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)	142.07	1.20	kJ mol-1	JANAF
Hfg(0K)	144.59	1.20	kJ mol-1	JANAF
Entropy (298.15K)	230.24	0.03	J K-1 mol-1	JANAF
Integrated Heat Capacity (0 to 298.15K)	10.40		kJ mol-1	JANAF
Heat Capacity (298.15K)	37.59		J K-1 mol-1	webbook

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	Σg	159	1979HUB/HER

Detailed diatomic data

ωe	ωexe	ωeye	Be	αe	ZPE	reference
159.0855	0.7086557	-4.632416E-03	0.1547354	8.63753E-04	79.33591	2007Iri:389

vibrational zero-point energy: 79.6 cm^-1
Calculated vibrational frequencies for Na₂^- (sodium dimer anion).

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

A	B	C	reference	comment
	0.15471		1979HUB/HER

Calculated rotational constants for Na₂^- (sodium dimer anion).

Product of moments of inertia
108.9649	amu Å2		1.809433E-38	gm cm2

Geometric Data

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
rNaNa	3.079		1	2			1979HUB/HER

Cartesians

Atom	x (Å)	y (Å)	z (Å)
Na1	0.0000	0.0000	0.0000
Na2	0.0000	0.0000	3.0789

Atom - Atom Distances
Distances in Å

	Na1	Na2
Na1		3.0789
Na2	3.0789

Calculated geometries for Na₂^- (sodium dimer anion).

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

Bond Type	Count
Na-Na	1

Connectivity

Atom 1	Atom 2
Na1	Na2

Electronic energy levels (cm^-1)

Energy (cm-1)	Degeneracy	reference	description
0	1	1979HUB/HER	1Σg

Ionization Energies (eV)

Ionization Energy	I.E. unc.	vertical I.E.	v.I.E. unc.	Electron Affinity	E.A. unc.	reference
4.892	0.003			0.430	0.015	webbook

Dipole, Quadrupole and Polarizability
Electric dipole moment
For a molecule with D_∞h symmetry there is no dipole.
Electric quadrupole moment
Calculated electric quadrupole moments for Na₂^- (sodium dimer anion).

References
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squib	reference	DOI
1979HUB/HER	Huber, K.P.; Herzberg, G., Molecular Spectra and Molecular Structure. IV. Constants of Diatomic Molecules,, Van Nostrand Reinhold Co., 1979
2007Iri:389	KK Irikura "Experimental Vibrational Zero-Point Energies: Diatomic Molecules" J. Phys. Chem. Ref. Data 36(2), 389, 2007	10.1063/1.2436891
JANAF	Chase, M.W., Jr.; Davies, C.A.; Downey, J.R., Jr.; Frurip, D.J.; McDonald, R.A.; Syverud, A.N., JANAF Thermochemical Tables (Third Edition), J. Phys. Chem. Ref. Data,Suppl. 1, 1985, 14, 1.
webbook	NIST Chemistry Webbook (http://webbook.nist.gov/chemistry)

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