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

Listing of experimental data for Be2 (Beryllium diatomic)

Other names
Beryllium; diberyllium;
InChI=1/2Be [Be][Be] diberyllium
State Conformation
1Σg 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 637.20 7.00 kJ mol-1 JANAF
Hfg(0K) enthalpy of formation 631.14 7.00 kJ mol-1 JANAF
Entropy (298.15K) entropy 206.40 4.00 J K-1 mol-1 JANAF
Integrated Heat Capacity (0 to 298.15K) integrated heat capacity 9.96   kJ mol-1 JANAF
Heat Capacity (298.15K) heat capacity 27.47   J K-1 mol-1 webbook
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 Be2 (Beryllium diatomic).
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment
  0.60860   1999Mar:399

Calculated rotational constants for Be2 (Beryllium diatomic).

Product of moments of inertia moments of inertia
27.69903amu Å2   4.599604E-39gm cm2

Geometric Data
picture of Beryllium 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
rBeBe 2.460   1 2 1984Bon/Eng:568 r0 value

Atom x (Å) y (Å) z (Å)
Be1 0.0000 0.0000 0.0000
Be2 0.0000 0.0000 2.4600

Atom - Atom Distances bond lengths
Distances in Å
  Be1 Be2
Be1   2.4600
Be2 2.4600  

Calculated geometries for Be2 (Beryllium diatomic).

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

Atom 1 Atom 2
Be1 Be2

Electronic energy levels (cm-1)
Energy (cm-1) Degeneracy reference description
0 1 1979HUB/HER 1Σg
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 Be2 (Beryllium diatomic).

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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  
1984Bon/Eng:568 VE Bondybey, JH English, "Laser Vaporization of beryllium: Gas phase spectrum and molecular potential of Be2" J. Chem. Phys. 80, 568, 1984 10.1063/1.446434
1999Mar:399 Martin, J. "The ground-state spectroscopic constants of Be2 revisited." Chemical Physics Letters. 303, 399-407 (1999) 10.1016/S0009-2614(99)00214-6
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 (  

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