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III.G.1.a.

Comparison of levels of theory for Br-Br


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 2.2282
2
PM3 2.4801
3
PM6 2.3821
3
composite G2 2.4555
3
G3B3 2.5109
3
G4 2.4989
3
CBS-Q 2.5345
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 cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF 2.5019
2
2.5846
3
2.4291
3
2.5618
3
2.4555
6
2.4555
3
2.4578
3
2.4672
3
2.5564
2
2.4320
3
2.2722
1
2.4702
3
2.4683
3
2.4525
3
2.2726
1
2.4729
3
2.4514
3
2.2726
1
ROHF         2.8912
1
                         
density functional LSDA 2.4732
3
2.4664
3
2.4045
3
2.5663
3
2.4429
3
2.4429
3
2.4396
3
2.5797
2
2.5797
2
2.4144
3
    2.4602
3
2.4351
3
  2.4539
3
2.5097
2
 
SVWN   2.5860
3
    2.5601
2
  2.4398
3
                     
BLYP 2.6258
2
2.6931
3
2.5067
3
2.6622
3
2.5559
3
2.5559
3
2.6894
2
2.5761
3
2.6798
2
2.5185
3
    2.7270
2
2.5560
3
       
B1B95 2.4785
3
2.4941
3
2.4329
3
2.5847
3
2.4661
3
2.4672
3
2.4660
3
2.4820
3
2.4820
3
2.4401
3
    2.4855
3
2.4624
3
  2.4813
3
2.5484
2
 
B3LYP 2.5012
3
2.6411
3
2.4678
3
2.6173
3
2.5076
3
2.5076
3
2.5055
3
2.5228
3
2.6174
2
2.4765
3
  2.5245
3
2.5246
3
2.5045
3
2.3129
1
2.5211
3
2.5009
3
2.3130
1
B3LYPultrafine         2.6012
2
                      2.4970
3
 
B3PW91 2.5700
2
2.6167
3
2.4411
3
2.5931
3
2.4765
3
2.4765
3
2.4744
3
2.4890
3
2.5795
2
2.4487
3
    2.4931
3
2.4704
3
       
mPW1PW91 2.4440
3
2.6044
3
2.4306
3
2.5819
3
2.4643
3
2.4643
3
2.4629
3
2.4766
3
2.5650
2
2.4378
3
    2.4804
3
2.4584
3
       
M06-2X         2.4498
3
                         
PBEPBE 2.5967
2
2.6447
3
2.4614
3
2.6212
3
2.6339
2
2.6339
2
2.4983
3
2.6555
2
2.9815
1
2.4716
3
    2.5211
3
2.4974
3
  2.3302
1
2.3114
1
 
PBEPBEultrafine         2.3146
1
                         
PBE1PBE         2.4606
3
                         
HSEh1PBE         2.4673
3
                         
TPSSh         2.4811
3
  2.4792
3
            2.4744
3
       
Moller Plesset perturbation MP2 2.5342
2
2.6430
3
2.4355
3
2.6297
3
2.4717
3
2.4717
3
2.4738
3
2.4728
3
2.5552
2
2.4301
3
  2.4706
3
2.4788
3
2.2768
1
2.2613
1
2.4852
3
2.2787
1
2.2611
1
MP2=FULL 2.5342
2
2.6431
3
2.4338
3
2.6294
3
2.4648
3
2.4648
3
2.4667
3
2.4681
3
2.5503
2
2.4177
3
    2.4773
3
2.2326
2
2.2571
1
2.3241
1
   
MP3         2.4837
3
  2.4890
3
                     
MP3=FULL         2.4824
3
  2.4860
3
                     
MP4   2.6531
3
    2.4864
3
      2.5742
2
        2.4534
3
       
B2PLYP         2.4874
3
                2.4722
3
       
Configuration interaction CID   2.6381
3
2.4373
3
2.6232
3
2.4726
3
    2.4744
3
                   
CISD   2.6415
3
2.4381
3
2.6271
3
2.4735
3
    2.4764
3
                   
Quadratic configuration interaction QCISD   2.6498
3
2.4457
3
2.6367
3
2.4825
3
2.4825
3
2.4867
3
2.4864
3
2.5677
2
2.4438
3
    2.4902
3
2.4493
3
       
QCISD(T)         2.4876
3
              2.5747
2
2.2133
1
  2.5865
2
2.5293
2
 
Coupled Cluster CCD   2.6457
3
2.4441
3
2.6318
3
2.4807
3
2.4807
3
2.4846
3
2.4828
3
2.5639
2
2.4415
3
    2.4877
3
2.1952
1
  2.5761
2
2.5202
2
 
CCSD         2.4824
3
                         
CCSD(T)         2.3340
1
              2.4968
3
2.2574
2
  2.5072
3
2.4539
3
 
CCSD(T)=FULL         2.5567
2
                         

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 2.5564
3
  2.5564
3
  2.6058
3
2.5624
3
density functional B1B95 2.4281
1
         
B3LYP 2.6218
3
  2.6218
3
  2.6733
3
2.6257
3
Moller Plesset perturbation MP2 2.6359
3
  2.6359
3
  2.6759
3
2.6357
3
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.