National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 22May 2022
NIST Standard Reference Database 101
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XIXIndex of properties
XXH-bond dimers
XXIOddities

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

Calculated Ionization Energy for Be (Beryllium atom)

Experimental Ionization Energy is 9.32263 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 PM3  
PM6  
composite G1 9.441
G2MP2 9.445
G2 9.413
G3 9.458
G3B3 9.471
G3MP2 9.552
G4 9.357
CBS-Q 9.367

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 6.913 8.078 8.078 7.928 8.066 7.930 8.006 8.046 8.046 7.934 8.047 8.047 7.862 8.079 8.045 8.043 8.075 8.044 8.043 8.044
density functional LSDA 8.387 9.499 9.499 9.382 9.392 9.392 9.446 9.456 9.456 9.396 9.458 9.458 9.287 9.492 9.456 9.458 9.488 9.456 9.458  
BLYP 7.997 9.047 9.047 8.919 8.920 8.920 8.986 8.978 8.978 8.925 8.982 8.982 8.824 9.028 8.977 8.976 9.026 8.977 8.976  
B1B95 7.937 8.924 8.924 8.822 8.837 8.837 8.892 8.892 8.892 8.824 8.887 8.893 8.739 8.932 8.898 8.882 8.936 8.892 8.883  
B3LYP 8.130 9.179 9.179 9.049 9.049 9.049 9.110 9.113 9.113 9.054 9.116 9.116 8.942 9.161 9.110 9.109 9.158 9.110 9.110  
B3LYPultrafine 8.130 9.179 9.179 9.049 9.049 9.049 9.110 9.113 9.113 9.054 9.116 9.116 8.942 9.161 9.110 9.109 9.158 9.110 9.110  
B3PW91 8.006 9.053 9.053 8.944 8.951 8.951 8.996 9.002 9.002 8.949 9.002 9.002 8.812 9.042 8.997 9.001 9.038 8.997 9.001  
mPW1PW91 7.978 9.021 9.032 8.917 8.912 8.912 8.963 8.972 8.983 8.919 8.984 8.984 8.793 9.020 8.977 8.979 9.016 8.977 8.980  
M06-2X 8.144 9.118 9.118 8.999 9.372 8.999 9.064 9.062 9.062 8.988 9.065 9.065 8.910 9.108 9.064 9.057 9.107 9.063 9.057  
PBEPBE 7.991 9.044 9.044 8.940 8.948 8.948 9.003 9.002 9.002 8.942 9.004 9.004 8.842 9.043 8.995 8.997 9.040 8.995 8.997  
PBEPBEultrafine 7.991 9.044 9.044 8.940 8.948 8.948 9.003 9.002 9.002 8.942 9.004 9.004 8.842 9.043 8.995 8.997 9.040 8.995 8.997  
PBE1PBE 7.961 9.018 9.018 8.909 8.916 8.916 8.967 8.977 8.977 8.912 8.978 8.978 8.796 9.015 8.970 8.972 9.012 8.970 8.973  
HSEh1PBE 7.957 8.765 9.016 8.905 8.912 8.912 8.962 8.973 8.973 8.908 8.974 8.974 8.791 9.011 8.718 8.968 9.007 8.966 8.968  
TPSSh         9.004   9.047     9.001         9.056          
wB97X-D     8.887   8.766   8.818   8.830       8.643 8.818 8.837     8.837    
B97D3   9.301     9.124   9.182   9.216   9.218   9.007   9.229     9.228    
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 7.560 8.689 8.689 8.561 8.646 8.646 8.709 8.772 8.772 8.702 8.807 8.807 8.491 8.776 8.811 8.844 8.776 8.815 8.846  
MP2=FULL 7.567 8.697 8.697 8.569 8.650 8.650 8.713 8.785 8.785 8.708 8.822 8.822 8.493 8.782 8.823 8.866 8.782 8.827 8.869  
MP3 7.943 8.995 8.995 8.886 8.933 8.932 8.984 9.044 9.044 8.961 9.051 9.051 8.799 9.052 9.053 9.063 9.049 9.054 9.063  
MP3=FULL         8.931   8.983                          
MP4 8.154 9.151 9.150 9.051 9.072 9.071 9.117 9.167 9.167 9.084 9.167 9.167 8.954 9.177 9.168 9.177 9.173 9.169 9.177  
MP4=FULL   9.152 9.152 9.053 9.068 9.068 9.114 9.169 9.169 9.084 9.171 9.171 8.951 9.178 9.171 9.187 9.174 9.171 9.187  
B2PLYP         8.906                              
Configuration interaction CID 8.313 9.266 9.266 9.173 9.188 9.188 9.226 9.270 9.268 9.197 9.270 9.270 9.062 9.278 9.271 9.279 9.274 9.271 9.279  
CISD 8.313 9.273 9.273 9.180 9.196 9.196 9.240 9.282 9.280 9.205 9.284 9.284 9.079 9.290 9.284 9.294 9.286 9.285 9.295  
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 8.313 9.273 9.273 9.180 9.196 9.196 9.240 9.282 9.280 9.205 9.284 9.284 9.079 9.290 9.284 9.294 9.286 9.285 9.295  
QCISD(T) 8.313 9.272 9.272 9.180 9.196 9.196 9.239 9.281 9.280 9.205 9.284 9.284 9.079 9.290 9.284 9.294 9.286 9.285 9.295  
Coupled Cluster CCD 8.313 9.266 9.266 9.173 9.188 9.188 9.226 9.270 9.268 9.197 9.270 9.270 9.062 9.278 9.271 9.279 9.274 9.271 9.279  
CCSD   9.272 9.272 9.180 9.196 9.196 9.239 9.281 9.280 9.205 9.284 9.284 9.079 9.290 9.284 9.294 9.286 9.285 9.295  
CCSD=FULL   9.270 9.270 9.177 9.188 9.188 9.231 9.271 9.271 9.201 9.277 9.277 9.070 9.289 9.278 9.289 9.285 9.279 9.290  
CCSD(T)   9.272 9.272 9.180 9.196 9.196 9.239 9.281 9.280 9.205 9.284 9.284 9.079 9.289 9.284 9.295 9.286 9.284 9.295  
CCSD(T)=FULL   9.271 9.271 9.178 9.191 9.191 9.146 9.278 9.278 9.205 9.286 9.286 9.074 9.289 9.284 9.302 9.286 9.285 9.303  
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 8.211 8.206 8.065 8.060 8.065 8.034     8.042
density functional LSDA 9.464 9.466 9.335 9.337 9.480 9.442      
BLYP 8.968 8.962 8.837 8.830 9.020 8.967      
B1B95 8.942 8.937 8.806 8.801 8.901 8.859      
B3LYP 9.133 9.128 8.997 8.991 9.150 9.100     9.108
B3LYPultrafine 9.133 9.128 8.997 8.991 9.150 9.100      
B3PW91 9.139 9.140 8.997 8.998 9.024 8.976      
mPW1PW91 9.068 9.069 8.926 8.927 9.002 8.955      
M06-2X 9.167 9.186 9.084 9.101 9.080 9.043      
PBEPBE 8.998 8.998 8.862 8.861 9.029 8.980     8.995
PBEPBEultrafine 8.998 8.998 8.862 8.861 9.029 8.980      
PBE1PBE 9.019 9.020 8.879 8.879 8.999 8.953      
HSEh1PBE 9.012 9.011 8.871 8.870 8.995 8.949      
Moller Plesset perturbation MP2 8.833 8.931 8.718 8.815 8.676 6.519     8.751
MP2=FULL 8.833 8.931 8.718 8.815 8.680 8.653      
ROMP2 8.211   8.065   8.065 8.036      
MP3 9.163 9.220 9.048 9.102 8.990 8.967      
MP4 9.332 9.354 9.213 9.233 9.149 9.126      
MP4=FULL 9.332 9.354 9.213 9.233 9.149 9.123      
Configuration interaction CID 9.443 9.456 9.317 9.330 9.257 9.233      
CISD 9.454 9.467 9.334 9.348 9.269 9.244      
Quadratic configuration interaction QCISD 9.454 9.467 9.334 9.348 9.269 9.244      
QCISD(T) 9.454 9.467 9.334 9.348 9.269 9.244      
Coupled Cluster CCD 9.443 9.456 9.317 9.330 9.257 9.233      
CCSD 9.454 9.467 9.334 9.348 9.269 9.244      
CCSD=FULL 9.454 9.467 9.334 9.348 9.267 9.237      
CCSD(T) 9.454 9.467 9.334 9.348 9.269 9.244      
CCSD(T)=FULL 9.454 9.467 9.334 9.348 9.267 9.240      
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.