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 NH3 (Ammonia)

Experimental Ionization Energy is 10.07 ± 0.02 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  
composite G2 10.137
G3 10.085
G3B3 10.104
G3MP2 10.102
G4 10.117
CBS-Q 10.115

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 cc-pV(T+d)Z daug-cc-pVTZ
hartree fock HF 6.632 8.000 8.000 8.302 8.411 8.401 8.544 8.439 8.446 8.441   8.507 8.384 8.508 8.549 8.571 8.570 8.572 8.508 8.569
density functional LSDA 8.485 9.919 9.919 10.358 10.553 10.579 10.848 10.686 10.724 10.648   10.836 10.575 10.845   10.925 10.959   10.845  
BLYP 7.966 9.128 9.129 9.486 9.720 9.740 10.032 9.837 9.874 9.785   10.003 9.741 9.988     10.120   9.988  
B1B95 8.034 9.234 9.234 9.596 9.786 10.066 10.026 9.891 9.906 9.853   9.973 9.809 9.978   10.060 10.071      
B3LYP 8.077 9.291 9.291 9.648 9.848 9.860 10.108 9.946 9.976 9.908   10.085 9.856 10.079 10.145 10.167 10.187 10.191 10.079  
B3LYPultrafine   9.291     9.848 9.860 10.108 9.946       10.085 9.856 10.079   10.167 10.188      
B3PW91 8.083 9.303 9.303 9.637 9.825 9.837 10.044 9.908 9.936 9.889   10.017 9.836 10.023         10.023  
mPW1PW91 8.021 9.240 9.258 9.584 9.749 9.757 9.966 9.825 9.867 9.826   9.949 9.760 9.938   10.035 10.045   9.938  
M06-2X 8.097 9.377 9.377 9.693 9.891 9.885 10.082 9.981 10.002 9.954 10.197 10.089 9.890 10.117   10.140 10.199      
PBEPBE 8.025 9.235 9.234 9.577 9.805 9.821 10.081 9.900 9.938 9.878   10.049 9.832 10.046   10.150 10.166   10.046  
PBEPBEultrafine   9.235     9.805 9.821 10.081 9.900       10.049 9.832 10.046   10.150 10.166      
PBE1PBE 7.955 9.220 9.220 9.554 9.740 10.013 9.957 9.812 9.840 9.802   9.929 9.749 9.933   10.014 10.027      
HSEh1PBE 7.950   9.212 9.544 9.729 9.737   9.804 9.832 9.790   9.924 9.737     10.005 10.019      
TPSSh   9.175 9.175 9.471 9.662 9.670 9.879 9.741   9.712   9.848 9.661 9.846   9.922 9.940      
wB97X-D     9.310   9.847   10.063   9.940     10.007 9.812 10.011     10.096      
B97D3   9.254     9.812   10.067   9.924   10.141 10.018   10.014     10.122     10.121
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 cc-pV(T+d)Z daug-cc-pVTZ
Moller Plesset perturbation MP2 6.927 8.646 8.646 9.067 9.484 9.600 9.830 9.549 9.743 9.850   9.834 9.623 10.056 10.202 10.032 10.206 10.264 10.056  
MP2=FULL 6.927 8.648 8.648 9.069 9.487 9.605 9.835 9.555 9.749 9.856   9.839 9.628 10.059 10.211 10.037 10.212 10.273 10.059  
MP3         9.372   9.711         9.695 9.522 9.912            
MP3=FULL         9.374   9.697         9.698 9.525 9.913            
MP4   8.620     9.416       9.694     9.782 9.568 10.009   9.981 10.157      
MP4=FULL   8.621     9.418       9.698       9.572 10.010   9.984 10.162      
B2PLYP 7.630 9.018 9.018 9.392 9.653 9.693 9.933 9.735 9.814 9.805   9.919 9.699 9.982   10.042 10.105      
B2PLYP=FULL 7.630 9.018 9.018 9.393 9.654 9.695 9.935 9.737 9.815 9.807   9.920 9.701 9.983   10.043 10.107      
B2PLYP=FULLultrafine         9.654               9.701 9.983     10.107      
Configuration interaction CID   8.520 8.520 8.902 9.276     9.330                        
CISD     8.519 8.897 9.277     9.334                        
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 cc-pV(T+d)Z daug-cc-pVTZ
Quadratic configuration interaction QCISD   8.566 8.566 8.956 9.368 9.478 9.684 9.430 9.606 9.713   9.686 9.500 9.885   9.876 10.014      
QCISD(T)         9.390             9.744 9.542 9.966   9.946 10.109      
QCISD(T)=FULL         9.392   9.730           9.545 9.967 10.108 9.948 10.113 10.162    
QCISD(TQ)         9.390   9.725           9.542 9.958   9.942 10.098      
QCISD(TQ)=FULL         9.393   9.729           9.546 9.959   9.945 10.103      
Coupled Cluster CCD   8.567 8.567 8.960 9.365 9.478 9.677 9.424 9.603 9.714   9.678 9.499 9.881   9.865 10.007      
CCSD         9.364         9.711   9.680 9.498 9.880 10.001 9.870 10.008 10.050    
CCSD=FULL         9.366         9.716   9.684 9.501 9.882 10.009 9.873 10.013      
CCSD(T)         9.388             9.741 9.541 9.964 10.098 9.943 10.106      
CCSD(T)=FULL         9.391             9.745 9.544 9.965 10.106 9.946 10.111 10.160    
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 cc-pV(T+d)Z 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 8.306 8.417 8.362 8.463 8.385 8.387     8.542
density functional B3LYP 9.623 9.789 9.709 9.874 9.768 9.765     10.134
PBEPBE                 10.102
Moller Plesset perturbation MP2 9.118 9.533 9.239 9.626 9.224 9.228     10.110
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.