National Institute of Standards and Technology
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

NIST policy on privacy, security, and accessibility.

Please rate our products
© 2013 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.

Please send questions, comments, corrections, additions and suggestions to

return to home page

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

Listing of experimental data for As2 (Arsenic diatomic)

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 221.00 15.00 kJ mol-1 1973Kor/Gin:135
Hfg(0K) enthalpy of formation   15.00 kJ mol-1 1973Kor/Gin:135
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 Σ 430 webbook      

vibrational zero-point energy: 214.8 cm-1
Calculated vibrational frequencies for As2 (Arsenic diatomic).
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment
  0.10179   webbook

Calculated rotational constants for As2 (Arsenic diatomic).

Product of moments of inertia moments of inertia
165.6118amu Å2   2.750092E-38gm cm2
Geometric Data
picture of Arsenic 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
rAsAs 2.103   1 2 webbook re


Atom x (Å) y (Å) z (Å)
As1 0.0000 0.0000 0.0000
As2 0.0000 0.0000 2.1026

Atom - Atom Distances bond lengths
Distances in Å

  As1 As2
As1   2.1026
As2 2.1026  

Calculated geometries for As2 (Arsenic diatomic).

Bond descriptions

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


Atom 1 Atom 2
As1 As2
Electronic energy levels (cm-1)
Energy (cm-1) Degeneracy reference description

Ionization Energies (eV)

Ionization Energy I.E. unc. vertical I.E. v.I.E. unc. reference
10.000 0.200     webbook

Electron Affinity (eV)

Electron Affinity unc. reference
0.739 0.008 webbook
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 As2 (Arsenic diatomic).

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
squib reference DOI
1973Kor/Gin:135 J Kordis, KA Gingerich "Atomization Energy and Standard Heat of Formation of Gaseous Diatomic Arsenic" J. Chemical and Engineering Data 18(2), 135, 1973 10.1021/je60057a023
webbook NIST Chemistry Webbook (  

Got a better number? Please email us at