National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 18October 2016
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 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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z
hartree fock HF 14.383 14.529 14.529 14.614 14.614 14.471 14.471 14.487 14.322 14.471 14.330 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
SVWN   15.457     15.556 15.478 15.478 15.472 15.377 15.478 15.382 15.283 15.360   15.269 15.358    
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 15.130 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 15.318 15.452 15.452 15.546 15.546 15.455 15.455 15.473 15.366 15.455 15.372 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 15.260 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 15.177 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 15.202 15.335 15.400 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 14.887 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 15.070 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 15.072 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       15.277             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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z
Moller Plesset perturbation MP2 14.742 15.066 15.066 15.145 15.145 15.291 15.291 14.983 15.137 15.291 15.138 15.027 15.235 15.669 15.248 15.260 15.667 15.673
MP2=FULL 14.742 14.958 14.958 15.045 15.045 15.303 15.303 14.914 15.195 15.303 15.192 15.040 15.998 14.821 14.973 15.242 12.707  
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 14.874 15.350 15.350 15.434 15.434 15.306 15.307 15.224 15.303 15.306 15.318 14.898 15.359     14.720    
B2PLYP=FULL   15.282 15.282 15.373 15.372 15.528 15.408 15.268 15.446 15.528 15.450 15.353 14.844     14.778    
B2PLYP=FULLultrafine   15.126 15.126 15.216 15.216 15.298 15.298 15.106 15.202 15.298 15.207 15.119 14.548     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) TZVP 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) TZVP 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)
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.