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Comparison of levels of theory for Mg-H


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 2.2228
2
PM3 1.6970
3
PM6 1.7138
5
composite G2 1.7508
5
G3 1.7508
5
G3B3 1.7533
5
G3MP2 1.7281
3
G4 1.7415
5
CBS-Q 1.7508
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-pCVDZ cc-pCVTZ daug-cc-pVDZ daug-cc-pVTZ
hartree fock HF 1.6163
5
1.7587
5
1.7536
5
1.7604
5
1.7507
5
1.7463
5
1.7379
5
1.7468
5
1.7421
5
1.7372
5
1.7152
3
1.7336
5
1.7449
5
1.7385
5
1.7337
5
1.7370
5
1.7326
5
1.7306
5
1.7099
2
1.7066
2
1.7403
1
1.7324
5
ROHF   1.7502
1
1.7439
1
1.7509
1
1.7409
1
1.7362
1
1.7362
1
1.7363
1
1.7313
1
  1.7270
1
1.7281
1
1.7331
1
1.7301
1
1.7271
1
1.7328
1
1.7290
1
1.7271
1
    1.7326
1
1.7289
1
density functional LSDA 1.6485
5
1.7708
5
1.7654
5
1.7753
5
1.7606
5
1.7569
5
1.7511
5
1.7568
5
1.7530
5
1.7471
5
  1.7051
2
1.7596
5
1.7466
5
1.7786
2
1.7511
5
1.7391
4
1.7688
2
       
BLYP 1.6710
5
1.7782
5
1.7675
5
1.7788
5
1.7498
5
1.7614
5
1.7549
5
1.7636
5
1.7592
5
1.7526
5
1.7568
1
1.7286
3
1.7631
5
1.7534
5
  1.7308
3
1.7246
3
      1.7642
1
1.7563
1
B1B95 1.6448
5
1.7679
1
1.7581
5
1.7662
5
1.7531
5
1.7504
5
1.7438
5
1.7493
5
1.7473
5
1.7415
5
1.7399
1
1.7184
3
1.7513
5
1.7408
5
1.7709
2
1.7433
5
1.7350
5
1.7611
2
    1.7483
1
1.7397
1
B3LYP 1.6518
5
1.7659
5
1.7560
5
1.7660
5
1.7534
5
1.7491
5
1.7427
5
1.7509
5
1.7468
5
1.7409
5
1.7156
3
1.7395
5
1.7503
5
1.7413
5
1.7375
5
1.7430
5
1.7355
5
1.7320
5
1.7057
2
1.7010
2
1.7499
1
1.7428
1
B3LYPultrafine   1.7391
3
    1.7533
5
1.7221
3
1.7222
3
1.7223
3
  1.7439
1
1.7428
1
1.7165
3
1.7210
3
1.7158
3
  1.7200
3
1.7153
3
      1.7499
1
1.7428
1
B3PW91 1.6475
5
1.7720
5
1.7625
5
1.7692
5
1.7560
5
1.7520
5
1.7461
5
1.7526
5
1.7485
5
1.7435
5
1.7420
1
1.7201
3
1.7526
5
1.7430
5
  1.7238
3
1.7181
3
      1.7497
1
1.7424
1
mPW1PW91 1.6474
5
1.7697
5
1.7602
5
1.7669
5
1.7537
5
1.7497
5
1.7440
5
1.7501
5
1.7460
5
1.7411
5
1.7397
1
1.7177
3
1.7501
5
1.7407
5
  1.7222
3
1.7164
3
      1.7474
1
1.7401
1
M06-2X 1.5768
3
1.7269
3
1.7434
5
1.7271
3
1.7435
5
1.7159
3
1.7160
3
1.7149
3
1.7126
3
1.7112
3
1.7280
5
1.7082
3
1.7151
3
1.7096
3
  1.7141
3
1.7084
3
      1.7477
1
1.7384
1
PBEPBE 1.6638
5
1.7849
5
1.7743
5
1.7834
5
1.7690
5
1.7651
5
1.7591
5
1.7660
5
1.7619
5
1.7560
5
1.7301
3
1.7325
3
1.7666
5
1.7561
5
1.7881
2
1.7357
3
1.7288
3
1.7772
2
    1.7654
1
1.7569
1
PBEPBEultrafine   1.7577
3
    1.7413
3
1.7379
3
1.7380
3
1.7369
3
  1.7587
1
1.7573
1
1.7324
3
1.7372
3
1.7298
3
  1.7356
3
1.7287
3
      1.7654
1
1.7569
1
PBE1PBE 1.5864
3
1.7626
1
1.7388
3
1.7413
3
1.7564
5
1.7311
3
1.7274
3
1.7261
3
1.7227
3
1.7204
3
1.7430
1
1.7203
3
1.7256
3
1.7199
3
  1.7243
3
1.7189
3
      1.7510
1
1.7434
1
HSEh1PBE 1.5867
3
1.7716
5
1.7386
3
1.7409
3
1.7565
5
1.7269
3
1.7461
5
1.7259
3
1.7227
3
1.7203
3
1.7430
1
1.7202
3
1.7253
3
1.7433
5
  1.7238
3
1.7185
3
      1.7510
1
1.7434
1
TPSSh 1.5879
3
1.7489
3
1.7410
3
1.7430
3
1.7431
5
1.7281
3
1.7363
5
1.7255
3
1.7221
3
1.7323
5
1.7437
1
1.7193
3
1.7255
3
1.7307
5
1.7183
3
1.7242
3
1.7188
3
1.7172
3
    1.7522
1
1.7446
1
wB97X-D 1.5851
3
1.7493
3
1.7528
5
1.7383
3
1.7409
5
1.7258
3
1.7325
5
1.7250
3
1.7319
5
1.7190
3
1.7379
1
1.7275
5
1.7307
5
1.7280
5
1.7156
3
1.7219
3
1.7253
5
1.7143
3
    1.7455
1
1.7393
1
B97D3 1.6075
3
1.7938
5
1.7583
3
1.7607
3
1.7773
5
1.7457
3
1.7642
5
1.7447
3
1.7690
5
1.7389
3
1.7560
5
1.7614
5
1.7445
3
1.7626
5
1.7367
3
1.7430
3
1.7553
5
1.7339
3
    1.7850
1
1.7538
5
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-pCVDZ cc-pCVTZ daug-cc-pVDZ daug-cc-pVTZ
Moller Plesset perturbation MP2 1.6284
5
1.7727
5
1.7584
5
1.7742
5
1.7449
5
1.7401
5
1.7328
5
1.7400
5
1.7371
5
1.7295
5
1.7313
1
1.7292
5
1.7411
5
1.7364
5
1.7327
5
1.7412
5
1.7334
5
1.7309
5
1.7056
2
1.7038
2
1.7408
1
1.7325
1
MP2=FULL 1.6496
5
1.7732
5
1.7579
5
1.7748
5
1.7550
5
1.7398
5
1.7326
5
1.7516
5
1.7367
5
1.7250
5
1.7284
1
1.7045
3
1.7409
5
1.7240
5
1.7206
5
1.7158
3
1.6986
3
1.7093
5
1.7029
2
1.6930
2
1.7346
1
1.7263
1
ROMP2 1.6004
1
1.7497
1
1.7497
1
1.7649
1
1.7463
1
1.7313
1
1.7313
1
1.7419
1
1.7280
1
1.7247
1
1.7300
1
1.7266
1
1.7313
1
1.7296
1
  1.7387
1
        1.7385
1
1.7313
1
MP3         1.7602
5
  1.7323
5
      1.7343
1
1.7070
3
1.7154
3
1.7163
3
            1.7439
1
1.7352
1
MP3=FULL   1.7560
3
1.7403
3
1.7543
3
1.7491
5
1.7163
3
1.7276
5
1.7308
3
1.7129
3
1.7045
3
1.7313
1
1.7055
3
1.7153
3
1.7033
3
  1.7182
3
1.6999
3
      1.7385
1
1.7287
1
MP4   1.7884
5
    1.7651
5
    1.7355
3
1.7396
5
  1.7383
1
1.7095
3
1.7173
3
1.7419
5
  1.7255
3
1.7204
3
      1.7471
1
1.7394
1
MP4=FULL   1.7616
3
    1.7395
3
      1.7148
3
  1.7346
1
  1.7173
3
1.7052
3
  1.7203
3
1.7018
3
      1.7418
1
1.7313
1
B2PLYP 1.5806
3
1.7393
3
1.7307
3
1.7365
3
1.7513
5
1.7183
3
1.7184
3
1.7213
3
1.7026
2
1.7119
3
1.7367
1
1.7110
3
1.7169
3
1.7273
5
  1.7182
3
1.7128
3
      1.7447
1
1.7371
1
B2PLYP=FULL 1.5810
3
1.7392
3
1.7306
3
1.7367
3
1.7252
3
1.7181
3
1.7178
3
1.7213
3
1.7147
3
1.7103
3
1.7357
1
1.7102
3
1.7169
3
1.7090
3
  1.7166
3
1.7073
3
      1.7429
1
1.7344
1
B2PLYP=FULLultrafine 1.5810
3
1.7395
3
1.7305
3
1.7366
3
1.7512
5
1.7181
3
1.7182
3
1.7213
3
1.7146
3
1.7102
3
1.7357
1
1.7101
3
1.7441
5
1.7328
5
  1.7165
3
1.7263
5
      1.7429
1
1.7344
1
Configuration interaction CID   1.7903
5
1.7699
5
1.7919
5
1.7666
5
    1.7640
5
    1.7393
1
  1.7385
1
1.7387
1
            1.7490
1
1.7406
1
CISD   1.7950
5
1.7740
5
1.7970
5
1.7707
5
    1.7675
5
    1.7435
1
  1.7438
1
1.7429
1
            1.7535
1
1.7446
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 cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pCVDZ cc-pCVTZ daug-cc-pVDZ daug-cc-pVTZ
Quadratic configuration interaction QCISD   1.7963
5
1.7845
5
1.7983
5
1.7714
5
1.7483
5
1.7417
5
1.7683
5
1.7437
5
1.7335
5
1.7435
1
1.7138
3
1.7473
5
1.7447
5
  1.7286
3
1.7233
3
      1.7535
1
1.7447
1
QCISD(T)         1.7352
4
1.7251
3
1.7251
3
1.7417
3
    1.7445
1
1.7137
3
1.7476
5
1.7450
5
  1.7514
5
1.7430
5
      1.7545
1
1.7456
1
QCISD(T)=FULL         1.7462
3
  1.7240
3
      1.7412
1
  1.7218
3
1.7086
3
1.7111
3
1.7242
3
1.7051
3
1.6989
3
    1.7484
1
1.7377
1
QCISD(TQ)         1.7466
3
  1.7245
3
      1.7448
1
  1.7218
3
1.7228
3
1.7211
3
1.7297
3
1.7239
3
1.7219
3
    1.7548
1
1.7459
1
QCISD(TQ)=FULL         1.7464
3
  1.7242
3
      1.7416
1
  1.7219
3
1.7089
3
1.7113
3
1.7244
3
1.7054
3
1.6992
3
    1.7488
1
1.7380
1
Coupled Cluster CCD   1.7912
5
1.7705
5
1.7928
5
1.7671
5
1.7446
5
1.7379
5
1.7646
5
1.7405
5
1.7306
5
1.7393
1
1.7111
3
1.7437
5
1.7424
5
  1.7483
5
1.7404
5
  1.7067
2
1.7084
2
1.7490
1
1.7406
1
CCSD         1.7714
5
1.7244
3
1.7244
3
1.7409
3
1.7403
1
1.7139
3
1.7433
1
1.7137
3
1.7212
3
1.7219
3
1.7202
3
1.7285
3
1.7232
3
1.7210
3
    1.7533
1
1.7444
1
CCSD=FULL         1.7451
3
        1.7093
3
1.7396
1
1.7120
3
1.7213
3
1.7079
3
1.7103
3
1.7236
3
1.7044
3
1.6989
3
    1.7478
1
1.7360
1
CCSD(T)         1.7466
3
1.7251
3
1.7250
3
1.7416
3
1.7194
3
1.7147
3
1.7444
1
1.7137
3
1.7477
5
1.7452
5
1.7205
3
1.7517
5
1.7433
5
1.7217
3
1.7088
2
1.7100
2
1.7543
1
1.7454
1
CCSD(T)=FULL         1.7890
4
          1.7411
1
1.7126
3
1.7217
3
1.7086
3
1.7110
3
1.7241
3
1.7051
3
1.6989
3
1.7068
2
1.7002
2
1.7483
1
1.7375
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 cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pCVDZ cc-pCVTZ daug-cc-pVDZ daug-cc-pVTZ

average calculated bond lengths (Å)
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD cc-pVTZ-PP aug-cc-pVTZ-PP Def2TZVPP
hartree fock HF 1.7815
5
1.7562
5
1.7562
5
1.7510
5
1.7450
5
1.7489
5
    1.7268
5
ROHF                 1.7280
1
density functional BLYP                 1.7552
1
B1B95 1.7619
3
1.7355
3
            1.7406
1
B3LYP 1.7831
5
1.7615
5
1.7677
5
1.7598
5
1.7499
5
1.7541
5
    1.7286
5
B3LYPultrafine                 1.7421
1
B3PW91                 1.7426
1
mPW1PW91                 1.7403
1
M06-2X                 1.7377
1
PBEPBE                 1.7421
5
PBEPBEultrafine                 1.7570
1
PBE1PBE                 1.7436
1
HSEh1PBE                 1.7436
1
TPSSh                 1.7442
1
wB97X-D 1.7638
3
1.7382
3
1.7388
3
1.7357
3
1.7250
3
1.7336
3
    1.7388
1
B97D3                 1.7777
1
Moller Plesset perturbation MP2 1.7976
5
1.7709
5
1.7714
5
1.7580
5
1.7610
5
1.7633
5
    1.7230
5
MP2=FULL                 1.7187
1
ROMP2                 1.7251
1
MP3                 1.7293
1
MP3=FULL                 1.7215
1
MP4=FULL                 1.7252
1
B2PLYP                 1.7342
1
B2PLYP=FULL                 1.7323
1
B2PLYP=FULLultrafine                 1.7323
1
Configuration interaction CID                 1.7336
1
CISD                 1.7380
1
Quadratic configuration interaction QCISD                 1.7380
1
QCISD(T)                 1.7386
1
QCISD(T)=FULL                 1.7313
1
QCISD(TQ)                 1.7389
1
QCISD(TQ)=FULL                 1.7321
1
Coupled Cluster CCD                 1.7336
1
CCSD                 1.7378
1
CCSD=FULL                 1.7305
1
CCSD(T)                 1.7385
1
CCSD(T)=FULL                 1.7313
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.