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Calculated Ionization Energy for C2H4 (Ethylene)

Experimental Ionization Energy is 10.5138 ± 0.0006 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
composite G2 10.533
G3 10.516
G3MP2 10.557
CBS-Q 10.537

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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF 7.382 8.896 8.896 8.739 8.647 8.643 8.747 8.726 8.733 8.611 8.770 8.750 8.702 8.738 8.749 8.720 8.746 8.751
density functional BLYP 8.894 10.102 10.102 10.008 9.956 9.973 10.155 10.168 10.190 9.985     10.091 10.224        
B1B95 9.117 10.280 10.280 10.160 10.105 10.130 10.251 10.431 10.268 10.134     10.212 10.264   10.188    
B3LYP 9.020 10.262 10.262 10.151 10.057 10.106 10.258 10.272 10.292 10.112     10.207 10.281   10.285 10.333  
B3LYPultrafine         10.093                          
B3PW91 9.092 10.332 10.332 10.190 10.130 10.143 10.256 10.270 10.288 10.140     10.218 10.301        
mPW1PW91 9.036 10.266 10.289 10.145 10.058 10.069 10.188 10.192 10.232 10.087     10.146 10.225        
M06-2X     10.228                              
PBEPBE 9.083 10.310 10.310 10.199 10.142 10.156 10.306 10.310 10.330 10.160     10.257 10.358        
wB97X-D                                 10.205  
B97D3                                 10.200  
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
Moller Plesset perturbation MP2 8.243 9.939 9.939 9.843 9.935 10.025 10.167 10.140 10.246 10.205     10.165 10.419   10.306 10.494  
MP2=FULL 8.245 9.935 9.935 9.842 9.958 10.039 10.179 10.154 10.259 10.226     10.175 10.466   10.316 10.523  
MP3         9.803   10.046                      
MP3=FULL         9.814   10.022                      
MP4   9.983     9.955       10.237                  
Configuration interaction CID   9.743 9.743 9.621 9.625     9.769                    
CISD     9.766 9.647 9.642     9.785                    
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
Quadratic configuration interaction QCISD   9.951 9.951 9.845 9.869 9.939 10.055 10.023 10.113 10.065     10.045 10.250        
QCISD(T)         9.966               10.154 10.403        
Coupled Cluster CCD   9.915 9.915 9.806 9.821 9.897 10.011 9.978 10.072 10.029     10.008 10.218   10.122    
CCSD(T)         9.962               10.151 10.400   10.282 10.450  
CCSD(T)=FULL         9.974                 10.420   10.284    
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP Def2TZVPP 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)
daug-cc-pVDZ daug-cc-pVTZ daug-cc-pVQZ Sadlej_pVTZ CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF         8.620 8.520 8.759 8.682 8.819 8.823
density functional B3LYP         9.950 9.884 10.112 10.067 10.218 10.212
Moller Plesset perturbation MP2         9.687 9.813 9.899 10.017 9.938 9.944
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.