National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 22May 2022
NIST Standard Reference Database 101
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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 S2 (Sulfur diatomic)

Experimental Ionization Energy is 9.356 ± 0.002 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 PM3  
composite G2 9.288
G3 9.389
G3B3 9.362
G4 9.349
CBS-Q 9.434

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(D+d)Z cc-pV(T+d)Z aug-cc-pV(T+d)Z daug-cc-pVTZ
hartree fock HF 6.590 10.434 9.478 10.331 9.466 9.466 9.454 9.410 9.410 9.278   9.377 9.391 9.274 9.251 9.407 9.288 9.256 9.306 9.231 9.245 9.287
density functional LSDA 6.914 3.381 10.054 10.503 10.038 10.038 10.051 10.024 10.024 9.925     9.992 9.956   10.032            
BLYP 6.241 9.893 9.348 9.809 9.362 9.362 9.399 9.383 9.384 9.253     9.292 9.282           9.255    
B1B95 6.717   9.580 10.125 9.540 9.556 9.563 9.534 9.534 9.427     9.512 9.418 9.414 9.530 9.443 9.420   9.433 9.445  
B3LYP 6.686 10.310 9.678 10.215 9.681 9.681 9.700 9.674 9.674 9.552   9.649 9.616 9.571 9.554 9.665 9.583 9.560   9.539 9.552  
B3LYPultrafine         9.681                       9.584          
B3PW91 6.818 10.425 9.782 10.288 9.746 9.746 9.745 9.714 9.714 9.615     9.712 9.624           9.593    
mPW1PW91 6.854 10.429 9.795 10.326 9.733 9.733 9.734 9.708 9.737 9.628     9.694 9.607           9.605    
M06-2X     9.716   9.706           9.537                 9.525    
PBEPBE 6.443 10.105 9.546 9.997 9.537 9.537 9.555 9.541 9.541 9.427     9.485 9.444           9.417    
PBE1PBE         9.738                                  
HSEh1PBE   10.411     9.727   9.683             9.604           9.572    
TPSSh         9.675   9.676     9.550       9.561                
wB97X-D     9.763   9.730   9.728   9.685     9.675 10.889 9.585     9.589          
B97D3   10.152     9.542   9.559   9.546   9.440 9.514   9.447     9.460         9.460
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(D+d)Z cc-pV(T+d)Z aug-cc-pV(T+d)Z daug-cc-pVTZ
Moller Plesset perturbation MP2 4.620   8.948 8.881 8.931 8.930 8.931 8.911 8.911 9.202   8.964 9.025 9.220 9.280 9.196 9.274 9.303   9.204 9.259  
MP2=FULL     8.938 8.873 8.920 8.920 8.920 8.904 8.904 9.191     9.018 9.206 9.269     9.291 8.987 9.189 9.239  
MP3         9.072                                  
MP3=FULL         9.063   9.061                              
MP4   9.288     8.906       8.877         9.234           9.215    
B2PLYP         9.358                 9.382                
B2PLYP=FULLultrafine         9.355               9.344 9.378     9.405          
Configuration interaction CID   9.694 9.152 9.582 9.137     9.106                       9.325    
CISD   9.683 9.141 9.578 9.126     9.098                       9.319    
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(D+d)Z cc-pV(T+d)Z aug-cc-pV(T+d)Z daug-cc-pVTZ
Quadratic configuration interaction QCISD   9.506 9.038 9.418 9.028 9.028 9.030 9.007 9.007 9.318     9.110 9.342           9.316    
QCISD(T)         8.938               9.012 9.272   9.217 9.343     9.250    
Coupled Cluster CCD   9.535 9.059 9.435 9.047 9.047 9.046 9.021 9.021 9.328     9.131 9.353   9.299 9.405     9.325 9.378  
CCSD         9.035                                  
CCSD(T)                         9.017 9.277   9.221 9.347     9.254    
CCSD(T)=FULL         8.933                             9.240    
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(D+d)Z cc-pV(T+d)Z aug-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 10.384 9.473 10.335 9.428 10.517 10.373     9.220
density functional B3LYP 10.267 9.701 10.200 9.645 10.399 10.276     9.525
PBEPBE                 9.405
Moller Plesset perturbation MP2 8.910 9.053 8.895 9.032         9.195
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.