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III.G.1.a.

Comparison of levels of theory for As-As


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 2.3922
6
PM6 2.4296
7
composite G2 2.3456
7
G3 2.3685
7
G3B3 2.4144
7
G4 2.1154
1
CBS-Q 2.3480
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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF 2.3084
7
2.5182
7
2.3609
7
2.4760
7
2.3499
7
2.3499
7
2.3544
7
2.3724
7
2.3724
7
2.3144
7
2.3710
7
2.3723
7
2.3667
7
2.4160
6
2.3763
7
2.3670
7
2.4160
6
density functional LSDA 2.3085
7
2.3620
7
2.3620
7
2.4706
7
2.3580
7
2.3580
7
2.3632
7
2.3781
7
2.3781
7
2.3148
7
2.4242
6
2.3832
7
2.3701
7
  2.3841
7
2.3702
7
 
SVWN   2.5591
6
    2.4037
6
2.4037
6
2.4088
6
2.4249
6
2.4249
6
2.3575
6
  2.4305
6
2.4167
6
  2.4314
6
2.4169
6
 
BLYP 2.3463
7
2.5590
7
2.4212
7
2.5356
7
2.4229
7
2.4229
7
2.4283
7
2.4469
7
2.4469
7
2.3697
7
2.4974
6
2.4506
7
2.4388
7
       
B1B95 2.3160
7
2.3613
7
2.3613
7
2.4725
7
2.3514
7
2.3514
7
2.3561
7
2.3759
7
2.3759
7
2.3128
7
2.4231
6
2.3757
7
2.3694
7
  2.3780
7
2.3699
7
 
B3LYP 2.3335
7
2.5346
7
2.3933
7
2.5065
7
2.3903
7
2.3903
7
2.3954
7
2.4128
7
2.4128
7
2.3437
7
2.4119
7
2.4159
7
2.4053
7
2.4536
6
2.4176
7
2.4056
7
2.4534
6
B3LYPultrafine         2.3904
7
            2.4666
6
2.4553
6
  2.4683
6
2.4068
7
 
B3PW91 2.3271
7
2.5235
7
2.3785
7
2.4893
7
2.3705
7
2.3705
7
2.3750
7
2.3928
7
2.3928
7
2.3281
7
2.4408
6
2.3950
7
2.3858
7
       
mPW1PW91 2.3235
7
2.5189
7
2.3731
7
2.4831
7
2.3637
7
2.3637
7
2.3683
7
2.3859
7
2.3859
7
2.3228
7
2.4338
6
2.3877
7
2.3793
7
  2.3899
7
2.3796
7
 
M06-2X 2.3652
6
2.5867
6
2.4248
6
2.5396
6
2.4020
6
2.4020
6
2.4062
6
2.4294
6
2.4294
6
2.3655
6
2.4350
6
2.4279
6
2.4290
6
  2.4316
6
2.4295
6
 
PBEPBE 2.3318
7
2.5418
7
2.3980
7
2.5111
7
2.3913
7
2.3913
7
2.3961
7
2.4155
7
2.4155
7
2.3448
7
2.4638
6
2.4174
7
2.4085
7
  2.4191
7
2.4090
7
 
PBEPBEultrafine         2.4382
6
            2.4661
6
2.4567
6
  2.4679
6
2.4573
6
 
PBE1PBE 2.3756
6
2.4183
6
2.4183
6
2.5445
6
2.3621
7
2.4091
6
2.4135
6
2.4330
6
2.4330
6
2.3655
6
2.4324
6
2.4348
6
2.4264
6
  2.4372
6
2.4269
6
 
HSEh1PBE 2.3761
6
2.5819
6
2.4199
6
2.5495
6
2.4125
6
2.4125
6
2.4171
6
2.4367
6
2.4367
6
2.3682
6
2.4361
6
2.4388
6
2.4302
6
  2.4410
6
2.4305
6
 
TPSSh         2.3682
7
  2.3726
7
          2.3840
7
       
Moller Plesset perturbation MP2 2.3788
7
2.6100
7
2.4010
7
2.5709
7
2.4050
7
2.4050
7
2.4101
7
2.4287
7
2.4287
7
2.3472
7
2.4058
7
2.4146
7
2.3872
7
2.4125
6
2.4271
7
2.3877
7
2.4082
6
MP2=FULL 2.3782
7
2.6100
7
2.3978
7
2.5703
7
2.3915
7
2.3915
7
2.3967
7
2.4159
7
2.4159
7
2.3198
7
2.4478
6
2.4113
7
2.3742
7
2.4078
6
2.4247
7
2.3654
7
2.3985
6
MP3         2.3984
7
  2.3980
7
                   
MP3=FULL         2.3874
7
  2.3919
7
                   
MP4   2.6030
7
    2.4141
7
      2.4385
7
  2.4659
6
2.4728
6
2.3990
7
       
MP4=FULL   2.6621
6
    2.4444
6
      2.4742
6
    2.4689
6
2.4293
6
       
B2PLYP                         2.1221
1
       
Configuration interaction CID   2.5589
7
2.3759
7
2.5195
7
2.3752
7
    2.3947
7
                 
CISD   2.5603
7
2.3766
7
2.5211
7
2.3761
7
    2.3957
7
                 
Quadratic configuration interaction QCISD   2.5929
7
2.3974
7
2.5542
7
2.3988
7
2.3988
7
2.4031
7
2.4203
7
2.4203
7
2.3407
7
2.4520
6
2.4120
7
2.3817
7
  2.4189
7
2.3806
7
 
QCISD(T)         2.4118
7
          2.4657
6
2.4255
7
2.3954
7
  2.4825
6
2.4417
6
 
Coupled Cluster CCD   2.5885
7
2.3943
7
2.5495
7
2.3956
7
2.3956
7
2.4000
7
2.4166
7
2.4166
7
2.3380
7
2.4483
6
2.4083
7
2.3782
7
  2.4157
7
2.3777
7
 
CCSD         2.3980
7
          2.4515
6
2.4113
7
2.3813
7
  2.4672
6
2.4276
6
 
CCSD=FULL         2.4325
6
          2.4501
6
2.4564
6
2.4168
6
       
CCSD(T)         2.4112
7
          2.4652
6
2.4249
7
2.3952
7
  2.4338
7
2.3949
7
 
CCSD(T)=FULL         2.3989
7
          2.4639
6
2.4216
7
2.3837
7
  2.4316
7
2.1050
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 2.4573
7
  2.4573
7
  2.5158
7
2.4601
7
density functional B3LYP 2.5086
7
  2.5086
7
  2.5617
7
2.5054
7
Moller Plesset perturbation MP2 2.5763
7
  2.5763
7
  2.6294
7
2.5696
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.