Hartree energy: an atomic energy scale

The hartreeEnergy constant is the Hartree energy, a natural unit of energy in atomic physics and quantum chemistry. It is approximately 4.36 × 10⁻¹⁸ joules, or about 27.2 electronvolts.

Practical use

Hartrees make electronic-structure energies compact. Convert a result with to() or choose a readable unit with toBest(). Compare it with the Planck constant in quantum formulas.

Caveat

Keep units attached through a calculation; Hartree is an energy unit, not a voltage or frequency.

Use Hartree Energy in a calculation

Enter hartreeEnergy on a calculator line to see its built-in value, or place the name inside a longer expression. Keep any displayed unit attached when converting or combining physical quantities, and check that every other value uses a compatible dimension.

The example above is editable, so you can replace surrounding values and test the constant in your own formula. Browse all constants to compare related values and notation.