National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 17bSeptember 2015
NIST Standard Reference Database 101
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IIExperimental data
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XVEntropy data
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XVIIIon data
XVIIIBad calculations
XIXIndex of properties
XXH-bond dimers
XXIOddities

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XVII.C.1. (III.D.6.)

Calculated Ionization Energy for Cl2 (Chlorine diatomic)

Experimental Ionization Energy is 11.481 ± 0.003 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 11.520
G3 11.536
G3B3 11.533
G4 11.516
CBS-Q 11.543

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 aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z
hartree fock HF 11.129 12.163 11.261 12.014 11.186 11.186 11.180 11.234 11.234 10.898 11.134 11.164 10.890 11.080 10.885 10.843
density functional LSDA 11.348 11.938 11.938 12.294 11.894 11.894 11.924 12.016 12.016 11.738   11.854 11.801 11.884 11.803  
SVWN   12.387         11.924       11.919          
BLYP 10.603 11.566 11.178 11.507 11.148 11.148 11.212 11.303 11.303 10.995   11.095 11.063      
B1B95 11.420 11.502 11.502 11.918 11.424 11.424   11.494 11.494 11.250   11.395 11.267 11.386    
B3LYP 11.133 12.066 11.565 11.982 11.524 11.524 11.562 11.643 11.643 11.348 11.534 11.482 11.395 11.508 11.405 11.362
B3LYPultrafine         11.523                   11.404  
B3PW91 11.252 12.158 11.622 12.035 11.552 11.552 11.561 11.622 11.622 11.363   11.531 11.386      
mPW1PW91 11.295 12.164 11.629 12.071 11.529 11.560 11.572 11.628 11.628 11.364   11.537 11.384      
M06-2X     11.734   11.734                      
PBEPBE 10.799 11.756 11.321 11.671 11.278 11.278 11.315 11.388 11.388 11.111   11.237 11.152      
PBE1PBE         11.528                      
HSEh1PBE   12.142     11.516               11.345      
TPSSh         11.443   11.455     11.258     11.283      
wB97X-D     11.715   11.627       11.687       11.449   11.447  
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 aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z
Moller Plesset perturbation MP2   11.428 11.247 11.390 11.204 11.204 11.208 11.278 11.278 11.370 11.232 11.266 11.391 11.428 11.460  
MP2=FULL   11.425 11.245 11.387 11.201 11.201 11.205 11.267 11.267 11.367   11.265 11.381     11.363
MP3         11.235                      
MP3=FULL         11.230   11.232                  
MP4   11.578     11.161       11.225       11.363      
B2PLYP         11.380               11.338      
Configuration interaction CID   11.768 11.313 11.678 11.252     11.318                
CISD   11.740 11.293 11.656 11.231     11.298                
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 aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z
Quadratic configuration interaction QCISD   11.698 11.298 11.627 11.241 11.241 11.247 11.311 11.311 11.387   11.307 11.408      
QCISD(T)         11.178             11.233 11.365 11.403 11.442  
Coupled Cluster CCD   11.736 11.330 11.656 11.275 11.275 11.278 11.343 11.344 11.434   11.343 11.456 11.486 11.514  
CCSD         11.247                      
CCSD(T)                       11.238 11.370 11.408 11.447  
CCSD(T)=FULL         11.176                      
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 aug-cc-pVDZ aug-cc-pVTZ 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 12.012 11.143 11.959 11.110 12.340 12.098
density functional B3LYP 12.008 11.497 11.932 11.444 12.200 12.009
Moller Plesset perturbation MP2 11.405 11.283 11.390 11.268 11.541 11.334
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.