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Experimental data for H2 (Hydrogen diatomic)

22 02 02 11 45
Other names
Hydrogen; Molecular hydrogen; o-Hydrogen; p-Hydrogen; dihydrogen;
INChI INChIKey SMILES IUPAC name
InChI=1S/H2/h1H UFHFLCQGNIYNRP-UHFFFAOYSA-N [H][H] dihydrogen
State Conformation
1Σg D*H
Enthalpy of formation (Hfg), Entropy, Integrated heat capacity (0 K to 298.15 K) (HH), Heat Capacity (Cp)
Property Value Uncertainty units Reference Comment
Hfg(298.15K) enthalpy of formation 0.00 0.00 kJ mol-1 CODATA
Hfg(0K) enthalpy of formation 0.00 0.00 kJ mol-1 CODATA
Entropy (298.15K) entropy 130.68 0.00 J K-1 mol-1 CODATA
Integrated Heat Capacity (0 to 298.15K) integrated heat capacity 8.47 0.00 kJ mol-1 CODATA
Heat Capacity (298.15K) heat capacity 28.84   J K-1 mol-1 CODATA
Information can also be found for this species in the NIST Chemistry Webbook
Vibrational levels (cm-1) vibrations
Mode Number Symmetry Frequency Intensity Comment Description
Fundamental(cm-1) Harmonic(cm-1) Reference (km mol-1) unc. Reference
1 Σg 4161 4401 1979HUB/HER      

Detailed diatomic data
ωe ωexe ωeye Be αe ZPE reference
4401.213 121.336 0.8129 60.853 3.0622 2179.307 2007Iri:389

vibrational zero-point energy: 2080.6 cm-1 (from fundamental vibrations)
Calculated vibrational frequencies for H2 (Hydrogen diatomic).
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment
  60.85300   1979HUB/HER

Calculated rotational constants for H2 (Hydrogen diatomic).
Product of moments of inertia moments of inertia
0.2770222amu Å2   4.600183E-41gm cm2
Geometric Data
picture of Hydrogen diatomic

Point Group D∞h


Internal coordinates
distances (r) in Å, angles (a) in degrees, dihedrals (d) in degrees
Description Value unc. Connectivity Reference Comment
Atom 1 Atom 2 Atom 3 Atom 4
rHH 0.741   1 2 1979HUB/HER re

Cartesians
Atom x (Å) y (Å) z (Å)
H1 0.0000 0.0000 0.0000
H2 0.0000 0.0000 0.7414

Atom - Atom Distances bond lengths
Distances in Å
  H1 H2
H1   0.7414
H2 0.7414  

Calculated geometries for H2 (Hydrogen diatomic).

Bond descriptions


Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond
Bond Type Count
H-H 1

Connectivity
Atom 1 Atom 2
H1 H2
Electronic energy levels (cm-1)
Energy (cm-1) Degeneracy reference description
0 1 1979HUB/HER 1Σg
91700 1 1979HUB/HER

Ionization Energies (eV)
Ionization Energy I.E. unc. vertical I.E. v.I.E. unc. reference
15.426 0.000     webbook
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