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)	26.50	0.10	kJ mol-1	CODATA
Hfg(0K)	28.68	0.10	kJ mol-1	CODATA
Entropy (298.15K)	206.59		J K-1 mol-1	webbook
Integrated Heat Capacity (0 to 298.15K)	8.66		kJ mol-1	Gurvich
Heat Capacity (298.15K)	29.16		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
1	Σ	2309	webbook

vibrational zero-point energy: 1154.5 cm^-1
Calculated vibrational frequencies for HI (Hydrogen iodide).

Rotational Constants (cm^-1)
See section I.F.4 to change rotational constant units

A	B	C	reference	comment
	6.42637	6.42637	webbook

Calculated rotational constants for HI (Hydrogen iodide).

Product of moments of inertia
2.623199	amu Å2		4.355992E-40	gm cm2

Geometric Data

Point Group C_∞v

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
rHI	1.609	0.000	1	2			NISTdiatomic	re

Cartesians

Atom	x (Å)	y (Å)	z (Å)
I1	0.0000	0.0000	0.0000
H2	0.0000	0.0000	1.6092

Atom - Atom Distances
Distances in Å

	I1	H2
I1		1.6092
H2	1.6092

Calculated geometries for HI (Hydrogen iodide).

Bond descriptions
Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond

Bond Type	Count
H-I	1

Connectivity

Atom 1	Atom 2
I1	H2

Electronic energy levels (cm^-1)

Energy (cm-1)	Degeneracy	reference	description
0	1

Ionization Energies (eV)

Ionization Energy	I.E. unc.	vertical I.E.	v.I.E. unc.	Electron Affinity	E.A. unc.	reference
10.386	0.001					webbook

Dipole, Quadrupole and Polarizability
Electric dipole moment

Dipole (Debye)	Reference	comment
0.448	webbook

Calculated electric dipole moments for HI (Hydrogen iodide).
Electric quadrupole moment
Calculated electric quadrupole moments for HI (Hydrogen iodide).

References
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squib	reference	DOI
CODATA	Cox, J.D.; Wagman, D.D.; Medvedev, V.A.CODATA Key Values for Thermodynamics. Hemisphere, New York, 1989
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
NISTdiatomic	NIST Diatomic Spectral Database (www.physics.nist.gov/PhysRefData/MolSpec/Diatomic/index.html)
webbook	NIST Chemistry Webbook (http://webbook.nist.gov/chemistry)

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