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III.G.1.a.

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 1.6932
5
PM6 1.7138
5
composite G2 1.7508
5
G3 1.7508
5
G3B3 1.7534
5
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
hartree fock HF 1.6220
4
1.7587
5
1.7536
5
1.7604
5
1.7422
8
1.7463
5
1.7379
5
1.7468
5
1.7421
5
1.7372
5
1.7152
3
1.7336
5
1.7449
5
1.7691
2
1.7337
5
1.7632
2
1.7326
5
1.7306
5
1.7099
2
1.7066
2
ROHF   1.7502
1
1.7439
1
  1.7409
1
1.7362
1
1.7362
1
1.7363
1
                       
density functional LSDA 1.6482
5
1.7708
5
1.7654
5
1.7750
5
1.7606
5
1.7569
5
1.7511
5
1.7570
5
1.7530
5
1.7471
5
    1.7596
5
1.7466
5
1.7786
2
1.7511
5
1.7724
2
1.7688
2
   
SVWN   1.7776
5
    1.7606
5
  1.7511
5
                         
BLYP 1.6751
4
1.7782
5
1.7675
5
1.7788
5
1.7658
5
1.7614
5
1.7549
5
1.7636
5
1.7592
5
1.7526
5
    1.8107
2
1.7948
2
  1.7308
3
       
B1B95 1.6448
5
1.7624
5
1.7581
5
1.7662
5
1.7531
5
1.7504
5
1.7438
5
1.7512
5
1.7473
5
1.7415
5
    1.7513
5
1.7408
5
1.7709
2
1.7433
5
1.7651
2
1.7611
2
   
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
1.7881
2
1.7409
5
1.7156
3
1.7395
5
1.7503
5
1.7794
2
1.7376
5
1.7774
2
1.7355
5
1.7320
5
1.7057
2
1.7010
2
B3LYPultrafine         1.7533
5
                      1.7153
3
     
B3PW91 1.7352
2
1.7720
5
1.7625
5
1.7692
5
1.7560
5
1.7520
5
1.7461
5
1.7526
5
1.7878
2
1.7435
5
    1.7940
2
1.7788
2
  1.7238
3
       
mPW1PW91 1.7020
3
1.7697
5
1.7945
2
1.7669
5
1.7537
5
1.7497
5
1.7440
5
1.7501
5
1.7460
5
1.7411
5
    1.7905
2
1.7755
2
  1.7222
3
       
M06-2X         1.7435
5
                             
PBEPBE 1.7538
2
1.7849
5
1.8118
2
1.8299
2
1.7690
5
1.7651
5
1.7591
5
1.7660
5
1.7619
5
1.7560
5
1.7301
3
  1.7666
5
1.7561
5
1.7881
2
    1.7772
2
   
PBEPBEultrafine         1.7413
3
                             
PBE1PBE         1.7564
5
                             
HSEh1PBE         1.7564
5
                             
TPSSh         1.7431
5
  1.7363
5
            1.7307
5
           
Moller Plesset perturbation MP2 1.7156
2
1.7727
5
1.7584
5
1.7742
5
1.7553
5
1.7401
5
1.7328
5
1.7512
5
1.7371
5
1.7485
3
  1.7292
5
1.7411
5
1.7694
2
1.7518
3
1.7613
3
1.7334
5
1.7481
3
1.7056
2
1.7038
2
MP2=FULL 1.7162
2
1.7732
5
1.7906
2
1.8171
2
1.7550
5
1.7398
5
1.7326
5
1.7516
5
1.7726
2
1.7547
2
    1.7785
2
1.7571
2
1.7361
3
1.7156
3
  1.7342
2
1.7029
2
1.6930
2
MP3         1.7602
5
  1.7323
5
                         
MP3=FULL         1.7491
5
  1.7276
5
                         
MP4   1.7884
5
    1.7651
5
    1.7355
3
1.7762
2
        1.7418
5
           
B2PLYP         1.7513
5
                1.7273
5
           
Configuration interaction CID   1.8304
2
1.8046
2
1.8369
2
1.7666
5
    1.7640
5
                       
CISD   1.7950
5
1.8099
2
1.8435
2
1.7707
5
    1.8092
2
                       
Quadratic configuration interaction QCISD   1.7963
5
1.7845
5
1.8452
2
1.7714
5
1.7483
5
1.7417
5
1.7683
5
1.7439
5
1.7627
2
    1.7474
5
1.7447
5
           
QCISD(T)         1.7352
4
1.7251
3
1.7251
3
1.7417
3
        1.7864
2
1.7785
2
  1.7843
2
1.7718
2
     
Coupled Cluster CCD   1.7912
5
1.8050
2
1.8379
2
1.7671
5
1.7446
5
1.7379
5
1.7646
5
1.7773
2
1.7592
2
    1.7439
5
1.7767
2
  1.7811
2
1.7690
2
  1.7067
2
1.7084
2
CCSD         1.7714
5
1.7244
3
1.7244
3
1.7409
3
                       
CCSD(T)   1.7993
1
    1.7466
3
1.7251
3
1.7250
3
1.7416
3
1.7414
1
  1.7444
1
  1.7477
5
1.7452
5
  1.7517
5
1.7433
5
  1.7088
2
1.7100
2
CCSD(T)=FULL         1.7949
3
              1.7100
2
1.6963
2
        1.7068
2
1.7002
2

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 1.7815
5
1.7562
5
1.7562
5
1.7510
5
1.7450
5
1.7489
5
density functional B1B95 1.7619
3
1.7355
3
       
B3LYP 1.7831
5
1.7615
5
1.7677
5
1.7598
5
1.7499
5
1.7541
5
Moller Plesset perturbation MP2 1.7976
5
1.7709
5
1.7714
5
1.7580
5
1.7610
5
1.7633
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.