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III.G.1.a.

Comparison of levels of theory for Mg-Li


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 PM6 3.3010
1
composite G2 3.1035
1
G3 3.1035
1
G3B3 3.0445
1
G4 3.3686
1
CBS-Q 3.1035
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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF 2.3811
1
3.3791
1
3.2638
1
3.5354
1
3.4597
1
3.4597
1
3.4439
1
3.4058
1
3.4058
1
3.4321
1
7.9294
1
3.4376
1
3.4085
1
3.4041
1
3.4309
1
3.4064
1
3.4041
1
ROHF   3.3791
1
3.2638
1
3.5354
1
3.4597
1
3.4597
1
3.4439
1
3.4058
1
3.4058
1
  7.9294
1
3.4376
1
3.4085
1
3.4041
1
3.4309
1
3.4064
1
3.4041
1
density functional LSDA 2.4004
1
2.9665
1
2.9665
1
3.0456
1
3.0405
1
3.0405
1
3.0380
1
3.0149
1
3.0149
1
3.0116
1
3.0395
1
3.0277
1
3.0134
1
  3.0235
1
3.0128
1
 
SVWN   2.9932
1
    3.0405
1
3.0405
1
3.0380
1
3.0149
1
3.0149
1
3.0116
1
  3.0277
1
3.0134
1
  3.0235
1
3.0128
1
 
BLYP 2.4262
1
3.0564
1
3.0244
1
3.1375
1
3.1304
1
3.1304
1
3.1244
1
3.1046
1
3.1046
1
3.1089
1
3.1638
1
3.1087
1
3.1069
1
       
B1B95 2.4013
1
3.0576
1
3.0576
1
3.1489
1
3.1477
1
3.1477
1
3.1432
1
3.1242
1
3.1242
1
3.1301
1
3.1851
1
3.1353
1
3.1282
1
    3.1268
1
 
B3LYP 2.4101
1
3.0583
1
3.0267
1
3.1362
1
3.1287
1
3.1287
1
3.1238
1
3.1039
1
3.1039
1
3.1090
1
3.1732
1
3.1111
1
3.1063
1
3.0936
1
3.1073
1
3.1045
1
3.0963
1
B3LYPultrafine         3.1297
1
                    3.3666
1
 
B3PW91 2.4110
1
3.0655
1
3.0365
1
3.1257
1
3.1186
1
3.1186
1
3.1161
1
3.0984
1
3.0984
1
3.1019
1
3.1586
1
3.1074
1
3.0974
1
       
mPW1PW91 2.4049
1
3.0542
1
3.0267
1
3.1126
1
3.1051
1
3.1051
1
3.1020
1
3.0863
1
3.0863
1
3.0904
1
3.1476
1
3.0948
1
3.0857
1
  3.0925
1
3.0843
1
 
M06-2X 2.3827
1
3.0345
1
3.0062
1
3.1010
1
3.0868
1
3.0868
1
3.0831
1
3.0734
1
3.0734
1
3.0743
1
3.1339
1
3.0807
1
3.0737
1
  3.0768
1
3.0712
1
 
PBEPBE 2.4180
1
3.0344
1
3.0074
1
3.0917
1
3.0850
1
3.0850
1
3.0811
1
3.0669
1
3.0669
1
3.0683
1
3.1066
1
3.0722
1
3.0665
1
  3.0696
1
3.0644
1
 
PBE1PBE 2.4019
1
3.0214
1
3.0214
1
3.1044
1
3.0975
1
3.0975
1
3.0944
1
3.0784
1
3.0784
1
3.0826
1
3.1347
1
3.0868
1
3.0785
1
  3.0844
1
3.0774
1
 
HSEh1PBE 2.4050
1
3.0509
1
3.0225
1
3.1073
1
3.1006
1
3.1006
1
3.0974
1
3.0807
1
3.0807
1
3.0849
1
3.1346
1
3.0897
1
3.0808
1
  3.0877
1
3.0798
1
 
TPSSh         3.0885
1
  3.0879
1
          3.0802
1
       
Moller Plesset perturbation MP2 2.3754
1
3.3808
1
3.1763
1
5.3222
1
3.3177
1
3.3177
1
3.3044
1
3.2561
1
3.2561
1
3.2561
1
4.2264
1
3.2907
1
3.2214
1
3.1954
1
3.2832
1
3.2177
1
3.1969
1
MP2=FULL 2.3654
1
3.3626
1
3.1571
1
5.2774
1
3.2567
1
3.2567
1
3.2497
1
3.2450
1
3.2450
1
3.1165
1
4.1879
1
3.2422
1
3.1145
1
3.0817
1
3.2302
1
3.0913
1
3.0714
1
ROMP2 2.3798
1
3.2362
1
3.2362
1
3.9451
1
3.4039
1
3.4039
1
3.3863
1
3.3493
1
3.3493
1
3.3446
1
6.1676
1
3.3691
1
3.3010
1
  3.3632
1
   
MP3         3.2483
1
  3.1334
1
                   
MP3=FULL         3.1224
1
  3.1216
1
                   
MP4   5.1441
1
    3.2064
1
      3.1528
1
      3.1272
1
       
Configuration interaction CID   5.2022
1
3.1137
1
5.3490
1
3.2256
1
    3.1707
1
                 
CISD   3.3780
1
3.1194
1
3.6115
1
3.2039
1
    3.1590
1
                 
Quadratic configuration interaction QCISD   3.3709
1
3.1177
1
3.5976
1
3.1994
1
3.1994
1
3.1953
1
3.1553
1
3.1553
1
3.1608
1
3.4449
1
3.1742
1
3.1360
1
  3.1736
1
3.1345
1
 
QCISD(T)         3.1802
1
          3.4250
1
3.1576
1
3.1155
1
  3.1554
1
3.1134
1
 
Coupled Cluster CCD   5.2018
1
3.1139
1
5.3495
1
3.2256
1
3.2256
1
3.2202
1
3.1707
1
3.1707
1
3.1804
1
3.5039
1
3.1984
1
3.1530
1
  3.2003
1
3.1511
1
 
CCSD         3.2054
1
            3.1790
1
3.1394
1
       
CCSD(T)         3.1835
1
          3.4271
1
3.1604
1
3.1171
1
3.1057
1
3.1588
1
3.1149
1
3.1052
1
CCSD(T)=FULL         3.1438
1
          3.4126
1
3.1310
1
3.0381
1
3.0198
1
3.1255
1
3.0228
1
3.0108
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 3.9269
1
3.6778
1
3.5251
1
3.4242
1
3.3833
1
3.4976
1
density functional B3LYP 3.2579
1
3.2304
1
3.1788
1
3.1525
1
3.0846
1
3.1339
1
Moller Plesset perturbation MP2 5.4372
1
3.5627
1
5.2428
1
3.2720
1
3.4997
1
4.3012
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.