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III.G.1.a.

Comparison of levels of theory for Br-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 AM1 2.1404
2
PM3 2.3130
2
PM6 2.4314
3
composite G2 2.3328
3
G3B3 2.3765
3
G4 2.3560
3
CBS-Q 2.4185
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 2.4314
2
2.6417
3
2.3224
3
2.6355
3
2.3329
6
2.3328
3
2.3313
3
2.3402
3
2.3402
3
2.3026
3
2.1228
1
2.3356
3
2.3337
3
2.3128
3
2.1252
1
2.3354
3
2.3122
3
2.1251
1
ROHF         2.4288
2
                         
density functional LSDA 2.3633
3
2.3651
3
2.3040
3
2.4458
3
2.3226
3
2.3226
3
2.3182
3
2.3306
3
2.3306
3
2.2858
3
    2.3261
3
2.3001
3
  2.4391
2
2.6986
1
 
SVWN   2.4632
3
    2.3226
3
  2.3182
3
                     
BLYP 2.5181
2
2.5589
3
2.4029
3
2.5417
3
2.4299
3
2.4299
3
2.4248
3
2.4413
3
2.4413
3
2.3920
3
    2.4358
3
2.4135
3
  2.2226
1
   
B1B95 2.3700
3
2.3859
3
2.3251
3
2.4613
3
2.3423
3
2.3434
3
2.3406
3
2.3515
3
2.3515
3
2.3103
3
    2.3476
3
2.3234
3
  2.4784
2
2.4103
2
 
B3LYP 2.3912
3
2.5117
3
2.3589
3
2.4934
3
2.3802
3
2.3802
3
2.3770
3
2.3892
3
2.3892
3
2.3455
3
  2.3860
3
2.3840
3
2.3625
3
2.1660
1
2.3786
3
2.3582
3
2.1658
1
B3LYPultrafine         2.4778
2
                      2.3558
3
 
B3PW91 2.4603
2
2.4893
3
2.3336
3
2.4695
3
2.3517
3
2.3517
3
2.3480
3
2.3582
3
2.3582
3
2.3175
3
    2.3553
3
2.3309
3
  2.1681
1
   
mPW1PW91 2.3303
3
2.4776
3
2.3223
3
2.4577
3
2.3392
3
2.3392
3
2.3360
3
2.3458
3
2.3458
3
2.3059
3
    2.3427
3
2.3190
3
  2.1605
1
   
M06-2X         2.3249
3
                         
PBEPBE 2.4896
2
2.5175
3
2.3577
3
2.5000
3
2.3797
3
2.3797
3
2.3754
3
2.3887
3
2.3887
3
2.3425
3
2.1584
1
  2.3838
3
2.3586
3
  2.1869
1
2.1662
1
 
PBEPBEultrafine         2.1807
1
                         
PBE1PBE         2.3357
3
                         
HSEh1PBE         2.3412
3
                         
TPSSh         2.3557
3
  2.3524
3
            2.3363
3
       
Moller Plesset perturbation MP2 2.4172
2
2.4771
3
2.3017
3
2.4604
3
2.2814
4
2.3168
3
2.3172
3
2.3214
3
2.3214
3
2.2829
3
  2.3163
3
2.3226
3
2.2465
4
2.1244
1
2.3278
3
2.2812
3
 
MP2=FULL 2.4171
2
2.4771
3
2.3008
3
2.4602
3
2.2786
4
2.3140
3
2.3142
3
2.3187
3
2.3187
3
2.2737
3
    2.3216
3
2.2415
4
2.1211
1
2.1799
1
   
MP3         2.3280
3
  2.3234
3
                     
MP3=FULL         2.3210
3
  2.3226
3
                     
MP4   2.4909
3
    2.3345
3
      2.4186
2
        2.1559
1
       
B2PLYP         2.3560
3
                2.3292
3
       
Configuration interaction CID   2.4910
3
2.3113
3
2.4727
3
2.3260
3
    2.3302
3
2.1672
1
                 
CISD   2.6149
2
2.3155
3
2.6073
2
2.3308
3
    2.3350
3
2.1691
1
                 
Quadratic configuration interaction QCISD   2.5332
3
2.3320
3
2.5191
3
2.3485
3
2.3485
3
2.3497
3
2.3547
3
2.3547
3
2.3079
3
    2.3526
3
2.3119
3
       
QCISD(T)         2.3529
3
              2.4357
2
2.3949
2
  2.4463
2
2.7170
1
 
Coupled Cluster CCD   2.4932
3
2.3146
3
2.4764
3
2.3299
3
2.3299
3
2.3313
3
2.3351
3
2.3351
3
2.2968
3
    2.3362
3
2.3768
2
  2.4193
2
2.3732
2
 
CCSD         2.3460
3
                         
CCSD(T)         2.1888
1
          2.1546
1
  2.3553
3
2.3149
3
  2.3638
3
2.3143
3
 
CCSD(T)=FULL         2.4304
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 2.5591
2
  2.5572
2
  2.7206
3
2.6325
3
density functional B1B95 2.3030
1
         
B3LYP 2.4983
3
  2.4982
3
  2.5242
3
2.5051
3
Moller Plesset perturbation MP2 2.4617
3
  2.4607
3
  2.4715
3
2.4624
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.