National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 22May 2022
NIST Standard Reference Database 101
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XVII.C.1. (III.D.6.)

Calculated Ionization Energy for C3H5 (Allyl radical)

Experimental Ionization Energy is 8.18 ± 0.07 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 8.194
G3 8.292
G3B3 8.227
G4 8.243
CBS-Q 8.323

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) 6-311+G(3df,2p) TZVP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
hartree fock HF 6.730 7.745 7.745 7.693 7.587 7.584 7.671 7.648 7.654 7.546   7.678 7.626 7.638 7.644 7.644 7.644
density functional LSDA 6.946 8.442 8.442 8.411 8.400 8.418 8.594 8.603 8.623 8.428   8.649 8.537 8.640 8.632 8.655  
BLYP 6.424 7.687 7.687 7.668 7.649 7.662 7.872 7.850 7.867 7.672   7.916 7.796 7.898      
B1B95 6.642 7.896 7.896 7.853 7.823 7.823 7.973 7.951 7.967 7.826   7.997 7.925 7.975   7.991  
B3LYP 6.716 7.966 7.966 7.934 7.905 7.915 8.088 8.072 8.087 7.915   8.126 8.029 8.107 8.116 8.127  
B3LYPultrafine         7.905                     8.127  
B3PW91 6.826 8.104 8.104 8.045 8.025 8.035 8.167 8.158 8.173 8.031   8.195 8.125 8.182      
mPW1PW91 6.849 8.120 8.120 8.061 8.038 8.046 8.182 8.165 8.179 8.040   8.207 8.136 8.189 8.188 8.205  
M06-2X 6.646 7.986 7.986 7.956 7.930 7.930 8.083 8.084 8.093 7.936 8.129 8.109 8.015 8.113 8.084 8.127  
PBEPBE 6.593 7.931 7.931 7.892 7.883 7.894 8.071 8.047 8.063 7.900   8.105 8.010 8.091 8.096 8.116  
PBE1PBE         8.015                        
HSEh1PBE 6.774 8.086 8.086 8.031 8.009 8.017 8.155 8.137 8.150 8.012   8.184 8.107 8.168 8.164 8.183  
TPSSh         7.914   8.058             8.073      
wB97X-D     8.020   7.929   8.075   8.081     8.102 8.075 8.072   8.084  
B97D3   7.873     7.803   7.977   7.972   8.022 8.012   7.999   8.023 8.024
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) TZVP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
Moller Plesset perturbation MP2 5.478 7.300 7.300 7.261 7.306 7.387 7.557 7.500 7.603 7.492   7.628 7.543 7.738 7.682 7.787  
MP2=FULL 5.476 7.300 7.300 7.261 7.312 7.393 7.563 7.509 7.612 7.505   7.636 7.548 7.756 7.687 7.805  
MP3         7.446                        
MP3=FULL         7.452   7.693                    
MP4   7.345     7.357       7.669         7.809      
B2PLYP         7.677                        
B2PLYP=FULLultrafine         7.678               7.838 7.956   7.988  
Configuration interaction CID   7.556 7.556 7.519 7.523     7.683                  
CISD   7.597 7.597 7.562 7.557     7.717                  
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) TZVP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
Quadratic configuration interaction QCISD   7.689 7.689 7.666 7.670 7.744 7.891 7.854 7.949 7.852   7.959 7.893 8.060 8.027    
QCISD(T)         7.594             7.902 7.823 8.034 7.979    
Coupled Cluster CCD   7.544 7.544 7.511 7.527 7.605 7.754 7.709 7.808 7.700   7.822 7.748 7.917 7.875    
CCSD         7.670               7.893 8.059      
CCSD(T)         7.592             7.899 7.820 8.017 7.976    
CCSD(T)=FULL         7.597             7.906 7.824 8.028 7.979    
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) TZVP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ

Ionization Energies in eV
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD cc-pVTZ-PP aug-cc-pVTZ-PP Def2TZVPP
hartree fock HF 7.703 7.577 7.786 7.639 7.809 7.813     7.649
density functional B3LYP 7.963 7.919 8.074 8.029 8.063 8.059     8.125
PBEPBE                 8.109
Moller Plesset perturbation MP2 7.305 7.341 7.394 7.437 7.403 7.402     7.761
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.