National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 18October 2016
NIST Standard Reference Database 101
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XIXIndex of properties
XXH-bond dimers
XXIOddities

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XVII.C.1. (III.D.6.)

Calculated Ionization Energy for CH3 (Methyl radical)

Experimental Ionization Energy is 9.84 ± 0.01 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 G3 9.945
G3B3 9.905
G4 9.901
CBS-Q 9.899

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 cc-pV(T+d)Z cc-pCVTZ
hartree fock HF 8.089 9.132 9.132 9.054 9.010 8.998 9.044 9.027 9.026 8.995 9.038 8.997 9.039 9.048 9.024 9.044   9.039 9.041
ROHF   9.054 9.054 9.054 8.900 8.885 9.112 8.912 9.026   9.038 8.887 8.927 9.048 9.024 9.044 9.049    
density functional LSDA 9.201 10.380 10.380 10.356 10.355 10.366 10.495 10.487 10.501 10.374 10.527 10.417 10.527   10.511 10.543   10.527 10.530
SVWN   10.380     10.355 10.366 10.495 10.487 10.501 10.374 10.527 10.417 10.527   10.511 10.543     10.530
BLYP 8.694 9.646 9.646 9.633 9.623 9.630 9.782 9.763 9.774 9.640 9.811 9.702 9.809           9.812
B1B95 8.770 9.723 9.723 9.689 9.673 9.670 9.770 9.886 9.756 9.674 9.785 9.702 9.780   9.777 9.793   9.786 9.783
B3LYP 8.872 9.834 9.834 9.805 9.788 9.791 9.910 9.894 9.905 9.798 9.932 9.845 9.932 9.947 9.928 9.946 9.952 9.932 9.935
B3LYPultrafine   9.834     9.788 9.791 9.910 9.894     9.932 9.844     9.928 9.946     9.935
B3PW91 9.001 9.969 9.969 9.913 9.906 9.909 9.998 9.979 9.987 9.915 10.010 9.937 10.012           10.015
mPW1PW91 8.995 9.945 9.962 9.904 9.880 9.881 9.973 9.949 9.973 9.903 10.001 9.912 9.985   9.985 10.014     10.004
M06-2X 8.751 9.736 15.629 9.693 9.670 9.663 9.763 9.769 9.771 9.672 9.782 9.677 9.792   9.754 9.803     9.797
PBEPBE 8.892 9.893 9.893 9.865 9.867 9.870 9.999 9.971 9.980 9.881 10.016 9.925 10.017   10.012 10.036   10.017 10.019
PBEPBEultrafine   9.893     9.867 9.870 9.999 9.971     10.016 9.925 10.017   10.012 10.036     10.019
PBE1PBE 8.965 9.932 9.932 9.884 9.876 9.876 9.968 9.944 9.951 9.882 9.978 9.908 9.981   9.968 9.992     9.983
HSEh1PBE 8.960 9.928 9.928 9.876 9.868 9.868   9.938 9.945 9.875 9.973 9.901 9.976   9.961 9.987     9.979
TPSSh   9.890 9.890 9.833 9.813 9.814 9.903 9.879   9.819 9.914 9.839 9.919   9.895 9.932     9.922
wB97X-D     9.788   9.692   9.788   9.769   9.794 9.788 9.784     9.798      
B97D3   9.786     9.725       9.816             9.874      
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 cc-pV(T+d)Z cc-pCVTZ
Moller Plesset perturbation MP2 7.959 9.357 9.357 9.325 9.397 9.470 9.553 9.507 9.604 9.589 9.597 9.547 9.737 9.783 9.656 9.770 9.797 9.737 9.739
MP2=FULL 8.013 9.358 9.358 9.326 9.403 9.477 9.560 9.515 9.612 9.599 9.605 9.552 9.753 9.801 9.661 9.786 9.815   9.752
MP3         9.376   9.452       9.577 9.538 9.724           9.726
MP3=FULL         9.382   9.540       9.585 9.542 9.740           9.739
MP4   9.357     9.391       9.603   9.596 9.542 9.749   9.669 9.786     9.752
MP4=FULL   9.358     9.397       9.611     9.546 9.766   9.674 9.802     9.766
B2PLYP 8.543 9.611 9.611 9.580 9.587 9.610 9.714 9.688 9.725 9.653 9.741 9.670 9.787   9.761 9.807     9.790
B2PLYP=FULL 8.543 9.611 9.611 9.580 9.588 9.613 9.715 9.691 9.727 9.656 9.744 9.671 9.792   9.762 9.812     9.794
Configuration interaction CID   9.345 9.345 9.310 9.348     9.446         9.638           9.640
CISD     9.352 9.317 9.359     9.458         9.651           9.652
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 cc-pV(T+d)Z cc-pCVTZ
Quadratic configuration interaction QCISD   9.375 14.935 9.343 9.392 9.454 9.534 9.497 9.581 9.571 9.573 9.527 9.705   9.641 9.738     9.707
QCISD(T)         9.404           9.602 9.547 9.750   9.675 9.788     9.752
QCISD(T)=FULL         9.410   9.562         9.551 9.766 9.818 9.679 9.804 9.830   9.766
QCISD(TQ)         9.404   9.556         9.549   9.799 9.678 9.788      
QCISD(TQ)=FULL         9.410   9.563         9.554 9.767 9.818 9.682 9.804      
Coupled Cluster CCD   9.366 9.366 9.335 9.378 9.443 9.520 9.482 9.568 9.555 9.558 9.515 9.689   9.625       9.690
CCSD         9.389             9.525 9.703 9.745 9.639 9.735     9.705
CCSD=FULL         9.395               9.719 9.764 9.644 9.752     9.719
CCSD(T)         9.403   9.554       9.601 9.547 9.750 9.798 9.674 9.787 9.811 9.750 9.752
CCSD(T)=FULL         9.409           9.609 9.551 9.766 9.817 9.679 9.803 9.829   9.766
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 cc-pV(T+d)Z cc-pCVTZ

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 8.982 8.926 9.055 8.984 9.105 9.107
density functional B3LYP 9.755 9.729 9.843 9.811 9.903 9.896
Moller Plesset perturbation MP2 9.268 9.338 9.353 9.412 9.408 9.409
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.