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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 PM6  
composite 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   12.291 12.172   12.131
density functional LSDA 10.881 13.408 13.408 13.497 12.858 12.858 13.016 12.877 12.877 12.683   12.701 12.789   12.907     12.789
BLYP 10.355 12.728 12.728 12.868 12.242 12.242 12.454 12.267 12.267 12.064   12.092 12.215         12.215
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   12.639 12.571   12.503
B3LYPultrafine         12.601                          
B3PW91 10.974 13.364 13.364 13.289 12.572 12.572 12.669 12.531 12.531 12.380   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   12.401 12.399         12.399
PBEPBE 10.417 12.856 12.856 12.895 12.244 12.244 12.410 12.241 12.241 12.075   12.107 12.188         12.188
Moller Plesset perturbation MP2FC 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   11.711 11.578
MP2FU   11.185     11.514 11.514 11.598 11.417 11.417     11.328 11.575 11.677 11.606     11.575
MP3         12.120                          
MP4         11.710                          
Configuration interaction CID         12.061     11.907                    
CISD         12.060                          
Quadratic configuration interaction QCISD   12.320     11.967 11.967 12.075 11.818 11.818       11.986         11.986
QCISD(T)         11.876                          
Coupled Cluster CCD         11.972     11.823                    
CCSD         11.978                          
CCSD(T)   12.200     11.879   11.992   11.723       11.906         11.906
CCSD(T)=FULL         11.878                     12.020    
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 B3LYP 13.553 12.802 13.478 12.758 13.379 13.362
Moller Plesset perturbation MP2FC 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.