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Calculated Ionization Energy for N2 (Nitrogen diatomic)

Experimental Ionization Energy is 15.581 ± 0.008 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 15.553
G3 15.552
G3B3 15.579
G4 15.576
CBS-Q 15.549

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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ
hartree fock HF 13.961 15.545 15.545 15.721 15.714 15.714 15.736 15.737 15.737 15.658   15.742 15.702 15.635 15.688 15.689 15.716 15.705 15.697 15.688    
density functional LSDA 14.616 15.698 15.698 15.916 16.007 16.007 16.122 16.100 16.100 15.968   16.132   15.899 16.093   16.097 16.137   16.093    
BLYP 13.863 14.855 14.855 15.095 15.183 15.183 15.333 15.259 15.259 15.151   15.337   15.069 15.281         15.281    
B1B95 14.375 15.435 15.435 15.693 15.654 15.654 15.730 15.692 15.692 15.679   15.725   15.633 15.675   15.709 15.712        
B3LYP 14.336 15.428 15.428 15.641 15.714 15.714 15.823 15.779 15.779 15.677   15.832 15.813 15.610 15.784 15.804 15.802 15.831 15.826 15.784    
B3LYPultrafine         15.714             15.832   15.610 15.784   15.802 15.831        
B3PW91 14.395 15.505 15.505 15.642 15.700 15.700 15.770 15.746 15.746 15.655   15.769   15.611 15.728         15.728    
mPW1PW91 14.415 15.543 15.543 15.674 15.724 15.724 15.797 15.767 15.767 15.680   15.801   15.638 15.751   15.776 15.787   15.730    
M06-2X 14.627 15.796 15.796 15.988 16.033 16.033 16.109 16.102 16.102 15.993   16.091   15.937 16.087   16.090 16.118        
PBEPBE 14.003 14.998 14.998 15.178 15.246 15.246 15.366 15.303 15.303 15.216   15.367 15.347 15.150 15.314   15.348 15.371   15.314    
PBEPBEultrafine         15.246             15.367   15.150 15.314   15.348 15.371        
PBE1PBE 14.345 15.474 15.474 15.624 15.671 15.671 15.748 15.714 15.714 15.633   15.752   15.585 15.705   15.729 15.742        
HSEh1PBE 14.327 15.604 15.469 15.613 15.661 15.661 15.886 15.709 15.709 15.621   15.747   15.571 15.848   15.716 15.738        
TPSSh   15.275 15.275 15.395 15.451 15.451 15.525 15.503   15.406   15.543   15.366 15.496   15.501 15.534        
wB97X-D     15.679   15.848   15.911   15.877     15.890   16.060 15.832     15.862        
B97D3   15.096     15.268   15.368   15.321   15.379       15.325     15.374        
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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ
Moller Plesset perturbation MP2 12.606 14.222 14.222 14.505 14.964 14.964 15.058 15.010 15.010 15.146   15.039 15.253 14.867 15.224 15.336 15.121 15.308 15.375 15.224 14.881 15.233
MP2=FULL 12.605 14.222 14.222 14.505 14.970 14.970 15.065 15.021 15.021 15.160   15.049   14.872 15.247 15.364 15.126 15.333 15.403 15.247 14.887 15.258
MP3         15.619   15.768         15.675   15.521 15.872              
MP3=FULL         15.625   15.687         15.685   15.526 15.893              
MP4   14.069     14.878       14.906     14.935   14.781 15.148   15.043 15.236        
MP4=FULL   14.068     14.884       14.916         14.785 15.171   15.047 15.263        
B2PLYP 13.598 14.892 14.892 15.128 15.335 15.335 15.439 15.388 15.388 15.367   15.438   15.234 15.457   15.445 15.518        
B2PLYP=FULL 13.598 14.892 14.892 15.128 15.337 15.337 15.441 15.391 15.391 15.371   15.440   15.236 15.463   15.447 15.525        
Configuration interaction CID   14.816 14.816 15.060 15.483     15.531                            
CISD   14.705 14.705 14.954 15.389     15.438                            
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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ
Quadratic configuration interaction QCISD   14.186 14.399 14.630 14.820 15.217 15.284 14.769 15.266 15.417   15.288   15.108 15.444   15.323 15.574   15.498    
QCISD(T)         15.099             15.163   14.998 15.377   15.249 15.461        
QCISD(T)=FULL         15.104   15.189             15.003 15.398 15.514 15.254 15.484 15.548   15.023 15.409
Coupled Cluster CCD   14.603 14.603 14.833 14.943 15.368 15.439 14.884 15.434 15.586   15.450   15.288 15.667   15.497 15.738        
CCSD         14.856             15.340   15.151 15.551 15.660 15.379 15.625 15.690      
CCSD=FULL         15.256             15.352   15.157 15.574 15.688 15.386 15.650 15.724      
CCSD(T)   14.382     15.124   15.208   15.164     15.189   15.023 15.404 15.518 15.274 15.488 15.551 15.404    
CCSD(T)=FULL         15.129             15.198   15.028 15.425 15.541 15.279 15.511 15.575      
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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ

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         15.564 15.554 15.516 15.626 15.523 15.520
density functional B3LYP         15.523 15.585 15.520 15.656 15.519 15.499
Moller Plesset perturbation MP2         14.357 14.848 14.445 14.939 14.331 14.336
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.