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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 Al2 (Aluminum diatomic)

Other names
Aluminum; dialuminum;
State Conformation
3Σg 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   10.00 kJ mol-1 1990Fu/Lem:8420
Hfg(0K) enthalpy of formation 525.90 10.00 kJ mol-1 1990Fu/Lem:8420
Entropy (298.15K) entropy 243.84 0.30 J K-1 mol-1 Gurvich
Integrated Heat Capacity (0 to 298.15K) integrated heat capacity 10.14   kJ mol-1 Gurvich
Heat Capacity (298.15K) heat capacity 37.06   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
1 Σg 286 1990Fu/Lem:8420      
Detailed diatomic data
ωe ωexe ωeye Be αe ZPE reference
285.8 0.9 0.17127 0.0008 142.6763 2007Iri:389

vibrational zero-point energy: 142.9 cm-1
Calculated vibrational frequencies for Al2 (Aluminum diatomic).
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment
  0.17127   1990Fu/Lem:8420 B0

Calculated rotational constants for Al2 (Aluminum diatomic).

Product of moments of inertia moments of inertia
98.42722amu Å2   1.634448E-38gm cm2
Geometric Data
picture of Aluminum 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
rAlAl 2.701 0.002 1 2 1990Fu/Lem:8420 re


Atom x (Å) y (Å) z (Å)
Al1 0.0000 0.0000 0.0000
Al2 0.0000 0.0000 2.7010

Atom - Atom Distances bond lengths
Distances in Å

  Al1 Al2
Al1   2.7010
Al2 2.7010  

Calculated geometries for Al2 (Aluminum diatomic).

Bond descriptions

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


Atom 1 Atom 2
Al1 Al2
Electronic energy levels (cm-1)
Energy (cm-1) Degeneracy reference description
0 4 1990Fu/Lem:8420 3Σg
30.4 2 1990Fu/Lem:8420 1Σg
63.4 3 1990Fu/Lem:8420 5Σu
17419.2 3 1990Fu/Lem:8420
24500 6 1990Fu/Lem:8420
27274.7 3 1990Fu/Lem:8420
28036 6 1990Fu/Lem:8420
30530.4 3 1990Fu/Lem:8420
31101.6 3 1990Fu/Lem:8420
32598.8 3 1990Fu/Lem:8420
34519.697 6 1990Fu/Lem:8420
38328.248 3 1990Fu/Lem:8420
38621.958 6 1990Fu/Lem:8420

Ionization Energies (eV)

Ionization Energy I.E. unc. vertical I.E. v.I.E. unc. reference Comment
5.400 1.000     webbook upper limit for EA

Electron Affinity (eV)

Electron Affinity unc. reference
1.460 0.060 2002Rie/Tsc:231
Dipole, Quadrupole and Polarizability
Electric dipole moment dipole
For a molecule with D∞h symmetry there is no dipole.
Electric quadrupole moment quadrupole
Calculated electric quadrupole moments for Al2 (Aluminum diatomic).

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squib reference DOI
1990Fu/Lem:8420 Z Fu, GW Lemire, GA Bishea, MD Morse "Spectroscopy and electronic structure fo jet-cooled Al2" J. Chem. Phys. 93(12), 8420, 1990 10.1063/1.459280
2002Rie/Tsc:231 JC Rienstra-Kiracofe, GS Tschumper, HF Schaefer III, S Nandi, GB Ellison "Atomic and Molecular Electron Affinities: Photoelectron Experiments and Theoretical Computations" Chemical Reviews 2002, 102, 231-282 10.1021/cr990044u
2007Iri:389 KK Irikura "Experimental Vibrational Zero-Point Energies: Diatomic Molecules" J. Phys. Chem. Ref. Data 36(2), 389, 2007 10.1063/1.2436891
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
webbook NIST Chemistry Webbook (  

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