return to home page Computational Chemistry Comparison and Benchmark DataBase Release 19 (April 2018) Standard Reference Database 101 National Institute of Standards and Technology
You are here: Home > Ions > Energy > Calculated Ionization Energy OR Calculated > Energy > Ion > Calculated Ionization Energy

Calculated Ionization Energy for C4H2 (Diacetylene)

Experimental Ionization Energy is 10.17 ± 0.02 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 G4 10.205

Ionization Energies in eV
Methods with standard basis sets
3-21G 3-21G* 6-31G* 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) TZVP Def2TZVPP cc-pVDZ cc-pVTZ aug-cc-pVTZ
hartree fock HF                 8.846 8.807      
density functional BLYP     9.272                    
B3LYP                 9.844 9.832      
B3LYPultrafine                         9.838
M06-2X   10.091 9.840                    
PBEPBE                   9.740      
PBE1PBE     9.610                    
HSEh1PBE 9.882   9.590 9.752               9.803  
TPSSh     9.469 9.630     9.481         9.683  
wB97X-D   9.976 9.661 9.821   9.889     9.884   9.821 9.858 9.864
B97D3 9.666   9.388 9.576   9.618   9.640       9.615 9.630
3-21G 3-21G* 6-31G* 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) TZVP Def2TZVPP cc-pVDZ cc-pVTZ aug-cc-pVTZ
Moller Plesset perturbation MP2     10.147   10.393       10.410 10.634      
MP3=FULL     9.699 9.880                  
B2PLYP     9.636                 9.961  
Coupled Cluster CCSD(T)=FULL     9.625                    
3-21G 3-21G* 6-31G* 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) TZVP Def2TZVPP cc-pVDZ cc-pVTZ aug-cc-pVTZ
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.