National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 17bSeptember 2015
NIST Standard Reference Database 101
IIntroduction
IIExperimental data
IIICalculated data
IVData comparisons
VCost comparisons
VIInput and output files
VIITutorials and Units
VIIILinks to other sites
IXFeedback
XOlder CCCBDB versions
XIIGeometries
XIII Vibrations
XIVReaction data
XVEntropy data
XVIBibliographic data
XVIIIon data
XVIIIBad calculations
XIXIndex of properties
XXH-bond dimers
XXIOddities

NIST policy on privacy, security, and accessibility.

Please rate our products
© 2013 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.

Please send questions, comments, corrections, additions and suggestions to cccbdb@nist.gov.

return to home page

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
composite G2 15.321
G3 15.273
G3B3 15.262
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   14.222 14.303   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   15.283 15.360   15.269     15.360
SVWN                     15.382              
BLYP 15.059 15.192 15.192 15.290 15.290 15.213 15.213 15.240 15.148 15.213   14.990 15.138         15.138
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   15.228 15.353   15.354
B3LYPultrafine         15.546                     15.353    
B3PW91 15.260 15.389 15.389 15.475 15.475 15.373 15.373 15.388 15.271 15.373   15.170 15.256         15.256
mPW1PW91 15.177 15.299 15.305 15.389 15.383 15.278 15.278 15.302 15.185 15.283   15.080 15.164         15.164
M06-2X     15.400   15.400                          
PBEPBE 14.942 15.081 15.081 15.169 15.169 15.081 15.081 15.110 15.006 15.081   14.887 14.994         14.994
PBE1PBE         15.292                          
HSEh1PBE   15.208     15.292   15.322           15.204          
TPSSh         15.586   15.477     15.477     15.356          
wB97X-D     15.356   15.446       15.231       15.215     15.216    
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 14.958 14.958 15.045 15.145 15.230 15.230 14.983 15.137 15.230   15.040 15.673 15.213 15.248   15.217 15.673
MP2=FULL 14.742 14.958 14.958 15.045 15.045 15.230 15.230 14.980 15.085 15.229   15.040 15.998 15.213 14.973      
MP4   15.199     15.285       15.290       15.511          
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                
QCISD(T)         15.308                          
Coupled Cluster CCD   15.220 15.220 15.305 15.305 15.393 15.393 15.195 15.303 15.393                
CCSD         15.308                          
CCSD(T)         15.308                          
CCSD(T)=FULL         15.345                          
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 14.978 14.978 14.980 14.980 14.978 14.978
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.