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Comparison of experiment and theory for rAlAl

Species with coordinate rAlAl
Species Name
Al2 Aluminum 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 2 0.320
PM3 3 0.222
PM6 3 0.117
composite G2 3 0.213
G3 3 0.213
G3B3 2 0.290
G3MP2 1 0.162
G4 2 0.267
CBS-Q 3 0.213

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 cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ
hartree fock HF 1 0.191 3 0.293 3 0.228 3 0.254 3 0.213 3 0.213 3 0.209 3 0.230 3 0.191 3 0.401 2 0.445 3 0.140 3 0.229 3 0.218 3 0.215 3 0.393 3 0.213 3 0.213   1 0.068 1 0.060
ROHF         1 0.157                                
density functional LSDA 2 0.241 3 0.256 3 0.286 2 0.319 2 0.294 3 0.276 3 0.273 2 0.305 3 0.286 3 0.277     3 0.281 3 0.277   3 0.273 1 0.327        
SVWN   1 0.208         1 0.208         3 0.137                  
BLYP 1 0.087 3 0.328 3 0.287 3 0.303 6 0.228 3 0.280 3 0.273 3 0.295 3 0.271 3 0.276     3 0.287 3 0.279   2 0.105          
B1B95 3 0.274 3 0.236 3 0.269 3 0.270 3 0.262 3 0.261 3 0.257 3 0.273 3 0.273 3 0.258     3 0.265 3 0.260 1 0.320 3 0.256 1 0.321 1 0.316      
B3LYP 3 0.259 3 0.308 3 0.269 3 0.279 3 0.260 3 0.260 3 0.254 3 0.272 2 0.275 3 0.260 2 0.199 3 0.140 3 0.267 3 0.261 2 0.285 3 0.256 3 0.256 3 0.257   1 0.068  
B3LYPultrafine         3 0.260                       2 0.265        
B3PW91 1 0.129 3 0.305 3 0.269 3 0.273 3 0.260 3 0.260 3 0.258 3 0.273 2 0.257 3 0.262     3 0.267 3 0.262   2 0.049          
mPW1PW91 3 0.309 3 0.301 2 0.279 3 0.250 3 0.258 3 0.258 3 0.256 3 0.271 3 0.204 3 0.260     3 0.265 3 0.260   2 0.043          
M06-2X     3 0.165   2 0.202                                
PBEPBE 1 0.104 3 0.319 1 0.368 1 0.459 3 0.277 3 0.277 3 0.272 3 0.290 3 0.241 3 0.276 2 0.212   3 0.283 3 0.277 1 0.374 1 0.385 2 0.301 1 0.369      
PBEPBEultrafine         2 0.204                                
PBE1PBE         3 0.273                                
HSEh1PBE   1 0.208     1 0.208   1 0.208             1 0.208              
TPSSh         2 0.197   2 0.197     3 0.174       2 0.197              
wB97X-D     3 0.144   3 0.133   3 0.133   3 0.134     3 0.132 3 0.133 3 0.129     3 0.129        
B97D3   3 0.157     3 0.067       3 0.120               3 0.122        
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-pV(T+d)Z cc-pCVDZ cc-pCVTZ
Moller Plesset perturbation MP2 1 0.164 3 0.444 3 0.250 3 0.305 6 0.185 3 0.238 3 0.234 6 0.216 3 0.167 3 0.389   3 0.133 3 0.254 3 0.252 1 0.238 3 0.188 3 0.325 1 0.238   2 0.043 2 0.017
MP2=FULL 1 0.166 3 0.343 3 0.255 3 0.306 3 0.241 3 0.241 3 0.238 3 0.255 2 0.205 1 0.258     3 0.256 3 0.257 2 0.218 2 0.264 4 0.280     2 0.037 2 0.007
MP3         3 0.152   2 0.187                            
MP3=FULL         2 0.188   2 0.184                            
MP4   1 0.609     3 0.234     2 0.226 1 0.293                        
B2PLYP         1 0.207                 2 0.192              
B2PLYP=FULL   1 0.084     1 0.040   1 0.041                            
Configuration interaction CID   1 0.579 1 0.247 1 0.535 3 0.382     3 0.393                          
CISD   1 0.584 1 0.250 1 0.539 3 0.376     1 0.290                          
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-pV(T+d)Z cc-pCVDZ cc-pCVTZ
Quadratic configuration interaction QCISD   3 0.373 1 0.240 1 0.580 3 0.225 3 0.225 3 0.360 3 0.240 1 0.282 1 0.272     3 0.362 3 0.228              
QCISD(T)         3 0.228     2 0.394         1 0.347 1 0.282   1 0.325 1 0.276        
Coupled Cluster CCD   2 0.439 1 0.236 1 0.569 3 0.225 1 0.256 1 0.244 3 0.238 1 0.275 1 0.270     2 0.264 1 0.273   1 0.310 1 0.268        
CCSD         3 0.225     2 0.416                          
CCSD(T)         3 0.228 2 0.210   2 0.399     2 0.016   3 0.206 3 0.164 1 0.268 3 0.195 3 0.161   1 0.021 2 0.058 2 0.022
CCSD(T)=FULL         3 0.148               2 0.051 2 0.005 1 0.252 2 0.056 2 0.008     2 0.052 2 0.015
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-pV(T+d)Z cc-pCVDZ cc-pCVTZ

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 3 0.255 3 0.181 3 0.261 3 0.180 3 0.294 3 0.363
density functional B1B95 2 0.134 1 0.169        
B3LYP 3 0.292 3 0.227 3 0.290 3 0.223 3 0.323 3 0.355
Moller Plesset perturbation MP2 3 0.289 3 0.165 3 0.292 3 0.165 3 0.324 3 0.374
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.