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III.G.1.a.

Comparison of levels of theory for O-Si


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 1.5760
2
PM3 1.4830
5
PM6 1.2516
5
composite G2 1.5100
5
G3 1.5100
5
G3B3 1.5368
5
G4 1.5219
5
CBS-Q 1.5104
5

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 cc-pCVDZ cc-pCVTZ
hartree fock HF 1.5303
5
1.5915
5
1.5194
5
1.6160
5
1.5100
10
1.5100
5
1.5115
5
1.5043
5
1.5042
5
1.5008
5
1.4748
3
1.5158
5
1.5327
5
1.5069
5
1.5008
5
1.5337
5
1.5047
5
1.5140
3
1.4753
3
1.5033
1
1.4784
1
density functional LSDA 1.5747
5
1.5751
5
1.5457
5
1.6104
5
1.5368
5
1.5368
5
1.5378
5
1.5310
5
1.5310
5
1.5232
5
    1.5569
5
1.5303
5
1.5376
2
1.5566
5
1.5394
2
1.5105
1
     
SVWN   1.5953
5
    1.5248
4
  1.5378
5
                           
BLYP 1.5922
5
1.6138
5
1.5643
5
1.6312
5
1.5558
5
1.5558
5
1.5572
5
1.5508
5
1.5508
5
1.5422
5
    1.5756
5
1.5497
5
  1.5633
3
         
B1B95 1.5653
5
1.5702
5
1.5415
5
1.6069
5
1.5300
5
1.5315
5
1.5327
5
1.5261
5
1.5261
5
1.5203
5
    1.5526
5
1.5255
5
1.5391
2
1.5498
4
1.5568
1
1.5319
2
     
B3LYP 1.5714
5
1.5954
5
1.5461
5
1.6127
5
1.5368
5
1.5368
5
1.5386
5
1.5318
5
1.5552
2
1.5246
5
1.5099
3
1.5417
5
1.5572
5
1.5318
5
1.5342
3
1.5574
5
1.5293
5
1.5299
3
1.5095
3
1.5378
1
1.5121
1
B3LYPultrafine         1.5368
5
                      1.5254
5
       
B3PW91 1.5865
2
1.5941
5
1.5447
5
1.6103
5
1.5344
5
1.5344
5
1.5354
5
1.5291
5
1.5513
2
1.5229
5
    1.5552
5
1.5293
5
  1.5415
3
         
mPW1PW91 1.5824
2
1.5905
5
1.5655
2
1.6070
5
1.5308
5
1.5308
5
1.5320
5
1.5254
5
1.5254
5
1.5196
5
    1.5518
5
1.5259
5
  1.5378
3
         
M06-2X         1.5242
5
                               
PBEPBE 1.6041
2
1.6119
5
1.5837
2
1.6544
2
1.5524
5
1.5524
5
1.5533
5
1.5469
5
1.5469
5
1.5398
5
1.5267
3
  1.5731
5
1.5464
5
1.5558
2
  1.5345
3
1.5486
2
1.5270
1
   
PBEPBEultrafine         1.5389
3
                               
PBE1PBE         1.5316
5
                               
HSEh1PBE         1.5320
5
                               
TPSSh         1.5325
5
  1.5329
5
            1.5281
5
             
Moller Plesset perturbation MP2 1.5907
2
1.5823
5
1.5476
4
1.6094
5
1.5455
6
1.5487
5
1.5526
5
1.5385
5
1.5385
5
1.5376
5
  1.5545
5
1.5715
4
1.5399
6
1.5451
3
1.5778
5
1.5516
3
1.5427
3
1.5238
3
1.5591
1
1.5275
1
MP2=FULL 1.5911
2
1.5825
5
1.5603
2
1.6063
2
1.5451
6
1.5483
5
1.5520
5
1.5380
5
1.5581
2
1.5520
2
    1.5708
5
1.5462
3
1.5385
3
1.5648
3
  1.5400
2
1.5193
3
1.5588
1
1.5243
1
MP3         1.5290
5
  1.5231
5
                           
MP3=FULL         1.5230
5
  1.5242
5
                           
MP4   1.5692
2
    1.5644
5
    1.5574
1
1.5706
2
        1.5550
5
             
B2PLYP         1.5408
5
                1.5278
5
             
Configuration interaction CID   1.6161
2
1.5580
1
1.5626
1
1.5276
5
    1.5325
3
                         
CISD   1.6221
2
1.5581
1
1.6346
2
1.5296
5
    1.5486
2
                         
Quadratic configuration interaction QCISD   1.6129
5
1.5813
2
1.6657
2
1.5436
5
1.5705
2
1.5454
5
1.5317
5
1.5317
5
1.5544
2
    1.5666
5
1.5333
5
        1.5136
1
   
QCISD(T)         1.5492
5
    1.5278
1
        1.6010
2
1.5625
2
  1.5995
2
1.5587
2
       
Coupled Cluster CCD   1.6091
2
1.5584
1
1.6055
2
1.5344
5
1.5632
2
1.5619
2
1.5371
3
1.5513
2
1.5501
2
    1.5556
5
1.5540
2
  1.5898
2
1.5505
2
    1.5338
1
1.5048
1
CCSD         1.5370
5
    1.5136
1
                         
CCSD(T)   1.5966
1
    1.5301
3
1.5301
3
1.5393
1
1.5250
1
1.5250
1
  1.5199
1
  1.5974
2
1.5382
5
  1.5967
2
1.5563
2
  1.5189
1
1.5532
1
1.5201
1
CCSD(T)=FULL         1.5590
3
              1.5555
1
1.5243
1
          1.5528
1
1.5173
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 1.6100
5
1.5161
5
1.6108
5
1.5172
5
1.5822
5
1.6012
5
density functional B1B95 1.5859
3
1.5252
3
       
B3LYP 1.6100
5
1.5429
5
1.6103
5
1.5444
5
1.5846
5
1.6012
5
Moller Plesset perturbation MP2 1.6163
5
1.5556
5
1.6200
4
1.5570
5
1.5924
5
1.6077
5
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.