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Comparison of levels of theory for Mg-Mg


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 3.9498
3
PM3 2.3424
1
PM6 1.6515
3
composite G2 3.1933
3
G3 4.6852
3
G3B3 3.7312
3
G4 3.2270
3
CBS-Q 3.1933
3

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 2.6781
2
3.2638
3
3.1181
3
3.2632
3
3.1931
3
3.1933
3
3.1378
3
4.6818
3
4.6684
3
3.1990
3
2.6829
1
4.4689
3
2.9491
3
4.8439
3
4.8277
3
4.8158
3
4.8119
3
4.8026
3
5.0329
3
density functional LSDA 2.5658
2
3.0163
3
3.0163
3
3.1730
3
3.1504
3
3.1504
3
3.2794
3
3.1478
3
3.1478
3
3.1322
3
  3.4108
1
  3.1533
3
3.1444
3
3.2447
2
3.2844
3
3.2717
3
3.2194
2
BLYP 2.6223
2
3.7991
3
3.4106
3
3.8189
3
2.9445
3
3.7246
3
3.5825
3
3.6971
3
3.6974
3
3.6458
3
  8.9135
1
  3.7113
3
3.6677
3
  3.8641
1
   
B1B95 2.6094
2
  3.2991
3
3.5382
3
3.4923
3
3.4882
3
3.6230
2
3.4860
3
3.4860
3
3.4645
3
  4.1167
1
  3.4885
3
3.4777
3
3.3439
2
3.4436
3
3.4507
3
3.3211
2
B3LYP 2.6196
2
3.7625
3
3.3644
3
3.7512
3
3.6449
3
3.6449
3
3.5678
3
3.6290
3
3.6290
3
3.5874
3
3.9018
1
5.1029
3
2.9853
3
3.6366
3
3.6125
3
3.5989
3
3.5775
3
3.5766
3
3.5795
3
B3LYPultrafine         3.6450
3
            9.8524
1
  3.9299
1
3.9367
1
  3.9189
1
2.8952
2
 
B3PW91 2.6030
2
3.5236
3
3.2975
3
3.5074
3
3.4636
3
3.4636
3
3.4119
3
3.4552
3
3.4554
3
3.4454
3
  3.8018
1
  3.4601
3
3.4409
3
  3.6026
1
   
mPW1PW91 2.8170
2
3.5077
3
3.2920
3
3.4917
3
3.4480
3
3.4480
3
3.3994
3
3.4411
3
3.4416
3
3.4345
3
  3.7747
1
  3.4447
3
3.4300
3
  3.5905
1
3.5997
1
 
M06-2X 2.7370
1
3.9690
1
3.1397
3
3.8165
1
3.3568
3
3.7823
1
3.7834
1
3.7851
1
3.7851
1
3.7487
1
  4.2000
1
  3.7881
1
3.7963
1
  3.7874
1
3.7974
1
 
PBEPBE 2.5964
2
3.4481
3
3.2654
3
3.4653
3
3.4373
3
3.4373
3
3.3734
3
3.4247
3
3.4247
3
3.4167
3
3.4923
1
3.5907
1
2.9204
3
3.4333
3
3.4123
3
3.3452
2
3.4974
1
3.5022
1
3.3160
2
PBEPBEultrafine         3.5001
1
            3.5912
1
  3.5011
1
3.5031
1
  3.4987
1
3.5031
1
 
PBE1PBE 2.6998
1
  3.3471
1
3.6404
1
3.4415
3
3.5766
1
3.5770
1
3.5825
1
3.5825
1
3.5615
1
  3.7434
1
  3.5769
1
3.5843
1
  3.5757
1
3.5854
1
 
HSEh1PBE 2.7024
1
3.2610
3
3.3384
1
3.6336
1
3.2595
3
3.5704
1
3.2774
3
3.5756
1
3.5756
1
3.5523
1
  3.7379
1
  3.5723
1
3.2650
3
  3.5706
1
3.5773
1
 
TPSSh   3.7046
1
3.3590
1
3.6287
1
2.9234
3
3.5543
1
2.9292
3
3.5552
1
  2.9223
3
  3.7630
1
  3.5499
1
2.9257
3
  3.5479
1
3.5513
1
 
wB97X-D     2.9105
3
  2.9249
3
  2.9369
3
  2.9274
3
    2.9105
3
  2.9369
3
2.9284
3
    2.9387
3
 
B97D3   2.9485
3
    2.9463
3
  2.9511
3
  2.9460
3
  2.9493
3
      2.9467
3
    3.4545
3
 
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 2.6671
2
3.2506
3
3.4939
3
3.2394
3
2.9226
3
3.1059
3
3.6908
3
2.9287
3
3.7123
3
3.1052
3
  3.9822
3
2.9149
3
3.7866
3
3.6131
3
3.6243
3
3.7241
3
3.6041
3
3.6142
3
MP2=FULL 2.6507
2
3.2490
3
3.3989
3
4.1227
3
3.6959
3
3.6950
3
3.0411
3
3.6793
3
3.6802
3
3.4551
3
  6.0381
1
  3.2138
3
3.1672
3
3.5877
3
2.9588
1
3.9069
1
3.5713
3
MP3         3.6410
3
  2.9191
3
        5.8128
1
  4.4465
1
4.0134
1
       
MP3=FULL         2.9159
3
  3.4433
3
        5.7622
1
  4.4352
1
3.7586
1
       
MP4   4.0944
3
    3.1043
3
    4.2287
1
3.6236
3
    5.7632
1
  4.4981
1
3.5270
3
  4.2729
1
3.9612
1
 
MP4=FULL   5.0289
1
    4.1549
1
      4.1648
1
        4.4862
1
3.7053
1
  4.2433
1
3.6628
1
 
B2PLYP         3.4965
3
                  2.9379
3
       
Configuration interaction CID   4.1364
3
3.6474
3
4.3259
3
3.8308
3
    3.8329
3
                     
CISD   4.1293
3
3.6632
3
4.3188
3
3.8356
3
    3.8526
3
                     
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   3.3080
3
3.7137
3
4.3803
3
3.0939
3
4.0133
3
3.9448
3
3.9581
3
3.9587
3
3.7645
3
  5.8397
1
  4.0207
3
3.7492
3
  5.0092
1
4.5240
1
 
QCISD(T)         3.8039
3
    4.5367
1
      5.7833
1
  3.8560
3
3.5645
3
  3.7230
3
3.5565
3
 
Coupled Cluster CCD   4.1751
3
3.7019
3
4.3984
3
3.0845
3
3.9956
3
3.9238
3
3.9420
3
3.9400
3
3.7395
3
  5.7927
1
  4.0096
3
3.7285
3
4.3990
1
3.8766
3
3.7131
3
4.4020
1
CCSD         3.0941
3
    5.1750
1
      5.8422
1
  5.4034
1
4.5772
1
4.4473
1
5.0084
1
4.5360
1
4.4442
1
CCSD=FULL         5.1600
1
            5.7940
1
  5.2894
1
4.0109
1
4.1422
1
4.8704
1
3.9142
1
4.1107
1
CCSD(T)         4.7609
1
2.6078
1
  4.5354
1
    4.0177
1
5.7775
1
  3.8558
3
3.5661
3
3.9753
1
3.7238
3
3.5580
3
3.9775
1
CCSD(T)=FULL         4.6567
1
            5.7282
1
  4.8850
1
  3.8203
1
4.4702
1
3.6969
1
3.7980
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         3.9296
3
4.8368
3
4.8862
3
4.8220
3
4.8689
3
4.3517
3
density functional B1B95         3.8294
1
3.7383
1
       
B3LYP         3.7472
3
3.6493
3
3.7249
3
3.6260
3
3.6452
3
3.4138
3
Moller Plesset perturbation MP2         4.1748
3
3.7508
3
4.0876
3
3.6747
3
4.1139
3
3.7764
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.