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Atomic units

A system of natural units for atomic physics, based on fundamental constants.

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Atomic units are a system of natural units convenient for atomic physics, computational chemistry, and atomic spectroscopy.[1] Physicist Douglas Hartree first proposed and gave a name to these units.[1]

Quick Facts

Field
  • Atomic physics
  • computational chemistry
  • atomic spectroscopy
Named by
Douglas Hartree

Facts from the source article.

Key facts and history

Hartree defined atomic units based on three physical constants: unit of length, unit of charge, and unit of mass.[1] The numeric value of the speed of light in atomic units is approximately 137 a.u..[2] Shull and Hall put forward a proposal in 1959 for atomic units that were based on Hartree's system.[3] Quantum chemistry saw widespread adoption of these terms.[4]

The reduced Planck constant, elementary charge, and electron rest mass each serve as atomic units for action, charge, and mass respectively.[5]

What the cited sources add

The 2022 CODATA recommended values give the atomic unit of action as exactly 1.054 571 817... × 10⁻³⁴ J s.[6] The 2022 CODATA recommended values give the atomic unit of charge as exactly 1.602 176 634 × 10⁻¹⁹ C.[7] The 2022 CODATA recommended values give the atomic unit of mass as 9.109 383 7139 × 10⁻³¹ kg with a relative standard uncertainty of 3.1 × 10⁻¹⁰.[8] The 9th edition of the SI Brochure, published by the BIPM in 2019, documents the International System of Units.[9]

References

  1. Wikipedia, "Atomic units" (CC BY-SA 4.0), which cites: Hartree, "The Wave Mechanics of an Atom with a Non-Coulomb Central Field. Part I. Theory and Methods", Mathematical Proceedings of the Cambridge Philosophical Society, 1928, p. 89–110 (original not read by us) en.wikipedia.org
  2. Wikipedia, "Atomic units" (CC BY-SA 4.0), which cites: Karplus, "Atoms and Molecules: An Introduction for Students of Physical Chemistry", W. A. Benjamin, 1970 (original not read by us) en.wikipedia.org
  3. Wikipedia, "Atomic units" (CC BY-SA 4.0), which cites: Shull, "Atomic Units", Nature, 1959, p. 1559 (original not read by us) en.wikipedia.org
  4. Wikipedia, "Atomic units" (CC BY-SA 4.0), which cites: Levine, "Quantum chemistry", Prentice-Hall International, 1991 (we also read that source) en.wikipedia.org
  5. Wikipedia, "Atomic units" (CC BY-SA 4.0), which cites: "atomic unit of action"; "atomic unit of charge"; "atomic unit of mass" (we also read that source) en.wikipedia.org
  6. "atomic unit of action". facts only, no text reused. physics.nist.gov
  7. "atomic unit of charge". facts only, no text reused. physics.nist.gov
  8. "atomic unit of mass". facts only, no text reused. physics.nist.gov
  9. "9th edition of the SI Brochure", BIPM, 2019. facts only, no text reused. bipm.org

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Atomic units (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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