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

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II.A.1. (XV.A.)

Listing of experimental data for H2F2 (Hydrogen fluoride dimer)

Other names
Hydrogen fluoride dimer;
State Conformation
1Ag CS
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 -569.92 4.00 kJ mol-1 Gurvich
Hfg(0K) enthalpy of formation -566.50 4.00 kJ mol-1 Gurvich
Entropy (298.15K) entropy 260.90   J K-1 mol-1 Gurvich
Integrated Heat Capacity (0 to 298.15K) integrated heat capacity 13.87   kJ mol-1 Gurvich
Heat Capacity (298.15K) heat capacity 58.13   J K-1 mol-1 Gurvich
Information can also be found for this species in the NIST Chemistry Webbook
Vibrational levels (cm-1) vibrations
Mode Number Symmetry Frequency (cm-1) Frequency Reference Intensity (km mol-1) Int. unc. Intensity Reference Comment

Calculated vibrational frequencies for H2F2 (Hydrogen fluoride dimer).
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment

Calculated rotational constants for H2F2 (Hydrogen fluoride dimer).

Product of moments of inertia moments of inertia
amu3Å6   0gm3 cm6
Geometric Data
picture of Hydrogen fluoride dimer

Point Group Cs

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
rFF 2.780   2 4 1998Kuc r0 value
aHFF 117 3 2 4 1998Kuc
aHFF 10 1 4 2 1998Kuc


Atom x (Å) y (Å) z (Å)

Atom - Atom Distances bond lengths
Distances in Å


Calculated geometries for H2F2 (Hydrogen fluoride dimer).

Bond descriptions

Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond
Bond Type Count
H-F 2
H.F 1


Atom 1 Atom 2
H1 F2
H1 F4
F2 H3
Electronic energy levels (cm-1)
Energy (cm-1) Degeneracy reference description
0 1   1Ag
Dipole, Quadrupole and Polarizability
Electric dipole moment dipole
Calculated electric dipole moments for H2F2 (Hydrogen fluoride dimer).
Electric quadrupole moment quadrupole
Calculated electric quadrupole moments for H2F2 (Hydrogen fluoride dimer).

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squib reference DOI
1998Kuc K Kuchitsu(ed) "Structure of Free Polyatomic Molecules - Basic Data" Springer, Berlin, 1998  
Gurvich Gurvich, L.V.; Veyts, I. V.; Alcock, C. B., Thermodynamic Properties of Individual Substances, Fouth Edition, Hemisphere Pub. Co., New York, 1989 10.1351/pac198961061027

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