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Computational Chemistry Comparison and Benchmark DataBase
Release 17bSeptember 2015
NIST Standard Reference Database 101
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XVII.C.1. (III.D.6.)

Calculated Ionization Energy for CN (Cyano radical)

Experimental Ionization Energy is 13.598 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 13.747
G3 13.875
G3B3 13.882
G4 13.755
CBS-Q 13.871

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
hartree fock HF 14.682 16.298 16.298 16.376 16.137 16.137 16.190 16.201 16.201 16.097 16.218 16.141 16.166 16.177 16.183 16.176 16.178 16.166
density functional LSDA 13.729 15.106 15.106 15.092 15.109 15.109 15.227 15.247 15.247 15.103   15.143 15.236   15.242     15.236
SVWN   15.106     15.109   15.227       15.253              
BLYP 13.130 14.416 14.416 14.424 14.445 14.445 14.597 14.577 14.577 14.457   14.484 14.595         14.595
B1B95 13.659 15.048 15.048 15.020 14.916 14.996 15.089 15.089 15.089 14.978   15.022 14.991     15.006   14.991
B3LYP 13.632 15.008 15.008 15.006 15.017 15.017 15.138 15.137 15.137 15.022 15.162 15.051 15.144 15.161 15.157 15.161 15.165 15.144
B3LYPultrafine         15.017                     15.161    
B3PW91 13.736 15.126 15.126 15.074 15.079 15.079 15.162 15.166 15.166 15.072   15.105 15.157         15.157
mPW1PW91 13.800 15.183 15.205 15.155 15.135 15.135 15.222 15.219 15.239 15.148   15.160 15.215         15.215
M06-2X     0.976   15.209                          
PBEPBE 13.306 14.593 14.593 14.568 14.579 14.579 14.701 14.679 14.679 14.579   14.614 14.689         14.689
PBE1PBE         15.104                          
HSEh1PBE   15.134     15.094               15.183          
TPSSh         14.906   14.991     14.897     14.994          
wB97X-D     15.228   15.160       15.234       15.207     15.221    
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
Moller Plesset perturbation MP2 9.707 11.941 11.941 11.865 12.541 12.541 12.648 12.696 12.696 12.763 12.711 12.597 12.880 12.963 12.756 12.925 12.977 12.880
MP2=FULL 9.701 11.936 11.936 11.859 12.556 12.556 12.662 12.707 12.707 12.801   12.600 12.931 13.015 12.760   13.031 12.931
MP3         14.417                          
MP3=FULL         14.433   14.522                      
MP4         11.986                          
B2PLYP         14.173               14.336          
Configuration interaction CID   13.762 13.762 13.739 14.218     14.385                    
CISD   13.783 13.783 13.814 14.201     14.338                    
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
Quadratic configuration interaction QCISD   13.153 13.153 13.204 13.700 13.700 13.787 13.802 13.802 13.921   13.747 14.026         14.026
QCISD(T)         13.418                          
Coupled Cluster CCD   13.098 13.098 13.061 13.661 13.661 13.751 13.838 13.838 13.919   13.698 14.067   13.849 14.112    
CCSD         13.893                          
CCSD(T)         13.311             13.357 13.632   13.511 13.682   13.632
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

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 16.454 16.119 16.357 16.158 16.357 16.349
density functional B3LYP 15.105 15.068 15.037 15.094 15.048 15.022
Moller Plesset perturbation MP2 11.760 12.479 11.750 12.537 11.720 11.703
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.