National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 22May 2022
NIST Standard Reference Database 101
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XVII.C.1. (III.D.6.)

Calculated Ionization Energy for C2Cl2 (dichloroacetylene)

Experimental Ionization Energy is 9.9 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
composite G2 10.020
G3 10.006
G4 10.021
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 aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
hartree fock HF 8.883 10.060 9.570 9.836 9.226 9.226 9.266 9.263 9.263 9.048   9.304 9.226 9.129 9.211 9.130 9.127
density functional LSDA 9.534 10.597 10.262 10.436 10.089 10.089 10.186 10.249 10.249       10.144 10.194 10.222    
BLYP 8.737 9.764 9.434 9.620 9.272 9.272 9.410 9.459 9.459 9.215     9.320 9.387      
B1B95 9.151   9.873 10.126 9.639 9.672 9.747 9.780 9.780 9.589     9.716 9.662      
B3LYP 9.239 10.228 9.849 10.069 9.656 9.656 9.760 9.804 9.804 9.579   9.805 9.700 9.726 9.778 9.739  
B3LYPultrafine         9.656                     9.739  
B3PW91 9.351 10.327 9.944 10.132 9.712 9.712 9.776 9.805 9.805 9.627     9.760 9.733      
mPW1PW91 9.387 10.313 9.962 10.117 9.680 9.680 9.746 9.768 9.812 9.633     9.723 9.691      
M06-2X     10.201   9.988           10.003            
PBEPBE 8.937 9.965 9.628 9.798 9.441 9.441 9.543 9.574 9.574 9.378     9.487 9.510      
PBE1PBE         9.700                        
HSEh1PBE   10.304     9.679   9.749             9.701      
TPSSh         9.569   9.637     9.492       9.599      
wB97X-D     10.070   9.808   9.867   9.894     9.906 9.867 9.807   9.810  
B97D3   9.946     9.389   9.485   9.512   9.451 9.519   9.447   9.465 9.465
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 aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
Moller Plesset perturbation MP2 9.184 10.426 9.985   9.855         10.034   9.995 9.981 10.155      
MP2=FULL   10.426 9.982   9.841 9.841   9.956 9.956       9.977 10.147      
MP3         9.695                        
MP3=FULL         9.693   9.754                    
MP4   10.217                              
B2PLYP         9.667                 9.804      
B2PLYP=FULLultrafine         9.666               9.734 9.802   9.834  
Configuration interaction CID         9.610                        
CISD         9.578                        
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 aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
Quadratic configuration interaction QCISD   10.119 9.844 9.943 9.593 9.593   9.681 9.681       9.700 9.885      
Coupled Cluster CCD   10.405 9.961 10.253 9.761 9.761   9.848         9.869        
CCSD         9.643                        
CCSD(T)                           9.920      
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 aug-cc-pVDZ aug-cc-pVTZ 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 9.692 9.078   9.278 9.996 9.892     9.098
density functional B3LYP 10.010 9.586   9.707 10.221 10.128     9.689
PBEPBE                 9.479
Moller Plesset perturbation MP2   9.888     10.515 10.410     10.123
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.