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XVII.C.1.

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
G4 15.577
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) TZVP 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 15.635 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    
SVWN   15.698     16.007 16.007 16.122 16.100 16.100 15.968   15.899 16.093   16.097 16.137        
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 14.428 15.523 15.523 15.694 15.654 15.729 15.809 15.771 15.771 15.680 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 15.610 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 15.519 15.543 15.674 15.702 15.702 15.776 15.746 15.767 15.680 15.801 15.616 15.730   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 15.150 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 15.469 15.469 15.613 15.661 15.661 15.738 15.709 15.709 15.621 15.747 15.571 15.701   15.716 15.738        
TPSSh         15.451   15.525           15.495              
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 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                          
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   15.388 15.388 15.367 15.438 15.234 15.457   15.445 15.518        
Configuration interaction CID   14.816 14.816 15.060 15.483     15.531                        
CISD     14.705 14.954 15.389     15.438                        
Quadratic configuration interaction QCISD   14.445 14.445 14.708 15.217 15.217 15.294 15.266 15.266 15.420 15.288 15.118 15.498   15.349 15.573   15.498    
QCISD(T)         15.099           15.163 14.998 15.377   15.249 15.461        
QCISD(T)=FULL         15.714   15.738         15.635 15.691 15.692 15.714 15.707 15.700   15.645 15.694
Coupled Cluster CCD   14.639 14.639 14.897 15.385 15.385 15.455 15.435 15.435 15.587 15.449 15.288 15.666   15.515 15.737        
CCSD         15.270           15.340 15.171 15.550 15.660 15.402 15.624 15.690      
CCSD=FULL         15.276           15.351 15.176 15.574 15.689 15.408 15.650 15.719      
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      

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 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.