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Calculated Ionization Energy for Al2 (Aluminum diatomic)

Experimental Ionization Energy is 5.4 ± 1 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 AM1  
PM3  
PM6  
composite G2 5.836
G3 5.955
G4 5.933
CBS-Q 5.848

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 Def2TZVPP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z
hartree fock HF -0.819 4.622 4.869 4.584 4.739 4.739 4.703 5.091 5.094 2.049   5.130 4.821 4.789 4.805 1.946 4.791  
ROHF         4.842                          
density functional LSDA 0.875 4.042 6.786 6.519 6.631 6.631 6.617 6.630 6.630         6.640 6.666 6.629    
BLYP   5.590 5.766 5.532 5.626 5.626 5.619 5.620 5.678 5.652       5.624 5.637      
B1B95 -0.011   5.935 5.652 5.771 5.796 5.778 5.774 5.774 5.839       5.812 5.791      
B3LYP 0.012 5.668 5.859 5.607 5.714 5.714 5.701 5.704 5.822 5.746   5.849 5.734 5.717 5.728 5.710 5.720  
B3LYPultrafine         5.714                       5.720  
B3PW91   5.913 6.110 5.827 5.956 5.956 5.935 5.941 5.999 5.994       5.967 5.978      
mPW1PW91 0.614 5.860 6.088 5.968 5.914 5.914 5.895 5.901 5.992 5.981       5.927 5.940      
M06-2X     5.846   5.674                          
PBEPBE   6.016 6.206 5.938 6.060 6.060 6.046 6.044 6.012 6.095     6.079 6.066 6.078      
PBE1PBE         6.017                          
HSEh1PBE   5.501     5.487   5.484               5.468      
TPSSh         5.993   5.974     6.025         6.005      
wB97X-D     6.433   6.305   6.293   6.303     6.299   6.293 6.287   6.282  
B97D3   5.681     5.831   5.820   5.744   5.783       5.762   5.766  
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 Def2TZVPP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z
Moller Plesset perturbation MP2   2.448 5.662 5.133 5.530 5.530 5.501 5.520 5.551 2.941   5.594 5.756 5.594 5.741 5.692 5.743  
MP2=FULL   5.178 5.687 5.138 5.555 5.555 5.522 5.530 5.550         5.619 5.805      
MP3         5.658                          
MP3=FULL         5.612   5.580                      
MP4         5.650                          
B2PLYP         5.285                   5.667      
Configuration interaction CID         2.482     2.484                    
CISD         2.553                          
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 Def2TZVPP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z
Quadratic configuration interaction QCISD   5.056     5.463 5.463 2.637 5.454           5.539 5.677      
QCISD(T)         5.600                          
Coupled Cluster CCD         5.439     5.430           5.511        
CCSD         5.448                          
CCSD(T)         5.590                 5.751 5.913 5.789 5.916 5.918
CCSD(T)=FULL         5.664                          
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 Def2TZVPP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z

Ionization Energies in eV
Methods with effective core potentials (select basis sets)
daug-cc-pVDZ daug-cc-pVTZ daug-cc-pVQZ Sadlej_pVTZ CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF         5.106 5.175 5.035 5.120 5.133 4.907
density functional B3LYP         5.826 5.876 5.750 5.806 5.866 5.688
Moller Plesset perturbation MP2         5.210 5.626 5.196 5.621 5.219 5.051
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.