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III.G.1.a.

Comparison of levels of theory for Na-Cl


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 2.5499
7
composite G2 2.5910
7
G3 2.5910
7
G3B3 2.5693
7
G4 2.5738
7
CBS-Q 2.5910
7

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
hartree fock HF 2.4043
7
2.6230
7
2.5880
7
2.6390
7
2.5803
18
2.5910
7
2.5721
7
2.5888
7
2.5887
7
2.5764
7
2.5295
5
2.6506
3
2.6022
7
2.7017
2
2.5930
3
2.7093
2
2.5832
7
2.5920
3
2.5995
3
density functional LSDA 2.3424
7
2.5304
7
2.5032
7
2.5503
7
2.5092
7
2.5092
7
2.5151
7
2.5069
7
2.5069
7
2.4833
7
    2.5206
7
2.5052
7
2.4586
1
2.5069
7
2.4653
1
2.5761
2
 
SVWN   2.5438
7
    2.4693
6
  2.5151
7
                       
BLYP 2.3952
7
2.5942
7
2.5589
7
2.6164
7
2.5765
7
2.5765
7
2.5874
7
2.5852
7
2.5851
7
2.5577
7
    2.7004
2
2.6878
2
  2.5375
5
     
B1B95 2.3895
7
2.5751
7
2.5476
7
2.6150
7
2.5560
7
2.5562
7
2.5634
7
2.5168
6
2.5168
6
2.4973
6
    2.5710
7
2.5569
7
  2.5948
4
     
B3LYP 2.3866
7
2.5823
7
2.5461
7
2.6025
7
2.5633
7
2.5609
7
2.5695
7
2.5663
7
2.6802
2
2.5431
7
2.5092
5
2.5832
7
2.5694
7
2.6690
2
2.5641
3
2.6758
2
2.5598
7
2.5607
3
2.5723
3
B3LYPultrafine         2.5635
7
                2.5430
4
    2.5807
7
   
B3PW91 2.5869
2
2.6089
7
2.5738
7
2.6174
7
2.5713
7
2.5713
7
2.5766
7
2.5722
7
2.6940
2
2.5525
7
    2.7199
2
2.6864
2
  2.5243
5
     
mPW1PW91 2.5803
2
2.5952
7
2.6882
2
2.6082
7
2.5622
7
2.5622
7
2.5677
7
2.5619
7
2.5619
7
2.5445
7
    2.7050
2
2.6722
2
  2.5175
5
     
M06-2X         2.8286
7
                           
PBEPBE 2.5698
2
2.5929
7
2.6776
2
2.7506
2
2.5664
7
2.5664
7
2.5745
7
2.5691
7
2.5696
7
2.5470
7
2.5128
5
  2.5759
7
2.5655
7
2.6594
2
    2.6543
2
 
PBEPBEultrafine         2.5313
9
                           
PBE1PBE         2.5559
7
                           
HSEh1PBE         2.5563
7
                           
TPSSh         2.8088
7
  2.8111
7
            2.8090
7
         
Moller Plesset perturbation MP2 2.6033
2
2.6378
7
2.5726
7
2.6520
7
2.5381
8
2.5656
7
2.5567
15
2.5537
7
2.5541
7
2.6066
6
  2.6117
7
2.6018
7
2.6010
3
2.5989
3
2.6272
3
2.6093
3
2.4075
1
2.6020
3
MP2=FULL 2.5993
2
2.6382
7
2.6853
2
2.8134
2
2.5432
8
2.5628
7
2.5623
7
2.5443
7
2.6500
2
2.6606
2
    2.7281
2
2.5784
3
2.5642
3
2.5465
5
    2.5785
3
MP3         2.5627
7
  2.8109
7
                       
MP3=FULL         2.8091
7
  2.8091
7
                       
MP4   2.7865
2
    2.8635
7
    2.3863
1
2.6550
2
        2.4055
1
         
B2PLYP         2.5557
7
                2.8090
7
         
B2PLYP=FULLultrafine         2.5430
4
                           
Configuration interaction CID   2.7862
2
2.6884
2
2.8146
2
2.5667
7
    2.5671
3
                     
CISD   2.7863
2
2.6890
2
2.8148
2
2.5658
7
    2.6592
2
                     
Quadratic configuration interaction QCISD   2.6398
7
2.6873
2
2.8157
2
2.5663
7
2.6709
2
2.5800
3
2.5528
7
2.5662
3
2.6861
2
    2.6215
3
2.5999
3
         
QCISD(T)         2.5785
3
    2.3869
1
        2.7302
2
2.6978
2
  2.7292
2
2.7063
2
   
Coupled Cluster CCD   2.7868
2
2.6865
2
2.8153
2
2.5651
7
2.6704
2
2.6667
2
2.5651
3
2.6556
2
2.6860
2
    2.6207
3
2.6978
2
  2.7269
2
2.7032
2
   
CCSD         2.8641
7
    2.3859
1
                     
CCSD(T)         2.3956
1
2.3956
1
  2.3868
1
    2.4011
1
  2.6211
3
2.6002
3
2.8597
1
2.6285
3
2.6084
3
   
CCSD(T)=FULL         2.6662
2
                  2.7829
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 2.7139
7
2.6476
7
2.6429
7
2.5856
7
2.6341
7
2.6138
7
density functional B1B95 2.5028
1
2.5876
5
       
B3LYP 2.7079
7
2.6481
7
2.6498
7
2.5959
7
2.6366
7
2.5832
7
Moller Plesset perturbation MP2 2.7249
7
2.6347
7
2.6590
7
2.5705
7
2.6355
7
2.6235
7
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.