63
1.2448
5
    1.4252
8
B3LYPultrafine   1.3296
3
    1.3559
325
  1.3299
59
        1.3228
3
1.2969
25
1.3443
51
1.3445
142
  1.3247
43
1.3413
322
         
B3PW91 1.3769
158
1.3469
324
1.3472
323
1.3446
323
1.3363
321
1.3357
325
1.3328
241
1.3341
322
1.3225
159
1.3432
320
    1.3255
78
1.3370
324
1.3299
322
  1.3667
178
           
mPW1PW91 1.3771
174
1.3436
323
1.3395
176
1.3518
326
1.3332
319
1.3357
324
1.3326
324
1.3293
324
1.3414
323
1.3405
320
    1.3207
76
1.3359
319
1.3224
200
  1.3533
231
1.3092
55
         
M06-2X 1.3800
85
1.3509
85
1.3514
85
1.3472
85
1.3709
337
1.3367
85
1.3370
85
1.3340
85
1.3341
85
1.3337
85
    1.3318
82
1.3374
85
1.3321
85
  1.3355
59
1.3297
59
         
PBEPBE 1.3903
159
1.3674
324
1.3468
161
1.3458
160
1.3566
318
1.3561
318
1.3560
321
1.3532
320
1.3549
323
1.3630
316
1.3727
167
1.3282
5
1.3341
76
1.3551
306
1.3509
317
1.2790
14
1.3315
66
1.3265
100
1.2601
13
1.1682
1
    1.4277
8
PBEPBEultrafine   1.3371
3
    1.3684
324
  1.3397
6
        1.3291
3
1.3073
25
1.3518
51
1.3451
51
  1.3331
43
1.3265
46
         
PBE1PBE 1.3739
67
1.3388
67
1.3388
67
1.3368
67
1.3645
330
1.3255
67
1.3253
67
1.3217
67
1.3218
67
1.3226
67
    1.3173
65
1.3259
67
1.3196
67
  1.3210
49
1.3145
49
         
HSEh1PBE 1.3853
85
1.3489
85
1.3494
85
1.3477
85
1.3642
323
1.3362
85
1.3364
85
1.3331
85
1.3331
85
1.3336
85
    1.3311
82
1.3369
85
1.3309
85
  1.3353
59
1.3289
59
         
TPSSh   1.3625
39
1.3625
39
1.3578
39
1.3658
360
1.3421
39
1.3661
360
1.3385
39
        1.3337
31
1.3430
39
1.3604
360
  1.3117
31
1.3313
37
         
Moller Plesset perturbation MP2 1.3881
168
1.3668
353
1.3656
328
1.3651
330
1.3558
401
1.3448
332
1.3668
704
1.3426
318
1.3448
326
1.3316
252
  1.3234
2
1.3735
361
1.3598
330
1.3348
300
1.2791
30
1.3435
172
1.3136
86
1.2435
28
1.3028
3
1.2065
4
1.1913
4
1.4311
8
MP2=FULL 1.3846
164
1.3609
208
1.3611
184
1.3592
184
1.3631
377
1.3386
242
1.3412
247
1.3409
329
1.3317
162
1.3223
163
    1.3383
84
1.3447
208
1.3312
232
1.2760
32
1.3355
103
1.3192
70
1.2868
32
1.2442
5
1.2058
4
1.1892
4
 
ROMP2 1.3176
23
1.2815
22
1.2815
22
1.2872
23
1.2670
22
1.2642
23
1.2622
23
1.2566
23
1.2567
23
1.2584
23
    1.2874
14
1.2718
22
1.2477
20
1.1927
3
1.2710
22
1.1949
4
1.1923
3
       
MP3         1.3387
318
  1.3583
356
          1.2933
25
1.3048
25
1.2926
25
               
MP3=FULL         1.3643
359
  1.3604
328
          1.3264
31
1.3367
31
1.3214
31
               
MP4 1.3376
6
1.3522
132
1.3825
4
1.3388
3
1.3373
148
    1.2478
5
1.3265
113
1.2519
4
    1.3273
38
1.3344
43
1.2900
73
  1.3401
42
1.3102
33
         
MP4=FULL   1.3631
46
    1.3258
41
      1.3268
43
        1.3425
46
1.3210
38
  1.3389
42
1.3239
35
         
B2PLYP 1.4219
24
1.3916
24
1.3916
24
1.3888
24
1.3874
268
1.3685
24
1.3696
24
1.3663
24
1.3665
24
1.3652
24
    1.3649
24
1.3701
24
1.3670
282
  1.3668
22
1.3589
22
         
B2PLYP=FULL 1.4218
24
1.3916
24
1.3916
24
1.3887
24
1.3681
24
1.3680
24
1.3691
24
1.3658
24
1.3660
24
1.3638
24
    1.3645
24
1.3697
24
1.3620
24
  1.3664
22
1.3574
22
         
B2PLYP=FULLultrafine         1.3794
189
                                   
Configuration interaction CID 1.3923
2
1.3362
167
1.3394
165
1.3378
166
1.3279
238
1.3529
5
1.3535
5
1.3191
164
1.2615
8
1.2308
4
      1.3565
5
                 
CISD 1.4538
6
1.3413
172
1.3414
165
1.3400
166
1.3270
232
1.3990
9
1.3541
5
1.3205
161
1.2623
8
1.2315
4
      1.3570
5
                 
Quadratic configuration interaction QCISD 1.2957
16
1.3710
262
1.3582
161
1.3517
168
1.3418
217
1.3261
162
1.3265
165
1.3322
190
1.3207
186
1.3128
114
    1.3344
78
1.3332
166
1.2950
99
  1.3326
54
1.3095
48
  1.1584
1
     
QCISD(T)         1.3193
128
  1.3099
2
1.3187
7
1.2912
5
      1.3392
60
1.3207
78
1.3173
67
  1.3409
54
1.3257
41
         
Coupled Cluster CCD 1.2933
16
1.3477
161
1.3566
160
1.3522
162
1.3507
251
1.3268
155
1.3312
155
1.3284
164
1.3188
115
1.3163
111
    1.3433
78
1.3305
154
1.3094
91
  1.3029
58
1.2975
47
         
CCSD         1.3240
127
  1.3315
2
1.1913
4
1.3028
1
      1.3301
43
1.3282
67
1.3229
61
1.2574
13
1.3547
38
1.3195
32
1.2544
11
       
CCSD=FULL         1.3488
48
              1.3437
48
1.3536
51
1.3159
43
1.2569
12
1.3705
44
1.3002
27
1.2539
10
       
CCSD(T)   1.1845
3
    1.3214
135
1.3191
11
1.2221
6
1.2524
5
1.2459
8
  1.1731
1
  1.3309
55
1.3181
90
1.3044
86
1.2408
19
1.3239
74
1.3064
56
1.2518
15
1.1658
1
1.2126
4
1.1981
4
 
CCSD(T)=FULL         1.3014
75
              1.3420
56
1.3129
68
1.3138
68
1.2433
18
1.3403
53
1.3266
42
1.2416
15
  1.2118
4
1.1893
5
 

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 1.3490
330
1.3386
328
1.3454
330
1.3326
328
1.3406
330
1.3406
330
ROHF 1.1703
1
  1.1645
1
  1.1621
1
1.1615
1
density functional B1B95 1.3836
210
1.3768
204
1.4393
5
1.4315
5
1.4363
5
1.4363
5
B3LYP 1.3691
328
1.3575
326
1.3647
329
1.3511
327
1.3587
329
1.3593
325
B3LYPultrafine 1.5066
6
1.4859
6
1.5020
6
1.4829
6
1.4942
6
1.4942
6
Moller Plesset perturbation MP2 1.3888
331
1.3621
327
1.3812
332
1.3561
327
1.3785
332
1.3788
331
ROMP2 1.2362
1
  1.2246
1
  1.2224
1
1.2224
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.