National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 22May 2022
NIST Standard Reference Database 101
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III.D.6.a. (XVII.D.)

Calculated Electron Affininty for C2 (Carbon diatomic)

Experimental Electron Affinity is 3.273 ± 0.008 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 PM3  
composite G2 3.100
G3 3.155
G3B3 3.164
G4 3.177
CBS-Q 3.172
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) 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 -0.620 3.740 3.740 3.801 3.764 3.771 4.488 4.218 4.218 3.812   4.466 4.074 4.355 4.459 4.521 4.539 4.541 4.355 4.539
density functional LSDA -0.394 3.567 3.567 3.629 3.790 3.624 4.542 4.201 4.201 3.696     3.969 4.351   4.582     4.351  
BLYP -0.991 2.852 2.852 2.916 2.917 2.917 3.933 3.482 3.482 3.007     3.263 3.672         3.672  
B1B95 -0.697 3.204 3.204 3.233 3.319 3.215 4.019 3.693 3.693 3.269     3.533 3.933   4.161 4.156   3.933  
B3LYP -0.541 3.367 3.367 3.423 3.415 3.415 4.319 3.949 3.949 3.490   4.257 3.748 4.116 4.238 4.352 4.365 4.367 4.116  
B3LYPultrafine         3.415                       4.366      
B3PW91 -0.453 3.517 3.517 3.535 3.521 3.521 4.299 4.008 4.008 3.576     3.835 4.138         4.138  
mPW1PW91 -0.409 3.596 3.575 3.590 3.595 3.595 4.371 4.068 4.049 3.625     3.904 4.197         4.197  
M06-2X     3.476   3.451           4.327                  
PBEPBE -0.836 3.079 3.079 3.113 3.723 3.723 6.738 6.369 6.369 6.010     6.069 6.518         3.779  
PBE1PBE         3.529                              
HSEh1PBE   2.718     3.512   4.417             3.173            
TPSSh         3.390   4.175     3.437       3.997            
wB97X-D     3.592   3.588   4.391   4.083     4.346 4.391 4.202     4.417      
B97D3   3.084     4.347   5.091   4.778   5.153 5.070   3.760     5.147     4.021
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 -2.801 1.744 1.744 1.867 2.101 2.101 2.981 2.660 2.660 2.382   2.910 2.539 2.982 3.154 3.213 3.270 3.292 2.982  
MP2=FULL -2.806 1.741 1.741 1.863 2.103 2.103 2.983 2.662 2.663 2.384     2.538 2.985 3.163 3.210   3.300 2.985  
MP3         2.959                              
MP3=FULL         2.966   3.787                          
MP4   1.307     1.754       2.307         2.671            
B2PLYP         2.757                 3.506            
B2PLYP=FULLultrafine         2.758               3.119 3.507     3.772      
Configuration interaction CID   2.381 2.381 2.504 2.815     3.371                        
CISD   2.212 2.212 2.335 2.688     3.245                        
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   1.586 1.586 1.725 2.166 2.166 3.029 2.747 2.747 2.518     2.601 3.126         3.126  
QCISD(T)         1.899               2.351 2.876   3.068 3.179      
Coupled Cluster CCD   1.934 1.934 2.074 2.454 2.454 3.285 3.035 3.035 2.803     2.895 3.406   3.537 3.662      
CCSD         2.247                              
CCSD(T)   1.281     1.908   2.815   2.491       2.362 2.895 3.087 3.082 3.200 3.227 2.895  
CCSD(T)=FULL         1.911                   3.096     3.235    
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
Electron Affinities 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 4.236 4.195 4.328 4.329 4.259 4.265     4.470
density functional B3LYP 3.992 3.970 4.085 4.085 3.973 3.965     4.257
PBEPBE                 5.312
Moller Plesset perturbation MP2 2.486 2.712 2.563 2.776 2.417 2.419     3.119
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.