Hartree to eV Converter | Fast Energy Conversion

Hartree to Electron Volt (eV) Converter

Accurate atomic energy unit conversion for quantum chemistry and physics

Eₕ
eV

Quick Conversions

Conversion Formulas

Hartree to eV:

eV = Hartree × 27.211386245981

eV to Hartree:

Hartree = eV × 0.036749322175655

These values are based on NIST CODATA 2018 recommended constants, which provide the most accurate relationship between atomic energy units and electron volts.

Hartree to eV Conversion Table

Hartree (Eₕ) Electron Volt (eV)
0.001 0.027211386
0.01 0.272113862
0.1 2.721138625
0.5 13.605693123
1 27.211386246
2 54.422772492
5 136.056931230
10 272.113862460
20 544.227724920
50 1360.569312299
100 2721.138624598
1000 27211.386245981

Conversion Examples

Example 1: Converting 1 Hartree to eV

Given: 1 Hartree (Eₕ)

Calculation: 1 × 27.211386245981 = 27.211386245981 eV

Result: 1 Eₕ = 27.211386 eV

Example 2: Converting 15 Hartrees to eV

Given: 15 Hartree (Eₕ)

Calculation: 15 × 27.211386245981 = 408.170793689715 eV

Result: 15 Eₕ = 408.171 eV

Example 3: Converting 0.5 Hartree to eV

Given: 0.5 Hartree (Eₕ)

Calculation: 0.5 × 27.211386245981 = 13.6056931229905 eV

Result: 0.5 Eₕ = 13.606 eV (approximately 1 Rydberg)

Example 4: Converting 100 eV to Hartree

Given: 100 electron volts (eV)

Calculation: 100 × 0.036749322175655 = 3.6749322175655 Eₕ

Result: 100 eV = 3.675 Eₕ

What is a Hartree?

The Hartree (symbol: Eₕ or Ha), also known as Hartree energy, is the atomic unit of energy in quantum mechanics and computational chemistry. Named after British physicist Douglas Hartree, this unit represents the magnitude of the electric potential energy of a hydrogen atom in its ground state.

Physical Significance

The Hartree energy equals approximately twice the ionization energy of the hydrogen atom (by the virial theorem). It represents the electrostatic interaction energy between an electron and a proton separated by one Bohr radius.

NIST Value

The CODATA 2018 recommended value is 27.211386245981(30) eV, where the number in parentheses represents the standard uncertainty in the last two digits.

Applications

Widely used in atomic physics, quantum chemistry calculations, and computational molecular modeling where atomic units simplify mathematical expressions by setting fundamental constants to unity.

Relation to Rydberg

1 Hartree = 2 Rydberg (Ry). The Rydberg constant represents exactly half the Hartree energy and equals approximately 13.606 eV.

What is an Electron Volt (eV)?

The electron volt (eV) is a unit of energy commonly used in atomic and particle physics. One electron volt is defined as the amount of kinetic energy gained by an electron when accelerated through an electric potential difference of one volt.

Definition

1 eV = 1.602176634 × 10⁻¹⁹ joules. This value is exact since the 2019 redefinition of SI base units, where the elementary charge is now a defined constant.

Practical Use

The eV is the standard energy unit in spectroscopy, solid-state physics, and particle physics because it matches the typical energy scales of atomic and molecular processes.

Energy Scales

Chemical bonds: 1-10 eV; Visible light photons: 1.6-3.3 eV; X-rays: 100-100,000 eV; Nuclear processes: MeV (mega electron volts) to GeV (giga electron volts).

Multiples

keV (kilo): 10³ eV; MeV (mega): 10⁶ eV; GeV (giga): 10⁹ eV; TeV (tera): 10¹² eV. These are used for increasingly energetic phenomena.

Related Energy Conversions

Hartree to Joule

1 Eₕ = 4.3597447222 × 10⁻¹⁸ J

Hartree to kcal/mol

1 Eₕ = 627.509 kcal/mol

Hartree to kJ/mol

1 Eₕ = 2625.5 kJ/mol

Hartree to cm⁻¹

1 Eₕ = 219,474.63 cm⁻¹

Hartree to Kelvin

1 Eₕ = 315,775 K

Hartree to Rydberg

1 Eₕ = 2 Ry

eV to Joule

1 eV = 1.602176634 × 10⁻¹⁹ J

eV to kcal/mol

1 eV = 23.061 kcal/mol

Frequently Asked Questions

How many electron volts are in one Hartree?
One Hartree equals 27.211386245981 electron volts, according to the NIST CODATA 2018 recommended value. This conversion factor is used as the standard in scientific calculations involving atomic energy units.
Why is the Hartree used instead of electron volts in quantum chemistry?
The Hartree is part of the atomic unit system where fundamental constants like the electron mass, elementary charge, and reduced Planck constant are set to 1. This simplifies quantum mechanical equations significantly and reduces computational complexity in ab initio calculations.
What is the relationship between Hartree, Rydberg, and eV?
The relationships are: 1 Hartree = 2 Rydberg = 27.211386 eV. The Rydberg constant (approximately 13.606 eV) represents the ionization energy of hydrogen, which is exactly half the Hartree energy due to the virial theorem in quantum mechanics.
How accurate is the Hartree to eV conversion factor?
The NIST CODATA value has an uncertainty of only 30 parts per trillion (relative uncertainty of 1.1 × 10⁻¹¹). This makes it one of the most precisely determined physical constants, suitable for high-precision quantum calculations.
When should I use Hartree instead of other energy units?
Hartrees are preferred in computational quantum chemistry (DFT, Hartree-Fock methods), atomic physics calculations, and when working with atomic orbitals. Electron volts are more common in experimental spectroscopy, solid-state physics, and when discussing ionization energies or photon energies.
What physical quantity does the Hartree represent?
The Hartree represents the electric potential energy between an electron and proton separated by the Bohr radius (approximately 0.529 Ångströms). It’s approximately the negative of the ground state energy of the hydrogen atom and twice its ionization energy.
Can I convert Hartree to other energy units besides eV?
Yes, Hartree can be converted to joules (4.36 × 10⁻¹⁸ J), kilocalories per mole (627.5 kcal/mol), kilojoules per mole (2625.5 kJ/mol), wavenumbers (219,474.63 cm⁻¹), and temperature units (315,775 K). Each conversion has specific applications in different fields of physics and chemistry.
Why do different sources show slightly different conversion values?
Older sources may use previous CODATA values. The conversion factor has been refined over time with improved measurement precision. The 2018 CODATA value (27.211386245981 eV) is more accurate than older values like 27.2114 eV and should be used for current scientific work.

References

  1. NIST CODATA 2018 Internationally Recommended Values of the Fundamental Physical Constants. National Institute of Standards and Technology. Available at: https://physics.nist.gov/cgi-bin/cuu/Value?hrev
  2. Mohr, P. J., Newell, D. B., & Taylor, B. N. (2016). CODATA recommended values of the fundamental physical constants: 2014. Reviews of Modern Physics, 88(3), 035009.
  3. Tiesinga, E., Mohr, P. J., Newell, D. B., & Taylor, B. N. (2021). CODATA recommended values of the fundamental physical constants: 2018. Journal of Physical and Chemical Reference Data, 50(3), 033105.
  4. Hartree, D. R. (1928). The Wave Mechanics of an Atom with a Non-Coulomb Central Field. Mathematical Proceedings of the Cambridge Philosophical Society, 24(1), 89-110.
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