National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 17bSeptember 2015
NIST Standard Reference Database 101
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III.D.6.a. (XVII.D.)

Calculated Electron Affininty for C2H (Ethynyl radical)

Experimental Electron Affinity is 2.923 ± 0.037 eV
Please note! These calculated electron affinity 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

Electron Affinities in eV
Methods with predefined basis sets
semi-empirical AM1  
PM3  
PM6  
composite G2 3.062
G3 2.970
G3B3 2.843
G4 2.853
CBS-Q 2.935

Electron Affinities 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) cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF -3.642 0.455 0.455 0.534 2.469 0.679 1.510 1.136 1.140 0.735 1.027 1.299 1.415 1.546 1.522 1.515
density functional LSDA -1.130 2.491 2.491 2.629 2.609 2.664 3.673 3.198 3.213 2.749 3.021 3.398   3.705 3.687  
BLYP -1.736 1.705 1.705 1.834 1.728 1.834 2.938 2.385 2.392 1.927 2.195 2.603        
B1B95 -1.601 1.901 1.901 2.019 2.075 2.039 2.924 2.430 2.504 2.109 2.377 2.661   2.971 2.974  
B3LYP -1.563 1.951 1.951 2.083 2.067 2.076 3.050 2.599 2.612 2.208   2.812 2.943 3.092 3.078 3.092
B3LYPultrafine         2.068                   3.098  
B3PW91 -1.583 1.997 1.997 2.098 2.106 2.133 2.996 2.582 2.588 2.185 2.455 2.740        
mPW1PW91 -1.646 1.978 1.956 2.053 2.102 2.115 2.973 2.554 2.537 2.139 2.433 2.708        
M06-2X     2.090                          
PBEPBE -1.671 1.871 1.871 1.932 1.976 1.982 2.981 2.473 2.473 2.056 2.322 2.661        
PBE1PBE         2.053                      
TPSSh         1.977   2.857     2.047   2.639        
wB97X-D     2.036   2.158       2.636     2.787     3.049  
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
Moller Plesset perturbation MP2 -2.190 1.782 1.782 2.076 2.260 2.290 3.277 2.813 2.838 2.595 2.775 3.224 3.444 3.559 3.581 3.616
MP2=FULL -2.189 1.785 1.785 2.079 2.252 2.281 3.267 2.814 2.838 2.574 2.773 3.193 3.423   3.547 3.592
MP3         2.064                      
MP3=FULL         2.055   2.999                  
MP4   1.651     2.203       2.784              
B2PLYP                       2.730        
Configuration interaction CID   1.353 1.353 1.589 1.843     2.362                
CISD   1.109 1.109 1.312 1.664     2.191                
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
Quadratic configuration interaction QCISD   0.980 0.980 1.180 1.588 1.614 2.554 2.147 2.177 1.932 2.073 2.549        
QCISD(T)         1.625           2.122 2.622   2.875    
Coupled Cluster CCD   1.465 1.465 1.729 2.020 2.048 2.961 2.564 2.588 2.353 2.530 2.944   3.241 3.244  
CCSD         1.582                      
CCSD(T)                     2.126 2.642   2.866 2.985  
CCSD(T)=FULL         1.627                      
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ

Electron Affinities in eV
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 1.092 1.261 1.156 1.318 1.046 1.051
density functional B3LYP 2.777 2.903 2.746 2.693 2.639 2.643
Moller Plesset perturbation MP2 2.852 3.043 2.905 3.014 2.708 2.722
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.