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III.G.1.a.

Comparison of levels of theory for K-H


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 PM6 1.6451
1
composite G2 2.3223
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   2.3608
1
2.3527
1
2.3605
1
2.3223
1
2.3203
1
2.3204
1
2.3067
1
2.3069
1
2.3127
1
2.3077
1
2.3864
1
density functional LSDA 2.0945
1
2.2973
1
2.2848
1
2.2938
1
2.2535
1
2.2505
1
2.2505
1
2.1999
1
2.1990
1
2.2306
1
   
SVWN   2.2972
1
    2.2531
1
  2.2502
1
         
BLYP   2.3423
1
2.3240
1
2.3358
1
2.2995
1
2.2965
1
2.2965
1
2.2525
1
2.2519
1
2.2754
1
   
B1B95         2.2841
1
             
B3LYP   2.3271
1
2.3134
1
2.3223
1
2.2852
1
2.2827
1
2.2827
1
2.2440
1
2.2438
1
2.2637
1
  2.3368
1
B3LYPultrafine         2.2848
1
             
B3PW91   2.3333
1
2.3202
1
2.3256
1
2.2849
1
2.2824
1
2.2825
1
2.2411
1
2.2406
1
2.2637
1
   
mPW1PW91   2.3267
1
2.3162
1
  2.2803
1
2.2779
1
2.2779
1
2.2389
1
2.2384
1
2.2606
1
   
M06-2X         2.2756
1
             
PBEPBE   2.3386
1
2.3223
1
2.3319
1
2.2925
1
2.2895
1
2.2895
1
2.2433
1
2.2422
1
2.2696
1
   
PBEPBEultrafine         2.2919
1
             
HSEh1PBE         2.2800
1
             
Moller Plesset perturbation MP2FC   2.3824
1
2.3671
1
2.3779
1
2.3178
1
2.2961
1
2.2964
1
2.2628
1
2.2432
1
2.2823
1
  2.3765
1
MP2FU   2.3817
1
2.3636
1
2.3779
1
2.3178
1
2.2961
1
2.2964
1
2.2619
1
2.2412
1
2.2822
1
   
MP3         2.3262
1
             
MP4   2.4033
1
    2.3323
1
             
B2PLYP         2.2928
1
  2.2845
1
         
Configuration interaction CID   2.4051
1
2.3867
1
2.3958
1
2.3343
1
    2.2760
1
       
CISD   2.4190
1
2.3963
1
2.4093
1
2.3420
1
    2.2770
1
       
Quadratic configuration interaction QCISD   2.4190
1
2.3963
1
2.4095
1
2.3469
1
2.3161
1
2.3165
1
2.2920
1
       
QCISD(T)         2.3473
1
             
Coupled Cluster CCD   2.4051
1
2.3867
1
2.3959
1
2.3362
1
2.3064
1
2.3068
1
2.2820
1
       
CCSD         2.3475
1
             
CCSD(T)         2.3475
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 2.3465
1
  2.4595
1
  2.3533
1
2.3460
1
density functional B1B95 2.3578
1
         
B3LYP 2.3561
1
  2.4448
1
  2.3200
1
2.3091
1
Moller Plesset perturbation MP2FC 2.3650
1
  2.4590
1
  2.3733
1
2.3553
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.