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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 Mg2 (Magnesium 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
composite G2 2.580
G3 6.506
G3B3 6.513
G4 6.515
CBS-Q 2.455
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z daug-cc-pVTZ
hartree fock HF -1.360 1.176 1.179 1.072 1.039 1.039 1.076 5.444 5.444 1.074   5.684 5.459 5.437 5.434 5.451 5.437 5.434   5.436
density functional LSDA 0.764 6.735 6.735 6.813 6.785 6.785 6.782 6.774 6.774 6.783     6.808 6.772   6.806 6.773   6.772  
BLYP 0.114 6.258 6.173 6.276 6.233 6.233 6.231 6.221 6.221 6.231     6.260 6.224            
B1B95 -0.089   6.064 6.207 6.158 6.177   6.173 6.173 6.172     6.192 6.150   6.173 6.150   6.150  
B3LYP 0.178 6.382 6.283 6.401 6.356 6.356 6.353 6.344 6.344 6.352   6.449 6.380 6.347 6.346 6.378 6.347 6.346    
B3LYPultrafine         6.356                       6.347      
B3PW91 0.071 6.219 6.160 6.258 6.224 6.224 6.222 6.206 6.206 6.218     6.239 6.209            
mPW1PW91 1.450 6.153 6.121 6.215 6.155 6.155 6.153 6.138 6.163 6.174     6.194 6.166         6.166  
M06-2X     6.133   6.232           6.223                  
PBEPBE 0.065 6.248 6.204 6.267 6.233 6.233 6.231 6.216 6.216 6.232     6.253 6.218         6.218  
PBE1PBE         6.192                              
HSEh1PBE   6.211     6.195                 6.181            
TPSSh         6.107   6.104     6.099       6.087            
wB97X-D     6.023   6.273   6.271   6.271     6.356 6.271 6.258     6.258      
B97D3   6.395     6.350   6.346   6.335   6.329 6.371   6.340     6.338     6.338
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z daug-cc-pVTZ
Moller Plesset perturbation MP2 -0.716 1.729 5.997 1.636 6.098 1.935 6.098 6.105 6.105 2.157   6.063 6.096 6.135 6.154 6.104 6.144 6.159 6.135  
MP2=FULL -0.732 1.733 6.000 6.109 6.102 6.102 1.979 6.134 6.134 6.117     6.095 6.136 6.215     6.216    
MP3         6.303                              
MP3=FULL         6.302   6.304                          
MP4   6.475     2.345       6.353         6.340            
B2PLYP         6.234                 6.239            
B2PLYP=FULLultrafine         6.234               6.249 6.240     6.242      
Configuration interaction CID   6.432 6.170 6.463 6.283     6.282                        
CISD   6.361 6.085 6.388 6.195     6.194                        
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z daug-cc-pVTZ
Quadratic configuration interaction QCISD   1.904 6.190 6.502 2.062 6.302 6.300 6.300 6.300 6.284     6.304 6.277         6.277  
QCISD(T)         6.295               6.297 6.280   6.295 6.284      
Coupled Cluster CCD   6.542 6.275 6.576 2.101 6.391 6.388 6.390 6.390 6.376     6.393 6.371   6.387 6.373      
CCSD         2.054                              
CCSD(T)                         6.299 6.283   6.298 6.287   6.283  
CCSD(T)=FULL         6.289                              
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z 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 5.637 5.537 5.559 5.461 5.601 5.990     5.454
density functional B3LYP 6.332 6.278 6.253 6.207 6.304 6.701     6.358
PBEPBE                 6.232
Moller Plesset perturbation MP2 6.198 6.176 6.135 6.121 6.197 6.565     6.114
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.