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Computational Chemistry Comparison and Benchmark DataBase
Release 18October 2016
NIST Standard Reference Database 101
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XVII.C.1. (III.D.6.)

Calculated Ionization Energy for Be2 (Beryllium diatomic)

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 7.509
G3 7.516
G3B3 7.527
G4 7.543
CBS-Q 7.423

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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF 4.400 6.298 6.298 6.037 3.793 5.953 6.098 6.151 6.151 2.646 5.947 6.184 6.149 6.143 6.167 6.147 6.142
density functional LSDA 6.133 7.557 7.557 7.403 7.414 7.414 7.493 7.507 7.507 7.435   7.549 7.513   7.537    
SVWN   6.938     7.414   7.493       6.879            
BLYP 5.627 6.988 6.988 6.826 6.798 6.819 6.916 6.911 6.911 6.842   6.963 6.914        
B1B95 5.628 7.020 7.020 6.844 6.857 6.857 6.937 6.940 6.940 6.856   6.985 6.946   6.976    
B3LYP 5.687 7.097 7.097 6.927 6.918 6.918 7.009 7.015 7.015 6.938 6.889 7.065 7.017 7.015 7.056 7.017 7.015
B3LYPultrafine         6.918                     7.017  
B3PW91 5.603 7.039 7.039 6.880 6.880 6.880 6.946 6.956 6.956 6.891   6.998 6.958        
mPW1PW91 5.541 6.998 6.998 6.832 6.831 6.831 6.904 6.916 6.916 6.841   6.954 6.919        
M06-2X     5.875   6.787                        
PBEPBE 5.662 7.059 7.059 6.906 6.910 6.910 6.988 6.988 6.988 6.919   7.034 6.989        
PBE1PBE         6.834                        
HSEh1PBE   6.416     6.836               6.383        
TPSSh         6.305   6.367     6.315     6.409        
wB97X-D     6.203   6.042   6.114   6.150   6.108 6.114 6.165     6.167  
B97D3   6.238     6.083       6.164             6.197  
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
Moller Plesset perturbation MP2 5.257 7.019 7.019 6.807 6.719 6.759 6.868 6.913 6.953 3.945 5.868 6.953 6.985 7.007 6.949 6.992 7.014
MP2=FULL 5.264 7.028 7.028 6.816 6.755 6.755 6.864 6.957 6.957 6.815   6.953 6.912 7.000 6.948   7.004
MP3         7.104                        
MP3=FULL         5.928   7.160                    
MP4   7.624     7.232       7.397       7.392        
B2PLYP         6.828               6.978        
Configuration interaction CID   7.606 7.606 7.432 7.228     7.337                  
CISD   7.510 7.510 7.326 7.110     7.221                  
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
Quadratic configuration interaction QCISD   7.701 7.701 7.532 7.310 7.310 3.925 7.410 7.410 7.220   7.423 7.369        
QCISD(T)         7.237             7.384 7.382   7.381 7.384  
Coupled Cluster CCD   7.796 7.796 7.637 7.429 7.429 7.497 7.526 7.526 7.372   7.537 7.488   7.520 7.487  
CCSD         7.317                        
CCSD(T)         7.299             7.388 7.384 7.385 7.385 7.386 7.387
CCSD(T)=FULL         7.232                 7.373     7.373
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ

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 6.322 6.215 6.252 6.146 6.290 6.276
density functional B3LYP 7.036 6.997 6.978 6.941 7.079 7.048
Moller Plesset perturbation MP2 7.094 7.033 7.046 6.988 7.013 7.006
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.