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 Cl (Chlorine atom)

Experimental Ionization Energy is 12.96764 eV
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 G1 12.867
G2MP2 12.789
G2 12.846
G3 12.890
G3B3 12.903
G3MP2 12.874
G4 12.920
CBS-Q 12.923
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) 6-311+G(3df,2pd) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ daug-cc-pVTZ
hartree fock HF 11.224 11.851 11.841 11.796 11.781 11.781 11.782 11.821 11.821 11.777 11.774 11.774 11.782 11.815 11.774 11.766 11.829 11.775 11.766 11.774
ROHF 11.224 11.860 11.864 11.804 11.804 11.804 11.804 11.844 11.844 11.796 11.795 11.795 11.802 11.833 11.795 11.786 11.845 11.794 11.786  
density functional LSDA 13.158 10.514 13.666 13.662 13.612 13.626 13.658 13.708 12.869 13.710 13.725 13.725 13.724 13.135 12.659 13.722 13.116 13.728 13.724  
BLYP 12.347 12.860 12.854 12.849 12.843 12.843 12.905 12.958 12.958 12.845 12.909 12.909 12.893 12.835 12.893 12.901 12.930 12.912 12.907  
B1B95 12.607   12.938 12.907 12.903 12.903 12.929 12.974 12.974 12.901 12.928 163.990 12.926 12.916 12.922 12.919 12.960 12.929 12.921  
B3LYP 12.575 13.059 13.054 13.036 13.030 13.030 13.071 13.120 13.120 13.031 13.072 13.072 13.065 13.033 13.064 13.066 13.100 13.074 13.069  
B3LYPultrafine 12.575 13.059 13.054 13.036 13.030 13.030 13.071 13.120 13.120 13.031 13.072 13.072 13.065 13.033 13.064 13.066 13.100 13.074 13.069  
B3PW91 12.661 13.070 13.059 13.022 13.016 13.016 13.036 13.077 13.077 13.014 13.031 13.031 13.036 13.037 13.032 13.029 13.072 13.035 13.032  
mPW1PW91 12.623 13.023 13.012 12.978 12.971 12.971 12.993 13.032 13.032 12.969 12.988 12.988 12.990 12.991 12.986 12.989 13.027 12.993 12.993  
M06-2X 12.530 12.995 13.003 12.998 12.990 12.990 13.015 13.038 13.038 12.988 12.997 12.997 13.005 12.979 13.004 12.992 13.029 13.008 12.993  
PBEPBE 12.511 12.964 12.953 12.941 12.934 12.934 12.977 13.023 13.023 12.933 12.976 12.976 12.966 12.936 12.963 12.967 13.002 12.979 12.973  
PBEPBEultrafine 12.511 12.964 12.953 12.941 12.934 12.934 12.977 13.023 13.023 12.933 12.976 12.976 12.966 12.936 12.963 12.967 13.002 12.979 12.973  
PBE1PBE 12.557   12.977 12.949 12.941 12.941 12.964 13.006 13.006 12.940 12.960 12.960 12.960 12.957 12.956 12.953 12.995 12.963 12.957  
HSEh1PBE 12.548 12.985 12.976 12.944 12.937 12.937 12.960 13.005 13.005 12.936 12.958 12.958 12.958 12.953 12.954 12.952 12.992 12.960 12.954  
TPSSh 12.512 12.962 12.947 12.935 12.927 12.927 12.949 12.998 12.998 12.926     12.953 12.936 12.950 12.943 12.970 12.956 12.947  
wB97X-D 12.632 13.115 13.104 13.021 13.014 13.014 13.031 13.074 13.074 13.014     13.036 13.057 13.030 13.039 13.091 13.033 13.042  
B97D3 12.540 12.878 12.861 12.839 12.827 12.827 12.866 12.907 12.907 12.832 12.867   12.872 12.838 12.867 12.879 12.895 12.878 12.884  
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) 6-311+G(3df,2pd) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ daug-cc-pVTZ
Moller Plesset perturbation MP2 11.224 12.185 12.353 12.131 12.298 12.298 12.305 12.369 12.369 12.681 12.713 12.713 12.379 12.423 12.709 12.841 12.605 12.766 12.865  
MP2=FULL 11.223 12.188 12.355 12.132 12.299 12.299 12.306 12.366 12.366 12.690 12.716 12.716 12.379 12.427 12.712 12.847 12.609 12.769 12.872  
ROMP2     12.346 12.134 12.291 12.291 12.298 12.362 12.362 12.671     12.373 12.417 12.699   12.599      
MP3   12.218 12.316 12.170 12.268 12.268 12.275 12.328 12.328 12.695 12.718 12.718 12.344 12.394 12.714 12.862 12.593 12.774 12.884  
MP3=FULL   12.217 12.313 12.169 12.265 12.265 12.271 12.319 12.319 12.694     12.337 12.394 12.708   12.592 12.768    
MP4   12.225 12.300 12.183 12.254 12.254 12.263 12.318 12.318 12.689 12.725 12.725 12.326 12.369 12.717 12.879 12.578 12.785 12.902  
MP4=FULL   12.225 12.299 12.183 12.253 12.253 12.261 12.311 12.311 12.693 12.722 12.722 12.322 12.370 12.715 12.880 12.579 12.783 12.904  
B2PLYP 12.080 12.716 12.761 12.683 12.726 12.726 12.753 12.805 12.805 12.852     12.772 12.769 12.878   12.875 12.905    
B2PLYP=FULL 12.080 12.717 12.761 12.684 12.726 12.726 12.754 12.805 12.805 12.854     12.772 12.770 12.879   12.876 12.906    
B2PLYP=FULLultrafine 12.080 12.717 12.761 12.684 12.726 12.726 12.754 12.805 12.805 12.854     12.772 12.770 12.879   12.876 12.906    
Configuration interaction CID   12.216 12.258 12.170 12.209 12.209 12.216 12.266 12.266 12.580 12.596 12.596 12.276 12.325 12.599 12.729 12.498 12.648 12.748  
CISD   12.216 12.256 12.173 12.204 12.204 12.212 12.265 12.265 12.574 12.590 12.590 12.273 12.320 12.593 12.723 12.494 12.642 12.741  
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) 6-311+G(3df,2pd) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ daug-cc-pVTZ
Quadratic configuration interaction QCISD   12.226 12.290 12.183 12.239 12.239 12.249 12.302 12.302 12.649 12.672 12.672 12.314 12.360 12.672 12.815 12.552 12.727 12.835  
QCISD(T)   12.227 12.295 12.186 12.249 12.249 12.260 12.314 12.314 12.679 12.715 12.715 12.322 12.362 12.708 12.867 12.573 12.776 12.891  
QCISD(T)=FULL         12.248   12.259             12.363 12.707 12.869 12.573 12.775 12.893  
QCISD(TQ)   12.227 12.294 12.185 12.249 12.249 12.260 12.313 12.313 12.679 12.715 12.715 12.322 12.363 12.708 12.867 12.574 12.776 12.891  
QCISD(TQ)=FULL         12.248   12.258             12.363 12.706 12.868 12.575 12.774 12.891  
Coupled Cluster CCD   12.226 12.292 12.180 12.244 12.244 12.251 12.302 12.302 12.655 12.676 12.676 12.316 12.364 12.677 12.820 12.554 12.732 12.840  
CCSD   12.226 12.289 12.182 12.239 12.239 12.248 12.301 12.301 12.650 12.672 12.672 12.313 12.360 12.673 12.815 12.551 12.728 12.836  
CCSD=FULL   12.225 12.288 12.180 12.237 12.237 12.246 12.295 12.295 12.653 12.669 12.669 12.308 12.360 12.670 12.815 12.551 12.725 12.835  
CCSD(T)   12.226 12.295 12.185 12.249 12.249 12.260 12.314 12.314 12.679 12.715 12.715 12.321 12.362 12.709 12.868 12.572 12.777 12.892  
CCSD(T)=FULL   12.226 12.294 12.184 12.248 12.248 12.259 12.308 12.308 12.684 12.714 12.714 12.317 12.363 12.707 12.869 12.573 12.775 12.893  
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) 6-311+G(3df,2pd) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ 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 11.881 11.861 11.786 11.771 12.059 11.806     11.773
ROHF 11.889 11.882 11.795 11.794 12.067 11.816      
density functional LSDA 13.611 13.604 13.517 13.516 13.730 13.690      
BLYP 12.879 12.866 12.777 12.773 12.958 12.820      
B1B95 12.895 12.881 12.798 12.792 13.038 12.909      
B3LYP 13.072 13.060 12.969 12.964 13.182 13.022     13.059
B3LYPultrafine 13.072 13.060 12.969 12.964 13.182 13.022      
B3PW91 13.060 13.048 12.955 12.949 13.217 13.040      
mPW1PW91 13.024 13.012 12.918 12.911 13.176 12.990      
M06-2X 12.922 12.909 12.840 12.833 12.992 12.979      
PBEPBE 12.980 12.968 12.877 12.872 13.083 12.919     12.961
PBEPBEultrafine 12.980 12.968 12.877 12.872 13.083 12.919      
PBE1PBE 12.997 12.985 12.893 12.886 13.136 12.946      
HSEh1PBE 12.995 12.982 12.891 12.884 13.135 12.945      
wB97X-D 13.036 13.027 12.942 12.938 13.244 13.088      
Moller Plesset perturbation MP2 12.128 12.419 12.099 12.374 12.281 12.117     12.716
MP2=FULL 12.128 12.419 12.099 12.374 12.281 12.107      
MP3 12.162 12.383 12.139 12.345 12.307 12.141      
MP4 12.173 12.360 12.155 12.325 12.311 12.149      
MP4=FULL 12.173 12.360 12.155 12.325 12.311 12.136      
Configuration interaction CID 12.165 12.318 12.141 12.274 12.308 12.139      
CISD 12.168 12.312 12.146 12.269 12.308 12.140      
Quadratic configuration interaction QCISD 12.173 12.348 12.156 12.312 12.311 12.149      
QCISD(T) 12.176 12.354 12.160 12.321 12.311 12.152      
QCISD(TQ) 12.175 12.355 12.159 12.321 12.311 12.152      
Coupled Cluster CCD 12.169 12.353 12.150 12.317 12.311 12.148      
CCSD 12.172 12.348 12.154 12.312 12.311 12.149      
CCSD=FULL 12.172 12.348 12.154 12.312 12.311 12.135      
CCSD(T) 12.175 12.354 12.159 12.321 12.311 12.151      
CCSD(T)=FULL 12.175 12.354 12.159 12.321 12.311 12.138      
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.