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XVII.C.1.

Calculated Ionization Energy for O2 (Oxygen diatomic)

Experimental Ionization Energy is 12.0697 ± 0.0002 eV
Please note! These calculated ionizataion energies have the vibrational zero-point energy (zpe) included, but the zpe has NOT been scaled. Click on an entry for more details, including the ionization energy with a scaled zpe.
Original data displayed. Press to display differences.
Differences displayed. Press to display original data.

Ionization Energies in eV
Methods with predefined basis sets
semi-empirical PM3  
composite G4 12.045
CBS-Q 12.270

Ionization Energies in eV
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 cc-pV(T+d)Z
hartree fock HF 11.123 13.548 13.548 13.382 12.406 12.406 12.442 12.274 12.274 12.145 12.262 12.215 12.131 12.127 12.291 12.172 12.141 12.131
ROHF   13.171 13.548 12.910   11.870 11.876 11.755 12.274     11.705 11.551 12.127 12.291 12.172 12.141  
density functional LSDA 10.881 13.408 13.408 13.497 12.858 12.858 13.016 12.877 12.877 12.683   12.702 12.789   12.907 12.851   12.789
SVWN   13.408     12.858 12.858 13.016 12.877 12.877 12.683   12.701 12.789   12.907 12.851    
BLYP 10.355 12.728 12.728 12.868 12.242 12.242 12.454 12.267 12.267 12.064 12.344 12.092 12.215         12.215
B1B95 10.867 13.186 13.186 13.131 12.286 12.398 12.505 12.349 12.349 12.200 12.385 12.242 12.140   12.275 12.195    
B3LYP 10.931 13.267 13.267 13.300 12.601 12.601 12.752 12.582 12.583 12.405 12.626 12.443 12.503 12.523 12.639 12.571 12.550 12.503
B3LYPultrafine         12.601           12.626 12.443 12.503   12.639 12.571    
B3PW91 10.974 13.364 13.364 13.289 12.572 12.572 12.669 12.531 12.531 12.380 12.534 12.427 12.429         12.429
mPW1PW91 11.033 13.377 13.405 13.307 12.546 12.546 12.646 12.496 12.519 12.376 12.536 12.401 12.399   12.563 12.478   12.399
M06-2X 11.031 13.451 13.451 13.343 12.531 12.531 12.629 12.535 12.535 12.345 12.503 12.367 12.455   12.506 12.502    
PBEPBE 10.417 12.856 12.856 12.895 12.244 12.244 12.410 12.241 12.241 12.075 12.303 12.107 12.188   12.318 12.269   12.188
PBEPBEultrafine         12.244           12.303 12.107 12.188   12.318 12.269    
PBE1PBE 10.927 13.326 13.326 13.243 12.504 12.504 12.607 12.453 12.453 12.314 12.480 12.359 12.369   12.500 12.428    
HSEh1PBE 10.923 13.315 13.315 13.239 12.501 12.501 12.605 12.454 12.454 12.308 12.483 12.352 12.371   12.496 12.428    
TPSSh         12.413   12.518           12.296          
Moller Plesset perturbation MP2 7.855 11.188 11.188 11.454 11.515 11.515 11.599 11.414 11.414 11.521 11.437 11.330 11.578 11.664 11.607 11.688 11.711 11.578
MP2=FULL 7.853 11.185 11.185 11.451 11.514 11.514 11.598 11.417 11.417 11.520 11.441 11.328 11.575 11.677 11.606 11.679 11.723 11.575
ROMP2         12.653 12.653 12.604 12.352 12.352 12.196   12.356 12.119   12.301      
MP3         12.120   12.319       11.969 11.854 12.085          
MP3=FULL         12.118   12.189                      
MP4   11.482     11.710       11.551   11.595 11.490 11.727   11.806 11.860    
Configuration interaction CID   12.583 12.583 12.614 12.061     11.907                    
CISD     12.561 12.617 12.060     11.904                    
Quadratic configuration interaction QCISD   12.320 12.320 12.475 11.967 11.967 12.075 11.818 11.818 11.925 11.867 11.723 11.986   12.027 12.108   11.986
QCISD(T)         11.876           11.776 11.630 11.901   11.957 12.039    
Coupled Cluster CCD   12.376 12.376 12.480 11.972 11.972 12.049 11.823 11.823 11.927 11.850 11.733 11.976   11.999 12.083    
CCSD         11.978           11.875 11.734 11.995 12.087 12.031 12.115 12.134  
CCSD=FULL         11.976             11.733 11.983 12.096 12.029 12.093 12.141  
CCSD(T)   12.200     11.879   11.992   11.723   11.780 11.634 11.906 12.011 11.958 12.043 12.064 11.906
CCSD(T)=FULL         11.878           11.783 11.632 11.893 12.017 11.956 12.020 12.069  

Ionization Energies in eV
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 13.615 12.564 13.524 12.448 13.412 13.410
density functional LSDA 13.635 12.978 13.594 12.958 13.558 13.547
B1B95 13.356 12.607 13.161 12.441 13.027 13.013
B3LYP 13.553 12.802 13.478 12.758 13.379 13.362
Moller Plesset perturbation MP2 11.428 11.473 11.396 11.489 11.360 11.353
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.