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Calculated Ionization Energy for H2 (Hydrogen diatomic)

Experimental Ionization Energy is 15.42593 ± 0.00005 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  
composite G2 15.321
G3 15.273
G3B3 15.262
G3MP2 15.307
G4 15.302
CBS-Q 15.322

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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z
hartree fock HF   14.529 14.529 14.614 14.614 14.471 14.471 14.487 14.322 14.471   14.330 14.303 14.249 14.303 14.309 14.222 14.303 14.308 14.303
density functional LSDA 15.278 15.457 15.457 15.556 15.556 15.478 15.478 15.472 15.376 15.478   15.382   15.283 15.360   15.269 15.358   15.360
BLYP 15.059 15.192 15.192 15.290 15.290 15.213 15.213 15.240 15.148 15.213   15.153   14.990 15.138   14.997 15.138   15.138
B1B95   15.257 15.257 15.349 15.349 15.429 15.248 15.349 15.155 15.248   15.161   15.032 15.142   15.025 15.142    
B3LYP   15.452 15.452 15.546 15.546 15.455 15.455 15.473 15.366 15.455   15.372 15.354 15.233 15.354 15.361 15.228 15.353 15.361 15.354
B3LYPultrafine   15.452     15.546 15.455 15.455 15.473       15.371   15.233 15.354   15.228 15.353    
B3PW91   15.389 15.389 15.474 15.474 15.373 15.373 15.388 15.271 15.373   15.276   15.170 15.256   15.159 15.255   15.256
mPW1PW91   15.299 15.305 15.389 15.383 15.277 15.277 15.302 15.185 15.283   15.191   15.080 15.164   15.078 15.169   15.164
M06-2X   15.335 15.335 15.400 15.400 15.328 15.328 15.338 15.243 15.328   15.248   15.137 15.228   15.127 15.227    
PBEPBE 14.942 15.081 15.081 15.169 15.169 15.080 15.080 15.110 15.006 15.080   15.011 14.994 14.887 14.994   14.887 14.993   14.994
PBEPBEultrafine   15.081     15.169 15.080 15.080 15.110       15.011   14.887 14.994   14.887 14.993    
PBE1PBE   15.209 15.209 15.292 15.292 15.377 15.187 15.211 15.089 15.187   15.095   14.992 15.074   14.981 15.073    
HSEh1PBE   15.208 15.208 15.292 15.292 15.190 15.190 15.212 15.091 15.190   15.097   14.992 15.204   14.981 15.076    
TPSSh   15.508 15.508 15.586 15.586 15.477 15.477 15.495   15.477   15.378   15.291 15.356   15.281 15.355    
wB97X-D     15.356   15.446   15.342   15.231     15.238   15.219 15.215     15.216    
B97D3   15.377     15.477   15.382   15.277   15.269       15.263     15.261    
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z
Moller Plesset perturbation MP2   15.066 15.066 15.145 15.145 15.291 15.291 14.983 15.137 15.291   15.138 15.245 15.027 15.235 15.213   15.260 15.217  
MP2=FULL   14.958 14.958 15.045 15.045 15.303 15.303 14.914 15.195 15.303   15.192   15.040   15.213 14.973 15.242    
MP3         15.238   15.341         15.251   15.147 15.324          
MP3=FULL         15.238   15.341         15.251   15.147 15.324          
MP4   15.199     15.285       15.290     15.293   15.192 15.366   15.197 15.372    
MP4=FULL   15.199     15.285       15.290         15.192 15.366   15.197 15.372    
B2PLYP   15.350 15.350 15.434 15.434 15.306 15.307 15.224 15.303 15.306   15.318     15.359          
B2PLYP=FULL   15.282 15.282 15.373 15.372   15.408 15.268                        
B2PLYP=FULLultrafine   15.126 15.126 15.216 15.216     15.106                   15.111    
Configuration interaction CID   15.220 15.220 15.305 15.305     15.195                        
CISD     15.223 15.308 15.308     15.199                        
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z
Quadratic configuration interaction QCISD   15.224 15.223 15.308 15.308 15.399 15.399 15.199 15.309 15.399   15.311   15.212 15.384   15.216 15.391    
QCISD(T)         15.308     15.199       15.311   15.212 15.384   15.216 15.391    
QCISD(T)=FULL         15.308   15.399             15.212 15.384 15.416 15.216 15.391 15.418  
Coupled Cluster CCD   15.220 15.220 15.305 15.305 15.393 15.393 15.195 15.303 15.393   15.306   15.207 15.380   15.212 15.387    
CCSD         15.308         15.400   15.311   15.212 15.384 15.416 15.216 15.391 15.418  
CCSD=FULL         15.308         15.400   15.311   15.212 15.384 15.416 15.216 15.391 15.418  
CCSD(T)         15.308 15.399 15.399 15.199   15.399   15.311   15.212 15.384 15.416 15.216 15.391 15.418  
CCSD(T)=FULL         15.308             15.311   15.212 15.384 15.416 15.216 15.391 15.418  
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ 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         14.546 14.546 14.487 14.487 14.546 14.546
density functional B3LYP         15.470 15.470 15.473 15.473 15.470 15.470
Moller Plesset perturbation MP2         15.070 15.070 14.982 14.982 15.070 15.070
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.