return to home page

III.G.1.a.

Comparison of levels of theory for H-K


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 3.3166
1
PM6 3.5352
2
composite G2 2.9112
2
G3 3.5022
1
G3B3 2.8626
2
G4 2.2538
1
CBS-Q 3.5000
1

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 2.6444
1
2.8713
2
2.8217
2
2.9654
2
2.7148
3
2.8898
2
2.8880
2
2.9628
2
2.8952
2
2.8604
2
2.3077
1
3.0487
2
ROHF   3.3818
1
3.2908
1
3.5702
1
3.5000
1
3.4593
1
3.5000
1
3.6186
1
3.4840
1
    3.7110
1
density functional LSDA 2.2795
2
2.6585
2
2.6523
2
2.7160
2
2.6310
2
2.6204
2
2.6197
2
2.5760
2
2.5477
2
2.6092
2
  3.1724
1
SVWN   2.6916
2
    2.6308
2
2.9902
1
2.6196
2
2.9522
1
2.8964
1
2.9879
1
   
BLYP 2.5472
1
2.8051
2
2.7446
2
2.8497
2
2.7712
2
2.7578
2
2.7568
2
2.7728
2
2.7352
2
2.7309
2
  3.4534
1
B1B95 2.5725
1
    3.4876
1
2.2841
1
  3.4079
1
  3.4314
1
    3.5314
1
B3LYP 2.5390
1
2.7879
2
2.7302
2
2.8325
2
2.7567
2
2.7421
2
2.7410
2
2.7534
2
2.7122
2
2.7167
2
  2.8831
2
B3LYPultrafine         2.7495
2
             
B3PW91 2.5630
1
2.8424
2
2.7885
2
2.9176
2
2.8245
2
2.8095
2
2.8083
2
2.8478
2
2.7937
2
2.7757
2
  3.6297
1
mPW1PW91 2.5651
1
2.8096
2
2.7691
2
3.4217
1
2.8015
2
2.7891
2
2.7882
2
2.8056
2
2.7691
2
2.7608
2
  3.5547
1
M06-2X 2.5537
1
3.4706
1
3.4440
1
3.8188
1
3.0250
2
3.7584
1
3.7587
1
4.0838
1
4.0311
1
3.5000
1
  4.0897
1
PBEPBE 2.5537
1
2.7933
2
2.7479
2
2.8307
2
2.7657
2
2.7539
2
2.7530
2
2.7606
2
2.7292
2
2.7296
2
  3.4139
1
PBEPBEultrafine         2.2919
1
             
PBE1PBE 2.5558
1
3.1886
1
3.1886
1
3.3524
1
2.7741
2
3.2675
1
3.2434
1
3.3040
1
3.2374
1
3.2120
1
  3.4533
1
HSEh1PBE 2.5542
1
3.2571
1
3.1802
1
3.3491
1
2.7676
2
3.2319
1
3.2298
1
3.2972
1
3.2236
1
3.1993
1
  3.4553
1
TPSSh         2.8832
2
  2.8803
2
         
Moller Plesset perturbation MP2 2.6444
1
2.8821
2
2.8290
2
2.9691
2
2.8868
2
2.8531
2
2.8502
2
2.8814
2
2.7909
2
2.8071
2
  3.0438
2
MP2=FULL 2.6419
1
2.8794
2
2.8208
2
2.9690
2
2.8867
2
2.8530
2
2.8500
2
2.8809
2
2.7869
2
2.8066
2
  3.7012
1
ROMP2 2.6460
1
3.2910
1
3.2910
1
3.5602
1
3.4553
1
3.4099
1
3.4039
1
3.5000
1
3.3397
1
3.3330
1
  3.7112
1
MP3         2.8891
2
  2.8948
2
         
MP3=FULL         2.9087
2
  2.8947
2
         
MP4   2.8929
2
    2.8913
2
      3.3342
1
     
B2PLYP         2.2928
1
             
Configuration interaction CID   2.8935
2
2.8388
2
2.9777
2
2.8928
2
    2.8880
2
       
CISD   2.9004
2
2.8436
2
2.9847
2
2.8954
2
    2.8885
2
       
Quadratic configuration interaction QCISD   2.9004
2
2.8436
2
2.9845
2
2.8990
2
2.8599
2
2.8567
2
2.8960
2
3.3366
1
3.3299
1
  3.7110
1
QCISD(T)         2.8990
2
            3.7110
1
Coupled Cluster CCD   2.8935
2
2.8388
2
2.9778
2
2.8938
2
2.8552
2
2.8521
2
2.8910
2
3.3386
1
3.3305
1
  3.7110
1
CCSD         2.8993
2
             
CCSD(T)         2.8988
2
            3.7110
1
CCSD(T)=FULL         3.4499
1
            3.7009
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 2.8845
2
  3.1929
2
  2.8854
2
2.8549
2
density functional B1B95 2.3578
1
         
B3LYP 2.8616
2
  3.1466
2
  2.7742
2
2.7235
2
Moller Plesset perturbation MP2 2.8938
2
  3.1927
2
  2.8954
2
2.8596
2
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.