National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 18October 2016
NIST Standard Reference Database 101
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XVII.C.1. (III.D.6.)

Calculated Ionization Energy for C2H3 (vinyl)

Experimental Ionization Energy is 8.25 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 AM1  
PM3  
PM6  
composite G2 8.360
G3 8.477
G4 8.469
CBS-Q 8.473

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
hartree fock HF 7.985 9.052 9.052 8.994 8.508 8.421 8.511 8.538 8.426 8.280 8.425 8.444 8.370 8.262 8.461 8.373 8.264
ROHF 6.738 8.053 8.053 7.985 7.966 7.943 8.050 8.056 8.023 7.893   8.013 8.009        
density functional LSDA 7.912 9.136 9.136 9.027 8.780 8.716 8.880 8.914 8.824 8.626   8.768 8.805   8.862    
SVWN   9.136     8.780   8.880       8.855            
BLYP 7.654 8.684 8.684 8.594 8.373 8.314 8.513 8.515 8.437 8.235   8.379 8.442        
B1B95 7.733 8.825 8.825 8.714 8.385 8.333 8.471 8.642 8.400 8.227   8.367 8.346   8.413    
B3LYP 7.905 8.975 8.975 8.877 8.612 8.546 8.710 8.724 8.637 8.451 8.675 8.599 8.627 8.660 8.690 8.642 8.668
B3LYPultrafine         8.612                        
B3PW91 7.972 9.071 9.071 8.937 8.660 8.588 8.713 8.738 8.644 8.487   8.621 8.616        
mPW1PW91 7.979 9.066 9.089 8.955 8.641 8.567 8.697 8.715 8.640 8.485   8.599 8.591        
M06-2X     8.455   8.455                        
PBEPBE 7.738 8.839 8.839 8.718 8.481 8.411 8.579 8.588 8.498 8.325   8.458 8.491   8.551    
PBE1PBE         8.613                        
HSEh1PBE   9.039     8.615   8.672           8.574        
TPSSh         8.640   8.700     8.471     8.610        
wB97X-D     8.976   8.553   8.609   8.532   8.551 8.609 8.485     8.495  
B97D3   8.896     8.517       8.534             8.542  
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
Moller Plesset perturbation MP2 6.308 8.102 8.102 8.002 7.781 7.793 7.949 7.932 7.904 7.775 7.899 7.920 8.008   8.040 8.041  
MP2=FULL 6.304 8.100     7.778 7.793 7.948 7.932 7.902     7.918          
MP3         7.968                        
MP3=FULL         7.965   8.144                    
MP4         7.885                        
B2PLYP         8.358               8.433        
Configuration interaction CID         8.071     8.204                  
CISD         8.145                        
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
Quadratic configuration interaction QCISD   8.600     8.236 8.263 8.392 8.373       8.396 8.445        
QCISD(T)         8.192                        
Coupled Cluster CCD         8.022     8.167       8.178          
CCSD         8.242                        
CCSD(T)         8.196             8.350 8.581   8.476 8.459  
CCSD(T)=FULL         8.186               8.402        
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

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 9.190 8.681 9.045 8.541 9.102 9.100
density functional B3LYP 9.081 8.797 9.056 8.772 9.032 9.027
Moller Plesset perturbation MP2 8.142 7.921 8.059 7.897 8.082 8.076
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.