return to home page

III.G.1.a.

Comparison of levels of theory for C-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 1.5569
554
PM3 1.4951
1693
PM6 1.5456
1970
composite G2 1.4919
1558
G3 1.4977
1849
G3B3 1.4946
2033
G4 1.4625
1839
CBS-Q 1.4955
1189
molecular mechanics DREIDING 1.5414
17

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 1.4866
1845
1.4741
1945
1.4775
1840
1.4745
1855
1.4961
4678
1.4731
1850
1.4750
1922
1.4734
1846
1.4730
1851
1.4730
1819
1.4580
1311
1.4152
8
1.5362
2110
1.4750
1860
1.4710
1762
1.3938
245
1.4732
1645
1.4646
1566
1.3784
156
1.4031
18
1.3496
7
1.3425
7
1.4545
36
ROHF 1.3778
62
1.4143
138
1.4115
127
1.4010
118
1.4112
144
1.4098
130
1.4096
137
1.4072
137
1.4022
108
1.3830
64
1.3858
2
  1.4463
28
1.4106
137
1.4061
137
1.3865
56
1.4109
97
1.4028
83
1.3638
47
       
density functional LSDA 1.4916
1874
1.4711
1897
1.4722
1899
1.4701
1914
1.4659
1908
1.4658
1911
1.4660
1906
1.4614
1906
1.4624
1892
1.4644
1862
1.4037
10
1.4118
8
1.5444
323
1.4664
1903
1.4591
1899
1.3601
55
1.4653
1654
1.4401
172
1.3746
45
  1.3302
1
1.3209
1
 
SVWN 1.4245
10
1.5444
1892
1.4171
10
1.4171
10
1.5432
1874
1.5498
322
1.5413
1892
1.5461
322
1.5462
322
1.5483
317
1.4037
10
1.4118
8
1.4148
9
1.5521
322
1.5448
317
1.3421
3
1.5938
168
1.4805
118
1.3423
3
  1.3302
1
1.3209
1
 
BLYP 1.5201
1843
1.4957
1872
1.4949
1377
1.4949
1872
1.4908
1832
1.4903
1880
1.4925
1864
1.4873
1381
1.4896
1829
1.4938
1804
1.4251
10
1.4340
8
1.5683
324
1.4925
1828
1.4946
1857
1.3590
3
1.4861
1140
1.4249
10
1.3593
3
  1.3420
1
1.3333
1
 
B1B95 1.4965
1850
1.4799
1876
1.4804
1870
1.4784
1876
1.4761
1821
1.4748
1875
1.4743
1910
1.4720
1859
1.4730
1852
1.4748
1792
1.4079
10
1.4159
8
1.5454
337
1.4748
1864
1.4692
1856
1.3605
61
1.4759
1561
1.4365
287
1.3535
46
  1.3950
2
1.3889
2
 
B3LYP 1.5074
1866
1.5006
1931
1.4886
1874
1.4866
1882
1.4811
1952
1.4826
1892
1.4825
1958
1.4775
1869
1.4893
751
1.4841
1785
1.4756
1071
1.4231
8
1.5432
2151
1.4860
1887
1.4786
1845
1.3966
204
1.4794
852
1.4531
552
1.3846
157
1.4118
18
1.3608
7
1.3517
7
1.4625
36
B3LYPultrafine 1.4333
10
1.4061
11
1.4061
11
1.4064
11
1.4966
1682
1.4000
11
1.4464
251
1.3974
11
1.3974
11
1.3974
11
1.4147
10
1.4231
8
1.4292
22
1.6285
221
1.5191
734
1.3486
3
1.6452
143
1.4580
1698
1.3488
3
  1.3325
1
1.3240
1
 
B3PW91 1.5099
751
1.4823
1842
1.4835
1824
1.4813
1836
1.4786
1792
1.4790
1824
1.4775
1352
1.4749
1808
1.4915
697
1.4811
1763
1.4120
10
1.4201
8
1.5669
299
1.4784
1829
1.4737
1809
1.3471
3
1.4701
1143
1.4120
10
1.3472
3
  1.3313
1
1.3234
1
 
mPW1PW91 1.5012
822
1.4786
1865
1.4834
948
1.4773
1863
1.4746
1848
1.4737
1865
1.4746
1876
1.4717
1871
1.4721
1845
1.4772
1806
1.4102
10
1.4181
8
1.5555
318
1.4743
1862
1.4715
1114
1.3451
3
1.4883
1282
1.4845
131
1.3453
3
  1.3293
1
1.3216
1
 
M06-2X 1.5765
334
1.5659
330
1.5662
330
1.5618
334
1.5509
1891
1.5594
329
1.5593
334
1.5570
334
1.5568
334
1.5570
329
1.4115
10
1.4196
8
1.5712
295
1.5597
334
1.5537
334
1.3458
3
1.4769
178
1.4885
130
1.3460
3
  1.3288
1
1.3213
1
 
PBEPBE 1.5168
786
1.4944
1840
1.4986
802
1.4976
801
1.4838
1807
1.4832
1850
1.4844
1848
1.4810
1862
1.4814
1849
1.4862
1787
1.4773
1126
1.4283
8
1.5664
317
1.4846
1805
1.4857
1836
1.3927
60
1.5810
229
1.4774
323
1.3833
51
  1.3397
1
1.3323
1
1.4685
36
PBEPBEultrafine 1.4372
10
1.4333
10
1.4333
10
1.4315
10
1.4955
1930
1.4248
10
1.4272
10
1.4222
10
1.4224
10
1.4227
10
1.4199
10
1.4283
8
1.4344
22
1.6272
230
1.6239
225
1.3556
3
1.6504
143
1.5009
109
1.3558
3
  1.3397
1
1.3323
1
 
PBE1PBE 1.5846
308
1.5708
308
1.5708
308
1.5683
313
1.5460
1932
1.5639
313
1.5646
313
1.5614
313
1.5614
313
1.5617
313
1.4105
10
1.4184
8
1.5666
301
1.5653
313
1.5588
313
1.3457
3
1.6114
166
1.4873
118
1.3459
3
  1.3299
1
1.3226
1
 
HSEh1PBE 1.5805
329
1.5632
329
1.5636
329
1.5629
329
1.5510
1869
1.5587
329
1.5598
329
1.5567
329
1.5567
329
1.5569
329
1.4103
10
1.4182
8
1.5717
290
1.5602
329
1.5540
329
1.3457
3
1.5904
187
1.4891
125
1.3458
3
  1.3298
1
1.3223
1
 
TPSSh   1.4270
48
1.4270
48
1.4276
48
1.5632
2046
1.4222
48
1.5639
2038
1.4198
48
        1.4564
16
1.4239
48
1.5579
2039
  1.4201
33
1.4158
29
    1.3340
1
1.3265
1
 
Moller Plesset perturbation MP2 1.5202
752
1.4945
1899
1.4941
1812
1.4944
1816
1.4851
2187
1.4770
1827
1.4839
3880
1.4796
1788
1.4815
1796
1.4798
1216
1.4151
10
1.4256
8
1.5426
2128
1.4851
1847
1.4959
1713
1.3622
50
1.4880
796
1.4430
194
1.3489
46
1.4104
17
1.3486
10
1.3343
10
1.4661
36
MP2=FULL 1.5182
736
1.4934
1100
1.4983
954
1.4989
958
1.4817
2116
1.4751
1301
1.4760
1324
1.4788
1791
1.4981
663
1.4829
687
1.4116
10
1.4219
8
1.5638
310
1.4873
1089
1.4953
1254
1.3561
49
1.5402
294
1.4419
169
1.3582
48
1.4101
18
1.3475
10
1.3318
10
 
ROMP2 1.4150
66
1.3917
57
1.3918
57
1.3958
57
1.3810
55
1.3778
57
1.3807
55
1.3818
55
1.3827
55
1.3752
57
1.3833
2
  1.4480
23
1.3894
55
1.3737
52
1.2424
19
1.3792
54
1.2571
22
1.2372
19
       
MP3 1.4408
10
1.4332
10
1.4332
10
1.4351
10
1.4807
1728
1.4172
10
1.5598
2046
1.4208
10
1.4211
10
1.4168
10
1.4155
10
1.4251
8
1.4275
22
1.4400
22
1.4274
22
1.3490
3
1.4308
10
1.4160
10
1.1968
1
  1.3415
1
1.3281
1
 
MP3=FULL         1.5595
2041
  1.5610
1881
          1.4605
15
1.4719
15
1.4546
15
               
MP4 1.4163
29
1.4870
391
1.4767
25
1.4905
56
1.4734
475
1.4317
11
1.4339
11
1.4040
15
1.4547
254
1.3685
20
1.4211
10
1.4314
8
1.6560
87
1.6303
105
1.5012
144
1.3573
3
1.5292
80
1.4243
45
1.3577
3
  1.3494
1
1.3364
1
 
MP4=FULL 1.4430
10
1.6233
118
1.4394
10
1.4403
10
1.5894
124
1.4209
10
1.4236
10
1.4249
10
1.6415
95
1.4177
10
1.4175
10
1.4277
8
1.4296
9
1.6201
111
1.5984
73
1.3541
3
1.5234
83
1.4216
49
1.3543
3
  1.3484
1
1.3343
1
 
B2PLYP 1.5851
53
1.5675
53
1.5675
53
1.5702
53
1.5466
1667
1.5603
53
1.5623
53
1.5601
53
1.5603
53
1.5048
83
    1.5573
53
1.5650
53
1.5276
1703
  1.6159
40
1.6105
38
         
B2PLYP=FULL 1.5850
53
1.5674
53
1.5674
53
1.5701
53
1.5601
53
1.5597
53
1.5618
53
1.5596
53
1.5597
53
1.5565
53
    1.5570
53
1.5645
53
1.5545
53
  1.6154
40
1.6084
38
         
B2PLYP=FULLultrafine         1.4925
1150
                                   
Configuration interaction CID 1.3986
23
1.4947
755
1.5024
673
1.5028
676
1.4811
1260
1.4544
37
1.4565
21
1.4981
628
1.4149
34
1.3552
20
1.4097
10
1.4180
8
1.4207
9
1.4327
14
1.4183
11
1.3436
3
1.4243
10
1.4100
10
1.1917
1
  1.3356
1
1.3217
1
 
CISD 1.4084
24
1.4968
743
1.5033
677
1.5034
680
1.4922
1206
1.4995
25
1.4468
18
1.4968
645
1.4154
34
1.3647
19
1.4106
10
1.4187
8
1.4217
9
1.4386
15
1.4249
13
1.3446
3
1.4251
10
1.4108
10
1.1932
1
  1.3369
1
1.3230
1
 
Quadratic configuration interaction QCISD 1.4621
113
1.5135
1462
1.5171
748
1.5116
787
1.4886
1104
1.4886
789
1.4902
709
1.4936
874
1.4970
728
1.5223
409
1.4184
10
1.4265
8
1.5912
261
1.5036
693
1.5409
311
1.3513
3
1.5016
142
1.4315
85
1.2012
1
  1.3451
1
1.3309
1
 
QCISD(T) 1.4481
10
1.4648
13
1.4526
11
1.4517
11
1.4746
376
1.4335
11
1.4070
17
1.4093
16
1.4034
34
1.4235
10
1.4225
10
1.4310
8
1.4949
113
1.4678
195
1.4099
126
1.3560
3
1.4026
118
1.3906
67
1.3565
3
  1.3503
1
1.3364
1
 
QCISD(TQ) 1.4488
10
1.4425
10
1.4295
9
1.4317
9
1.4032
12
1.4245
10
1.4271
10
1.4163
9
1.4285
10
1.4240
8
1.4228
8
1.4337
2
1.4839
6
1.4349
10
1.3587
3
1.2060
1
1.4382
10
1.2596
3
         
Coupled Cluster CCD 1.4612
108
1.5082
786
1.5147
723
1.5125
770
1.4954
1293
1.4944
717
1.4956
652
1.4968
733
1.5208
438
1.4638
390
1.4156
10
1.4249
8
1.5868
262
1.5088
659
1.5463
296
1.3494
3
1.4552
178
1.3979
116
1.1983
1
  1.3985
5
1.3855
5
 
CCSD 1.4477
10
1.4609
13
1.4485
11
1.4484
11
1.5151
485
1.4298
11
1.4020
17
1.4034
15
1.3799
23
1.4195
10
1.4179
10
1.4260
8
1.6055
165
1.5620
252
1.5491
183
1.3513
12
1.4305
71
1.4104
47
1.2956
7
  1.3445
1
1.3303
1
 
CCSD=FULL 1.4474
10
1.4389
10
1.4389
10
1.4402
10
1.6697
179
1.4194
10
1.4217
10
1.4226
10
1.4228
10
1.4157
10
1.4144
10
1.3757
5
1.5613
149
1.6588
190
1.4144
118
1.3319
11
1.4379
72
1.3935
36
1.2908
7
  1.3435
1
1.3279
1
 
CCSD(T) 1.4482
10
1.4394
15
1.4524
11
1.4516
11
1.4716
440
1.4254
41
1.3790
22
1.3922
17
1.3865
27
1.3988
12
1.4065
11
1.4307
8
1.4949
108
1.4540
226
1.3893
146
1.3428
16
1.4013
132
1.3724
80
1.3508
15
  1.3510
11
1.3221
10
 
CCSD(T)=FULL 1.4479
10
1.4423
10
1.4423
10
1.4432
10
1.5056
219
1.4228
10
1.4253
10
1.4348
8
1.4268
10
1.4193
10
1.4186
10
1.4270
8
1.5945
120
1.5193
164
1.5339
106
1.3730
20
1.4398
94
1.4056
45
1.3430
13
  1.3499
11
1.3330
11
 

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 1.4949
1884
1.4907
1859
1.4872
1892
1.4814
1867
1.4820
1891
1.4816
1892
ROHF 1.4195
2
1.4140
2
1.4099
2
1.4001
2
1.4037
2
1.4034
2
density functional LSDA 1.4554
10
1.4478
10
1.4423
10
1.4313
10
1.4282
10
1.4280
10
SVWN 1.4554
10
1.4478
10
1.4423
10
1.4313
10
1.4282
10
1.4280
10
BLYP 1.4654
10
1.4571
10
1.4536
10
1.4420
10
1.4488
10
1.4491
10
B1B95 1.5018
1314
1.4960
1307
1.4645
41
1.4657
35
1.4578
41
1.4578
41
B3LYP 1.5093
1883
1.5031
1852
1.5008
1878
1.4935
1842
1.4937
1873
1.4942
1864
B3LYPultrafine 1.4867
13
1.4778
13
1.4761
13
1.4651
13
1.4702
13
1.4704
13
B3PW91 1.4511
10
1.4437
10
1.4386
10
1.4278
10
1.4336
10
1.4337
10
mPW1PW91 1.4487
10
1.4413
10
1.4361
10
1.4255
10
1.4313
10
1.4314
10
M06-2X 1.4480
10
1.4418
10
1.4336
10
1.4236
10
1.4318
10
1.4317
10
PBEPBE 1.4587
10
1.4511
10
1.4461
10
1.4354
10
1.4420
10
1.4423
10
PBEPBEultrafine 1.4587
10
1.4511
10
1.4461
10
1.4354
10
1.4420
10
1.4423
10
PBE1PBE 1.4485
10
1.4412
10
1.4359
10
1.4255
10
1.4313
10
1.4313
10
HSEh1PBE 1.4489
10
1.4417
10
1.4365
10
1.4261
10
1.4313
10
1.4313
10
Moller Plesset perturbation MP2 1.5228
1894
1.4999
1854
1.5135
1860
1.4912
1826
1.5082
1885
1.5077
1885
MP2=FULL 1.4725
10
1.4494
10
1.4565
10
1.4316
10
1.4543
10
1.4539
10
ROMP2 1.4359
2
1.4163
2
1.4212
2
1.3994
2
1.4180
2
1.4176
2
MP3 1.4719
10
1.4502
10
1.4556
10
1.4320
10
1.4530
10
1.4526
10
MP4 1.4763
10
1.4546
10
1.4607
10
1.4370
10
1.4578
10
1.4574
10
MP4=FULL 1.4763
10
1.4546
10
1.4607
10
1.4370
10
1.4575
10
1.4571
10
Configuration interaction CID 1.4664
10
1.4451
10
1.4504
10
1.4270
10
1.4477
10
1.4473
10
CISD 1.4674
10
1.4460
10
1.4514
10
1.4280
10
1.4488
10
1.4483
10
Quadratic configuration interaction QCISD 1.4774
10
1.4539
10
1.4612
10
1.4359
10
1.4585
10
1.4581
10
QCISD(T) 1.4801
10
1.4571
10
1.4641
10
1.4394
10
1.4612
10
1.4608
10
QCISD(TQ) 1.4807
10
1.4575
10
1.4644
10
1.4395
10
1.4617
10
1.4612
10
Coupled Cluster CCD 1.4745
10
1.4511
10
1.4582
10
1.4329
10
1.4555
10
1.4550
10
CCSD 1.4772
10
1.4535
10
1.4608
10
1.4354
10
1.4582
10
1.4577
10
CCSD=FULL 1.4772
10
1.4535
10
1.4608
10
1.4354
10
1.4579
10
1.4573
10
CCSD(T) 1.4801
10
1.4570
10
1.4640
10
1.4391
10
1.4611
10
1.4607
10
CCSD(T)=FULL 1.4801
10
1.4570
10
1.4640
10
1.4391
10
1.4608
10
1.4603
10
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.