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Comparison of levels of theory for K-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 PM3 2.7990
2
PM6 3.0107
3
composite G2 2.7444
2
G3 2.7410
2
G3B3 2.9616
3
G4 2.9727
3
CBS-Q 2.7440
2

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
hartree fock HF 2.9096
3
3.1598
3
3.1474
3
3.1589
2
3.0457
3
3.0470
3
3.1174
3
3.0608
3
3.0608
3
3.0256
3
3.0711
3
3.2021
2
ROHF                     2.6610
1
 
density functional LSDA 2.5052
1
2.9289
3
2.6996
1
2.7198
1
2.9245
3
2.9245
3
2.9568
3
2.8967
3
2.8967
3
2.8912
3
2.8998
3
2.7317
1
BLYP 2.9430
3
3.0166
3
3.0177
3
3.0481
3
3.0006
3
3.0006
3
3.0413
3
2.9853
3
2.9853
3
2.9749
3
2.9948
3
3.0843
3
B1B95 2.9081
3
2.7818
1
2.9913
3
3.0282
3
2.9769
3
2.9767
3
  2.9627
3
2.9632
3
2.9511
3
2.7159
1
3.0469
3
B3LYP 2.9147
3
3.0002
3
3.0091
3
3.0384
3
2.9867
3
2.9867
3
3.0303
3
2.9788
3
2.9788
3
2.9631
3
2.9884
3
3.0716
3
B3LYPultrafine   3.0012
3
    2.9880
3
2.9880
3
3.0302
3
2.9794
3
    2.9884
3
3.0700
3
B3PW91 2.9100
3
2.9971
3
3.0112
3
3.0371
3
2.9840
3
2.9840
3
3.0230
3
2.9709
3
2.9709
3
2.9554
3
2.9756
3
3.0634
3
mPW1PW91 2.9037
3
2.9919
3
3.0069
3
3.0356
3
2.9793
3
2.9793
3
3.0184
3
2.9671
3
2.9671
3
2.9508
3
2.9715
3
3.0567
3
M06-2X 2.8892
3
2.9823
3
2.9998
3
3.0159
3
2.9699
3
2.9699
3
3.0058
3
2.9637
3
2.9637
3
2.9488
3
2.9708
3
3.0375
3
PBEPBE 2.9277
3
2.9950
3
2.9960
3
3.0274
3
2.9831
3
2.9831
3
3.0190
3
2.9604
3
2.9604
3
2.9539
3
2.9657
3
3.0599
3
PBEPBEultrafine   2.9951
3
    2.9843
3
2.9843
3
3.0193
3
2.9613
3
    2.9657
3
3.0598
3
PBE1PBE 2.9020
3
2.8193
1
3.0002
3
3.0279
3
2.9760
3
2.9760
3
3.0149
3
2.9622
3
2.9622
3
2.9480
3
2.9675
3
3.0515
3
HSEh1PBE 2.9028
3
2.9867
3
3.0002
3
3.0272
3
2.9758
3
2.9758
3
3.0148
3
2.9627
3
2.9627
3
2.9481
3
2.9684
3
3.0518
3
TPSSh 2.9163
3
2.9981
3
3.0096
3
3.0367
3
2.9859
3
2.9859
3
3.0225
3
2.9686
3
2.9686
3
2.9557
3
2.9735
3
3.0614
3
wB97X-D 2.9041
3
3.0026
3
3.0269
3
3.0522
3
2.9917
3
2.9917
3
3.0390
3
2.9886
3
2.9886
3
2.9663
3
2.9974
3
3.0763
3
B97D3 2.9438
3
3.0309
3
3.0353
3
3.0602
3
3.0128
3
3.0128
3
3.0529
3
2.9957
3
2.9957
3
2.9830
3
3.0034
3
3.0947
3
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
Moller Plesset perturbation MP2 2.8898
3
3.0566
3
3.0574
3
3.0623
3
2.9950
3
2.9950
3
3.0405
3
2.9819
3
2.9819
3
2.9471
3
2.9876
3
3.1220
3
MP2=FULL 2.8992
3
3.0366
3
3.0338
3
3.0620
3
2.9935
3
2.9935
3
3.0385
3
2.9785
3
2.9785
3
2.9417
3
2.9813
3
3.0904
3
ROMP2 2.5101
1
  2.7996
1
2.7850
1
2.6939
1
2.6939
1
2.7608
1
2.6991
1
2.6991
1
2.6539
1
2.6026
1
2.8458
1
MP3         2.9957
3
  3.0417
3
      3.0009
3
3.1196
3
MP3=FULL   3.0385
3
3.0415
3
3.0776
3
2.9939
3
2.9939
3
3.0399
3
2.9854
3
2.9854
3
2.9467
3
2.9929
3
3.0899
3
MP4   3.0723
3
    2.9989
3
      2.9905
3
  2.9986
3
3.1300
3
MP4=FULL   3.0514
3
    2.9973
3
      2.9877
3
  2.9919
3
 
B2PLYP 2.5302
2
3.0168
3
3.0222
3
3.0424
3
2.9875
3
2.9875
3
3.0317
3
2.9776
3
2.9776
3
2.9559
3
2.9871
3
3.0837
3
B2PLYP=FULL 2.9067
3
3.0097
3
3.0140
3
3.0423
3
2.9870
3
2.9870
3
3.0312
3
2.9767
3
2.9767
3
2.9543
3
2.9857
3
3.0736
3
B2PLYP=FULLultrafine 2.9066
3
3.0099
3
3.0150
3
3.0423
3
2.9873
3
2.9873
3
3.0313
3
2.9774
3
2.9774
3
2.9540
3
2.9858
3
3.0734
3
Configuration interaction CID   3.0566
3
3.0636
3
3.0872
3
3.0016
3
    2.9996
3
    3.0124
3
 
CISD   3.0612
3
3.0719
3
3.0890
3
3.0025
3
    3.0006
3
    3.0130
3
 
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
Quadratic configuration interaction QCISD   3.0663
3
3.0745
3
3.0837
3
2.9998
3
2.9998
3
3.0466
3
2.9947
3
2.9947
3
2.9561
3
3.0052
3
3.1278
3
QCISD(T)         2.9987
3
    2.9911
3
    3.0002
3
3.1297
3
QCISD(T)=FULL         2.9972
3
  3.0438
3
      2.9934
3
 
QCISD(TQ)         2.9971
3
  3.0432
3
      3.1242
2
 
QCISD(TQ)=FULL         2.9956
3
  3.0416
3
         
Coupled Cluster CCD   3.0560
3
3.0627
3
3.0724
3
2.9967
3
2.9967
3
3.0432
3
2.9918
3
2.9918
3
2.9544
3
3.0025
3
3.1222
3
CCSD         2.9983
3
        2.9551
3
3.0035
3
3.1254
3
CCSD=FULL         2.9968
3
        2.9490
3
2.9974
3
3.0949
3
CCSD(T)         2.9983
3
2.9983
3
3.0450
3
2.9905
3
2.9908
3
2.9519
3
2.9997
3
3.1287
3
CCSD(T)=FULL         2.9967
3
          2.9930
3
3.0958
3
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

average calculated bond lengths (Å)
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD cc-pVTZ-PP aug-cc-pVTZ-PP Def2TZVPP
hartree fock HF 3.2386
2
  3.3982
3
  3.1802
2
3.1664
2
    2.6497
1
density functional B3LYP 3.1788
3
  3.1732
3
  3.0876
3
3.0593
3
    2.5879
1
PBEPBE                 2.5716
1
wB97X-D 3.4175
3
  3.1988
3
  3.1530
2
3.0792
3
     
Moller Plesset perturbation MP2 3.2966
2
  3.1789
3
  3.1123
3
3.0998
3
    2.6354
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.