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III.G.1.a.

Comparison of levels of theory for C-P


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 1.4716
4
PM3 1.5160
8
PM6 1.6105
8
composite G2 1.6309
7
G3 1.6289
8
G3B3 1.6415
8
G4 1.6392
6
CBS-Q 1.6295
8

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) 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
hartree fock HF 1.6431
7
1.6758
8
1.6287
7
1.6774
8
1.6503
14
1.6288
8
1.6298
8
1.6253
8
1.6253
8
1.6197
7
1.6486
5
1.6312
8
1.6357
8
1.6251
8
1.6200
7
1.6381
8
1.6256
8
1.6202
7
1.5997
4
1.6446
1
ROHF   1.5661
1
1.5249
1
  1.5522
2
1.5241
1
1.5252
1
1.5216
1
        1.5330
1
1.5221
1
           
density functional LSDA 1.6554
8
1.6563
8
1.6369
8
1.6793
8
1.6391
8
1.6389
8
1.6388
8
1.6324
8
1.6326
8
1.6311
8
  1.6687
1
1.6449
8
1.6302
8
1.5961
1
1.6449
8
1.6089
4
1.5944
1
1.6561
1
1.6562
1
SVWN   1.6771
8
    1.6510
7
1.6692
1
1.6387
8
1.6636
1
1.6639
1
1.6612
1
    1.6744
1
1.6609
1
  1.6755
1
1.6610
1
  1.6561
1
1.6562
1
BLYP 1.6673
7
1.6998
8
1.6573
8
1.7028
8
1.6602
8
1.6599
8
1.6603
8
1.6546
8
1.6547
8
1.6474
7
  1.6902
1
1.6650
8
1.6516
8
  1.6854
3
    1.6777
1
1.6779
1
B1B95 1.6240
8
1.6568
8
1.6328
8
1.6761
8
1.6333
8
1.6343
8
1.6342
8
1.6301
8
1.6302
8
1.6283
8
  1.6652
1
1.6403
8
1.6275
8
1.5679
2
1.6400
8
1.6057
4
1.5675
2
1.6544
1
1.6547
1
B3LYP 1.6465
8
1.6820
8
1.6394
8
1.6845
8
1.6417
8
1.6415
8
1.6420
8
1.6368
8
1.6135
4
1.6297
7
1.7075
2
1.6405
8
1.6472
8
1.6345
8
1.6375
6
1.6481
8
1.6345
8
1.6375
6
1.6028
4
1.6629
1
B3LYPultrafine         1.6417
8
  1.8768
1
          1.6783
1
1.7681
2
  1.6803
1
1.6282
7
  1.6626
1
1.6629
1
B3PW91 1.6197
5
1.6901
7
1.6368
8
1.6913
7
1.6381
8
1.6379
8
1.6379
8
1.6330
8
1.6103
4
1.6268
7
  1.6713
1
1.6438
8
1.6315
8
  1.6635
3
    1.6596
1
1.6598
1
mPW1PW91 1.6207
6
1.6756
8
1.6221
5
1.6770
8
1.6344
8
1.6343
8
1.6343
8
1.6297
8
1.6299
8
1.6234
7
  1.6683
1
1.6400
8
1.6283
8
  1.6636
4
1.6614
1
  1.6567
1
1.6570
1
M06-2X 1.6408
1
1.6927
1
1.6593
1
1.6962
1
1.6298
8
1.6634
1
1.6652
1
1.6602
1
1.6603
1
1.6562
1
  1.6644
1
1.6678
1
1.6581
1
  1.6700
1
1.6583
1
  1.6543
1
1.6546
1
PBEPBE 1.6283
4
1.6939
8
1.6418
5
1.6867
5
1.6536
8
1.6534
8
1.6533
8
1.6483
8
1.6484
8
1.6421
7
1.6648
5
1.6849
1
1.6588
8
1.6463
8
1.5856
2
1.6338
2
1.6522
6
1.5849
2
1.6200
2
1.6733
1
PBEPBEultrafine         1.7069
7
              1.6885
1
1.6775
1
  1.6911
1
1.6778
1
  1.6732
1
1.6733
1
PBE1PBE 1.6490
1
1.6642
1
1.6642
1
1.7033
1
1.6350
8
1.6684
1
1.6695
1
1.6638
1
1.6640
1
1.6610
1
  1.6691
1
1.6725
1
1.6619
1
  1.6744
1
1.6622
1
  1.6576
1
1.6579
1
HSEh1PBE 1.6498
1
1.7012
1
1.6644
1
1.7041
1
1.6479
7
1.6684
1
1.6701
1
1.6643
1
1.6645
1
1.6615
1
  1.6696
1
1.6731
1
1.6623
1
  1.6750
1
1.6627
1
  1.6580
1
1.6582
1
TPSSh         1.6366
7
  1.6362
7
            1.6306
7
        1.6641
1
1.6645
1
Moller Plesset perturbation MP2 1.6778
5
1.7067
8
1.6485
8
1.7103
8
1.6580
11
1.6432
8
1.6850
12
1.6386
8
1.6388
8
1.6202
6
  1.6455
8
1.6565
8
1.6510
10
1.5912
3
1.6595
8
1.6385
8
1.5873
2
1.6010
4
1.6695
1
MP2=FULL 1.6776
5
1.7068
8
1.6430
5
1.7052
5
1.6561
11
1.6412
8
1.6413
8
1.6374
8
1.6237
4
1.6179
4
  1.6796
1
1.6551
8
1.6506
8
1.5862
3
1.6096
4
1.6341
2
1.6618
1
1.5949
4
1.6629
1
MP3         1.6320
8
  1.6449
7
                      1.6640
1
1.6650
1
MP3=FULL         1.6440
7
  1.6474
7
                      1.6584
1
1.6590
1
MP4 1.6790
2
1.7085
4
    1.6650
7
    1.6654
5
1.6367
4
    1.6915
1
1.6968
1
1.6169
6
  1.7021
1
1.6830
1
  1.6778
1
1.6786
1
MP4=FULL   1.7329
1
    1.6859
1
      1.6820
1
      1.6951
1
1.6766
1
  1.6996
1
1.6774
1
  1.6718
1
1.6722
1
B2PLYP 1.6620
1
1.7134
1
1.6716
1
1.7182
1
1.6421
8
1.6754
1
1.6776
1
1.6716
1
1.6719
1
1.6688
1
  1.6779
1
1.6819
1
1.6280
7
  1.6857
1
1.6709
1
  1.6657
1
1.6661
1
B2PLYP=FULL 1.6620
1
1.7134
1
1.6714
1
1.7181
1
1.6755
1
1.6747
1
1.6770
1
1.6713
1
1.6716
1
1.6674
1
  1.6777
1
1.6814
1
1.6686
1
  1.6849
1
1.6692
1
  1.6639
1
1.6644
1
B2PLYP=FULLultrafine         1.7714
2
                             
Configuration interaction CID   1.6704
4
1.6127
4
1.6749
4
1.6311
8
    1.6267
8
                    1.6540
1
1.6547
1
CISD   1.6524
5
1.6152
4
1.6648
3
1.6343
8
1.5379
1
  1.6079
4
                    1.6560
1
1.6566
1
Quadratic configuration interaction QCISD 1.6831
2
1.7037
8
1.6383
5
1.6761
5
1.6460
8
1.6352
5
1.6456
8
1.6422
8
1.6373
7
1.6175
4
  1.6831
1
1.6586
8
1.6184
6
  1.6935
1
1.6731
1
  1.6141
2
1.6687
1
QCISD(T)         1.6683
6
    1.6725
5
      1.6917
1
1.6479
4
1.6291
4
  1.6476
3
1.6266
3
  1.6770
1
1.6777
1
Coupled Cluster CCD 1.6827
2
1.6891
5
1.6326
5
1.6941
5
1.6374
8
1.6284
5
1.6285
5
1.6329
8
1.6133
4
1.6104
4
  1.6771
1
1.6638
7
1.6225
5
  1.6346
4
1.6114
4
  1.6632
1
1.6639
1
CCSD         1.6593
6
    1.6648
5
      1.6815
1
1.6879
1
1.6710
1
1.6644
1
1.6922
1
1.6718
1
1.6649
1
1.6669
1
1.6675
1
CCSD=FULL         1.6774
1
            1.6807
1
1.6863
1
1.6656
1
1.6599
1
1.6897
1
1.6661
1
  1.6608
1
1.6611
1
CCSD(T)   1.6285
1
    1.6757
5
1.6747
5
1.5756
1
1.6718
5
1.5712
1
  1.5624
1
1.6912
1
1.6472
4
1.6166
5
1.6220
2
1.6501
4
1.6285
4
1.6750
1
1.6209
2
1.6773
1
CCSD(T)=FULL         1.6478
3
            1.6905
1
1.6955
1
1.6754
1
1.6699
1
1.6996
1
1.6760
1
1.6694
1
1.6706
1
1.6709
1

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 1.6885
8
1.6506
8
1.6863
8
1.6439
8
1.6935
6
1.6698
8
density functional B1B95 1.7144
5
1.7140
3
       
B3LYP 1.7010
8
1.6627
8
1.6986
8
1.6585
8
1.7150
6
1.6774
8
Moller Plesset perturbation MP2 1.7302
8
1.6727
8
1.7216
8
1.6617
8
1.7787
6
1.7051
8
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.