Hartree energy - Definition

The Hartree energy (symbol E_h) is a physical constant used as atomic unit of energy, named after physicist Douglas Hartree.

It has a value of twice the absolute value of binding energy of the electron in the ground state of the hydrogen atom |W₁| or the ionization energy.

<math>E_h = {\hbar^2 \over {m_e a^2_0}}<math>

= 4.359 743 81(34) × 10^-18 J = 27.214 4 eV = 2 Ry

where:

<math>\hbar<math> is the Dirac's constant,

<math>m_e<math> is the electron rest mass

<math>a_0<math> is the Bohr radius