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 NO2 (Nitrogen dioxide)

Experimental Ionization Energy is 9.586 ± 0.002 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 PM3  
composite G2 9.690
G3 9.714
G3B3 9.613
G3MP2 9.722
G4 9.641
CBS-Q 9.755
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ daug-cc-pVTZ
hartree fock HF 8.889 10.521 10.521 10.844 9.718 9.718 9.781 9.600 9.600 9.370   9.629 9.544 9.443 9.449 9.630 9.471 9.463 9.466
ROHF   10.318 10.318 10.647 9.496 9.496 9.563 9.384 9.384     9.418 9.327 9.217 9.222 9.411 9.246 9.236  
density functional LSDA 8.564 10.191 10.191 10.573 10.000 10.000 10.235 10.001 10.001 9.797   10.079 9.840 9.940   10.134 10.018    
BLYP 8.252 9.734 9.734 10.106 9.540 9.540 9.827 9.553 9.553 9.338   9.683 9.384 9.519   9.738 9.628    
B1B95 8.612 10.080 10.080 10.362 9.456 9.640 9.809 9.594 9.594 9.394   9.681 9.487 9.319   9.510 9.381    
B3LYP 8.744 10.195 10.195 10.558 9.886 9.886 10.106 9.862 9.862 9.652   9.958 9.729 9.794 9.839 10.001 9.874 9.870  
B3LYPultrafine   10.195     9.886 9.886 10.106 9.862       9.958 9.729 9.794   10.001 9.874    
B3PW91 8.742 10.263 10.263 10.522 9.825 9.825 9.982 9.784 9.784 9.584   9.836 9.684 9.686   9.876 9.746    
mPW1PW91 8.791 10.267 10.303 10.556 9.799 9.799 9.960 9.751 9.782 9.585   9.847 9.658 9.656   9.885 9.754    
M06-2X 8.798 10.499 10.499 10.717 9.868 9.868 10.020 9.869 9.869 9.604 9.820 9.900 9.705 9.776   9.895 9.824    
PBEPBE 8.237 9.819 9.819 10.097 9.502 9.502 9.741 9.496 9.496 9.301   9.611 9.361 9.456   9.654 9.557    
PBEPBEultrafine   9.820     9.502 9.502 9.741 9.496       9.611 9.361 9.456   9.654 9.557    
PBE1PBE 8.671 10.225 10.225 10.488 9.761 9.761 9.926 9.715 9.715 9.522   9.793 9.619 9.635   9.822 9.704    
HSEh1PBE 8.664 10.207 10.207 10.479 9.756 9.756 9.922 9.713 9.712 9.514   9.793 9.610 9.633   9.817 9.701    
TPSSh 8.556 10.180 10.180 10.374 9.705 9.705 9.871 9.675 9.675 9.471   9.753 9.570 9.595 9.636 9.771 9.667 9.669  
wB97X-D 8.827 10.302 10.302 10.581 9.851 9.851 9.990 9.786 9.786 9.580   9.797 9.703 9.621 9.654 9.864 9.671 9.684  
B97D3 8.459 9.989 9.989 10.179 9.550 9.550 9.746 9.532 9.532 9.324 9.538 9.616 9.417 9.454 9.506 9.649 9.539 9.545 9.536
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ daug-cc-pVTZ
Moller Plesset perturbation MP2 5.642 8.435 8.435 8.886 8.771 8.771 8.968 8.657 8.657 8.621   8.786 8.553 8.731 8.665 8.952 8.861 8.762  
MP2=FULL 5.639 8.434 8.434 8.884 8.753 8.753 8.952 8.644 8.644 8.524   8.781 8.545 8.131 6.077 8.939 0.661 7.148  
ROMP2 5.858 8.749 8.749   8.986 8.986 9.186 8.870 8.870 8.909   8.997 8.764 9.059   9.177      
MP3             8.705         9.492 9.263 9.539          
MP3=FULL   9.908 9.908 10.346     9.514 9.402 9.402 9.365   9.495 9.268 9.478   9.612 9.592    
MP4                 8.658     8.776 8.582 8.884   9.037 9.051    
MP4=FULL         8.770       8.649       8.576 8.830   9.028      
B2PLYP 7.312 9.617 9.617 9.982 9.487 9.488 9.703 9.433 9.433 9.305   9.544 9.310 9.448   9.633 9.555    
B2PLYP=FULL 7.311 9.616 9.616 9.981 9.482 9.482 9.698 9.430 9.430 9.297   9.543 9.308 9.432   9.630 9.538    
B2PLYP=FULLultrafine 7.311 9.616 9.616 9.981 9.482 9.482 9.698 9.430 9.430 9.297   9.543 9.308 9.432   9.630 9.538    
Configuration interaction CID   9.723 9.723 10.124 9.438     9.343                      
CISD   9.738 9.738 10.137 9.381     9.336                      
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ daug-cc-pVTZ
Quadratic configuration interaction QCISD   9.644 9.644 10.028 9.455 9.455 9.632 9.328 9.314 9.331   9.445 9.222 9.463   9.604 9.596    
QCISD(T)         9.270     9.177       9.313 9.074 9.354   9.490 9.514    
QCISD(T)=FULL         9.289   9.492           9.065 9.295   9.479 9.450    
QCISD(TQ)         9.386   9.581           9.146 9.473          
QCISD(TQ)=FULL         9.365                            
Coupled Cluster CCD   9.553 9.553 9.977 9.297     9.188 9.188 9.275   9.130   9.420   9.379 9.541    
CCSD         9.471         9.331   9.439 9.224 9.471 9.578 9.545 9.602 9.636  
CCSD=FULL         9.444         9.299   9.428 9.212 9.410 9.563 9.473 9.537 9.620  
CCSD(T)         9.312 9.312 8.875 9.179 9.179     8.921 9.076 9.086   9.488 9.354    
CCSD(T)=FULL         9.292             9.308 9.067 9.233 9.349 9.478      
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ 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 11.213 9.965 11.078 9.876 10.912 10.907     9.460
density functional B3LYP 11.041 10.280 10.933 10.227 10.717 10.699     9.841
PBEPBE                 9.511
wB97X-D 10.902 10.091 10.798 10.035 10.627 10.612      
Moller Plesset perturbation MP2 9.045 9.003 9.038 9.017 8.844 8.841     8.740
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.