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Comparison of experiment and theory for rMgMg

Species with coordinate rMgMg
Species Name
Mg2 Magnesium diatomic
The small prefix is the number of bonds with completed calculations.
Click on an entry for a histogram of the difference distribution.
rms differences (calculated - experiment) in Å
Methods with predefined basis sets
semi-empirical AM1 1 0.903
PM3 2 1.548
PM6 1 2.185
composite G2 2 1.366
G3 2 3.109
G3B3 2 0.209
G4 1 1.208
CBS-Q 2 1.366

rms differences (calculated - experiment) in 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
hartree fock HF 1 1.024 2 1.360 2 1.392 2 1.356 2 1.366 2 1.366 2 1.361 2 3.109 1 3.069 2 1.373 2 2.178 1 3.631 1 3.605 1 3.572 1 3.563 1 3.603 1 3.569 1 3.562
density functional LSDA 2 1.247 2 0.629 2 0.704 2 0.485 2 0.510 2 0.510 2 0.508 2 0.513 2 0.513 2 0.535   1 0.480 2 0.505 2 0.520   2 0.506 1 0.518  
SVWN   2 0.543     1 0.510 1 0.510 1 0.508 1 0.513 1 0.513 1 0.535   1 0.480 1 0.505 1 0.520   1 0.506 1 0.518  
BLYP 1 1.176 2 0.223 2 0.482 2 0.163 3 0.698 2 0.030 2 0.027 2 0.034 2 0.033 2 0.122   1 5.023 1 0.015 1 0.021   2 0.026    
B1B95 2 1.172 2 0.045 2 0.515 2 0.128 2 0.212 2 0.224 2 0.224 2 0.207 2 0.207 2 0.248   1 0.226 2 0.217 2 0.188   2 0.209 1 0.189  
B3LYP 1 1.165 2 0.311 2 0.437 2 0.264 2 0.035 2 0.035 2 0.038 2 0.036 1 0.036 2 0.055 2 0.011 1 5.542 2 0.035 1 0.045 2 0.051 1 0.026 2 0.035 2 0.046
B3LYPultrafine         2 0.035             1 5.962 1 0.039 1 0.046   1 0.028 1 1.208  
B3PW91 1 1.187 2 0.189 2 0.528 2 0.219 2 0.287 2 0.287 2 0.285 2 0.282 1 0.281 2 0.307   1 0.089 1 0.286 1 0.283   2 0.288    
mPW1PW91 2 0.754 2 0.204 1 0.527 2 0.231 2 0.299 2 0.299 2 0.299 2 0.294 2 0.292 2 0.313   1 0.116 1 0.298 1 0.291   2 0.300 1 0.291  
M06-2X 1 1.153 1 0.078 2 0.911 1 0.074 2 0.108 1 0.108 1 0.107 1 0.105 1 0.105 1 0.142   1 0.310 1 0.102 1 0.094   1 0.103 1 0.093  
PBEPBE 1 1.209 2 0.398 1 0.607 1 0.354 2 0.392 2 0.392 2 0.392 2 0.390 2 0.390 2 0.412 2 0.398 1 0.300 2 0.391 2 0.389   1 0.393 1 0.388  
PBEPBEultrafine         2 0.390             1 0.299 1 0.389 1 0.387   1 0.392 1 0.387  
PBE1PBE 1 1.191 1 0.543 1 0.543 1 0.250 1 0.314 1 0.314 1 0.313 1 0.308 1 0.308 1 0.329   1 0.147 1 0.314 1 0.306   1 0.315 1 0.305  
HSEh1PBE 1 1.188 2 0.249 1 0.552 1 0.257 2 0.320 1 0.320 1 0.320 1 0.315 1 0.315 1 0.338   1 0.153 1 0.318 2 0.315   1 0.320 1 0.313  
TPSSh   1 0.186 1 0.532 1 0.262 1 1.208 1 0.336 1 1.208 1 0.335   1 1.208   1 0.128 1 0.341 1 1.208   1 0.343 1 0.339  
wB97X-D     1 1.208   1 1.208   1 1.208   1 1.208     1 1.208 1 1.208 1 1.208     1 1.208  
B97D3   1 1.208     1 1.208       1 1.208               1 1.208  
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
Moller Plesset perturbation MP2 1 1.043 2 1.305 2 0.056 2 1.293 3 1.286 2 1.324 2 0.554 3 0.810 2 0.506 2 1.332   2 2.200 2 0.743 1 0.243 2 0.243 1 0.577 2 0.248 2 0.245
MP2=FULL 1 1.069 2 1.306 1 0.169 1 1.359 2 0.502 2 0.500 2 1.338 2 0.424 1 0.427 1 0.109   1 2.148 1 0.932 1 0.932 2 0.197 2 0.756 2 0.659 1 0.277
MP3         2 0.354   1 1.208         1 1.922 1 0.556 1 0.123        
MP3=FULL         1 1.208   1 0.310         1 1.872 1 0.545 1 0.132        
MP4   1 1.162     2 1.221     2 0.338 1 0.339     1 1.873 1 0.608 2 0.066   1 0.382 1 0.071  
MP4=FULL   1 1.138     1 0.264       1 0.274       1 0.596 1 0.185   1 0.353 1 0.228  
B2PLYP         1 0.315                 1 1.208        
Configuration interaction CID   1 1.261 1 0.578 1 1.823 1 0.915     2 0.920                    
CISD   1 1.253 1 0.612 1 1.822 1 0.917     1 0.969                    
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
Quadratic configuration interaction QCISD   2 1.232 1 0.776 1 1.970 2 1.296 1 1.463 2 1.358 2 1.296 1 1.298 1 0.657   1 1.949 2 1.519 2 0.679   1 1.119 1 0.633  
QCISD(T)         1 0.870     1 0.646       1 1.893 1 1.058 1 0.166   1 0.642 1 0.163  
Coupled Cluster CCD   1 1.342 1 0.752 1 1.983 2 1.315 1 1.418 1 1.293 2 1.251 1 1.245 1 0.597   1 1.902 2 1.490 1 0.620 1 0.508 1 1.055 1 0.589 1 0.511
CCSD         2 1.300     2 1.285       1 1.952 1 1.513 1 0.687 1 0.557 1 1.118 1 0.646 1 0.554
CCSD=FULL         1 1.269             1 1.903 1 1.399 1 0.120 1 0.252 1 0.980 1 0.024 1 0.220
CCSD(T)         2 0.870 2 1.096   2 0.645     2 0.127 1 1.887 2 1.055 2 0.168 1 0.085 2 0.641 2 0.165 1 0.087
CCSD(T)=FULL         1 0.766             1 1.838 1 0.995   1 0.070 1 0.580 1 0.194 1 0.093
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

rms differences (calculated - experiment) in Å
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 2 2.066 1 3.604 1 3.614 1 3.603 1 3.613 2 3.109
density functional B1B95 2 0.061 1 0.152        
B3LYP 1 0.250 1 0.088 1 0.246 1 0.078 1 0.071 1 0.264
Moller Plesset perturbation MP2 1 1.475 1 0.550 2 1.343 2 0.404 2 1.410 1 1.415
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.