return to home page

XVII.C.1.

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 6-31G* 6-31+G** TZVP cc-pVTZ
hartree fock HF       8.846  
density functional SVWN 10.485 10.244 10.434    
B3LYP       9.844  
M06-2X   9.840      
PBE1PBE   9.610      
HSEh1PBE   9.590      
TPSSh     9.630    
Moller Plesset perturbation MP2       10.410  
MP3=FULL   9.699 9.880    
B2PLYP   9.636     9.961
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.