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)	-569.92	4.00	kJ mol-1	Gurvich
Hfg(0K)	-566.50	4.00	kJ mol-1	Gurvich
Entropy (298.15K)	260.90		J K-1 mol-1	Gurvich
Integrated Heat Capacity (0 to 298.15K)	13.87		kJ mol-1	Gurvich
Heat Capacity (298.15K)	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)

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)
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
	amu3Å6		0	gm3 cm6

Geometric Data

Point Group C_s

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

Cartesians

Atom	x (Å)	y (Å)	z (Å)

Atom - Atom Distances
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

Connectivity

Atom 1	Atom 2
H1	H3
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
Calculated electric dipole moments for H₂F₂ (Hydrogen fluoride dimer).
Electric quadrupole moment
Calculated electric quadrupole moments for H₂F₂ (Hydrogen fluoride dimer).

References
By selecting the following links, you may be leaving NIST webspace. We have provided these links to other web sites because they may have information that would be of interest to you. No inferences should be drawn on account of other sites being referenced, or not, from this page. There may be other web sites that are more appropriate for your purpose. NIST does not necessarily endorse the views expressed, or concur with the facts presented on these sites. Further, NIST does not endorse any commercial products that may be mentioned on these sites. Please address comments about this page to cccbdb@nist.gov.

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

Got a better number? Please email us at cccbdb@nist.gov