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Comparison of levels of theory for Mg-Be


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 2.4055
1
PM3 1.9273
1
PM6 3.3790
1
composite G2 3.3421
1
G3 3.3421
1
G3B3 3.1924
1
G4 3.1865
1
CBS-Q 3.3412
1

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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF 2.4801
1
5.0984
1
4.9967
1
5.2151
1
1.8588
1
5.1415
1
6.3092
1
7.0783
1
7.0783
1
4.9204
1
  5.3093
1
3.3402
1
7.0798
1
7.0769
1
7.0763
1
7.0774
1
7.0766
1
7.0761
1
density functional LSDA 2.4252
1
2.8556
1
2.8556
1
2.9187
1
2.8857
1
2.8857
1
2.8822
1
2.8725
1
2.8725
1
2.8708
1
  2.8867
1
  2.8884
1
2.8693
1
  2.8872
1
2.8686
1
 
BLYP 2.4704
1
3.0786
1
3.0227
1
3.1273
1
3.0692
1
3.0692
1
3.0602
1
3.0499
1
3.0499
1
3.0500
1
  3.0969
1
  3.0742
1
3.0493
1
  3.0645
1
3.0465
1
 
B1B95 2.4538
1
  3.1022
1
3.1868
1
3.1138
1
3.1138
1
3.1019
1
3.1102
1
3.1102
1
3.0924
1
  3.1483
1
  3.1103
1
3.1121
1
  3.1062
1
3.1104
1
 
B3LYP 2.4621
1
3.2064
1
3.1217
1
3.2519
1
3.1594
1
3.1594
1
3.1430
1
3.1377
1
3.1377
1
3.1314
1
  3.2303
1
3.1905
1
3.1590
1
2.8218
1
3.1265
1
3.1479
1
3.1352
1
3.1261
1
B3LYPultrafine   3.2084
1
    3.1614
1
3.1614
1
3.1453
1
3.1400
1
      3.2302
1
  3.1609
1
3.1396
1
  3.1499
1
3.1378
1
 
B3PW91 2.4516
1
3.0900
1
3.0327
1
3.1158
1
3.0623
1
3.0623
1
3.0525
1
3.0505
1
3.0505
1
3.0488
1
  3.0733
1
  3.0546
1
3.0461
1
  3.0548
1
3.0469
1
 
mPW1PW91 2.4480
1
3.1018
1
3.0424
1
3.1254
1
3.0695
1
3.0695
1
3.0590
1
3.0589
1
3.0589
1
3.0552
1
  3.0837
1
  3.0618
1
3.0553
1
  3.0615
1
3.0554
1
 
M06-2X 2.4498
1
3.3365
1
3.3091
1
3.3592
1
3.3212
1
3.3212
1
3.3131
1
3.3147
1
3.3147
1
3.2781
1
  3.4236
1
  3.3334
1
3.3337
1
  3.3219
1
3.3322
1
 
PBEPBE 2.4505
1
2.9722
1
2.9330
1
3.0035
1
2.9675
1
2.9675
1
2.9625
1
2.9572
1
2.9572
1
2.9564
1
  2.9708
1
3.1236
1
2.9658
1
2.9549
1
  2.9639
1
2.9540
1
 
PBEPBEultrafine   2.9708
1
    2.9666
1
2.9666
1
2.9613
1
2.9561
1
      2.9700
1
  2.9642
1
2.9536
1
  2.9623
1
2.9528
1
 
PBE1PBE 2.4454
1
  3.0300
1
3.1117
1
3.0583
1
3.0583
1
3.0485
1
3.0478
1
3.0478
1
3.0435
1
  3.0708
1
  3.0517
1
3.0453
1
  3.0510
1
3.0457
1
 
HSEh1PBE 2.4489
1
3.0775
1
3.0210
1
3.1025
1
3.0493
1
3.0493
1
3.0397
1
3.0384
1
3.0384
1
3.0343
1
  3.0618
1
  3.0435
1
3.0352
1
  3.0424
1
3.0350
1
 
TPSSh   3.0801
1
3.0232
1
3.0808
1
3.0246
1
3.0246
1
3.0160
1
3.0153
1
      3.0310
1
  3.0165
1
3.0071
1
  3.0181
1
3.0080
1
 
wB97X-D 2.4624
1
3.6530
1
3.4291
1
3.5687
1
3.4250
1
3.4250
1
3.4018
1
3.3910
1
3.3910
1
3.3367
1
  4.0279
1
  3.3981
1
3.3848
1
3.3705
1
3.3815
1
3.3828
1
3.3690
1
B97D3                     3.1646
1
               
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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
Moller Plesset perturbation MP2 2.4684
1
4.6630
1
4.4259
1
4.6504
1
4.1677
1
4.1677
1
4.3482
1
4.1071
1
4.1071
1
3.5275
1
  4.7013
1
3.2586
1
4.3417
1
3.6284
1
3.5639
1
3.9766
1
3.6322
1
3.5632
1
MP2=FULL 2.4607
1
4.6527
1
4.4028
1
4.6453
1
4.1341
1
4.1341
1
4.2678
1
4.0146
1
4.0146
1
3.2385
1
  4.6604
1
  4.3075
1
3.3305
1
3.4629
1
3.8385
1
3.2183
1
3.4197
1
MP3         4.1595
1
  4.2349
1
        4.5689
1
  4.1130
1
3.4827
1
       
MP3=FULL   4.6839
1
4.4125
1
4.7170
1
4.1339
1
4.1339
1
4.1658
1
3.7882
1
3.7882
1
3.1754
1
  4.5345
1
  4.0505
1
3.2000
1
  3.6440
1
3.1060
1
 
MP4   4.7905
1
    4.3150
1
      3.8527
1
    4.5543
1
  4.2304
1
3.3851
1
  3.6988
1
3.3935
1
 
MP4=FULL   4.7772
1
    4.2912
1
      3.7392
1
        4.1789
1
3.0990
1
  3.5571
1
3.0247
1
 
B2PLYP 2.4586
1
4.0506
1
3.6043
1
3.9407
1
3.3743
1
3.3743
1
3.3441
1
3.3259
1
3.3259
1
3.2634
1
  4.4441
1
  3.3512
1
3.2883
1
  3.3321
1
3.2881
1
 
B2PLYP=FULL 2.4563
1
4.0450
1
3.5990
1
3.9343
1
3.3594
1
3.3594
1
3.3290
1
3.3177
1
3.3177
1
3.1925
1
  4.4267
1
  3.3323
1
3.2213
1
  3.3100
1
3.2000
1
 
B2PLYP=FULLultrafine 2.4563
1
4.0263
1
3.5956
1
3.9288
1
3.3593
1
3.3593
1
3.3279
1
3.3166
1
3.3166
1
3.1934
1
  4.4394
1
  3.3313
1
3.2212
1
  3.3088
1
3.2000
1
 
Configuration interaction CID   4.9151
1
4.7142
1
5.1018
1
4.7324
1
    4.8461
1
                     
CISD   4.8995
1
4.7119
1
5.0756
1
4.7446
1
    4.9103
1
                     
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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
Quadratic configuration interaction QCISD   4.9816
1
4.8133
1
5.2221
1
4.9580
1
4.9580
1
5.2271
1
5.1891
1
5.1891
1
4.2027
1
  4.6590
1
  5.2113
1
4.6495
1
  4.8009
1
4.5007
1
 
QCISD(T)         4.6708
1
    4.6524
1
      4.6031
1
  4.7834
1
3.5160
1
  4.1918
1
3.5167
1
 
QCISD(T)=FULL         4.6333
1
  4.7412
1
            4.7519
1
3.0952
1
3.3546
1
4.0445
1
3.0100
1
3.3017
1
QCISD(TQ)         4.5513
1
  4.6797
1
            4.5888
1
3.3626
1
3.3115
1
3.8966
1
3.3677
1
3.3129
1
QCISD(TQ)=FULL         4.5216
1
  4.5997
1
            4.5665
1
3.0405
1
3.2849
1
3.6722
1
2.9724
1
 
Coupled Cluster CCD   5.0092
1
4.8321
1
5.2725
1
4.9706
1
4.9706
1
5.1289
1
5.1569
1
5.1569
1
4.1385
1
  4.6241
1
  5.1857
1
4.5115
1
  4.7127
1
4.3821
1
 
CCSD         4.9441
1
        4.2053
1
  4.6565
1
  5.2084
1
4.6490
1
4.4436
1
4.7996
1
4.5043
1
4.4208
1
CCSD=FULL         4.8902
1
        3.5514
1
  4.6353
1
  5.1420
1
3.9282
1
4.0198
1
4.7387
1
3.4856
1
3.9474
1
CCSD(T)         4.6659
1
4.6659
1
  4.6458
1
      4.6021
1
  4.7770
1
3.5347
1
3.4321
1
4.1914
1
3.5349
1
3.4310
1
CCSD(T)=FULL         4.6289
1
            4.5726
1
  4.7461
1
3.1117
1
3.3670
1
4.0476
1
3.0222
1
3.3140
1
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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ

average calculated bond lengths (Å)
Methods with effective core potentials (select basis sets)
daug-cc-pVDZ daug-cc-pVTZ daug-cc-pVQZ Sadlej_pVTZ CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF         7.6306
1
7.6162
1
7.6281
1
7.6124
1
7.0910
1
7.0953
1
density functional B3LYP         3.3253
1
3.2179
1
3.2912
1
3.1956
1
3.1763
1
3.2445
1
wB97X-D         3.6473
1
3.4962
1
3.5915
1
3.4643
1
3.5391
1
3.5850
1
Moller Plesset perturbation MP2         5.0660
1
4.2521
1
4.9417
1
3.9333
1
4.9632
1
4.9633
1
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.