hartree per particle
The hartree is the atomic unit of energy, 4.3597447222060 × 10⁻¹⁸ J, and one hartree per particle is 2625499.6 J/mol, or 2625.5 kJ/mol. It is what quantum chemistry codes print: total energies, orbital energies and reaction energies come out of Gaussian, ORCA or VASP in hartree and are converted to kJ/mol or eV for publication.
Watch out: Not exact. The hartree is fixed by the Rydberg constant and the electron mass, both measured, so this factor carries their uncertainty. Also watch for the rydberg, which is exactly half a hartree and appears in older solid-state work.
| 1 | 2,625.4996 |
Defined as twice the ionisation energy of hydrogen in the infinite-nuclear-mass approximation, which makes it the natural energy scale of the Schrödinger equation for an electron in a Coulomb field. Named for Douglas Hartree.
One hartree per particle in every molar energy unit
| 2,625,500 | joule per mole (J/mol) | |
| 2,625,500 | kilojoule per kilomole (kJ/kmol) | |
| 1,128,760 | BTU per pound-mole (BTU/lb-mol) | |
| 627,509 | calorie per mole (cal/mol) | |
| 2,625.5 | kilojoule per mole (kJ/mol) | |
| 627.509 | kilocalorie per mole (kcal/mol) | |
| 27.2114 | electronvolt per particle (eV/particle) | |
| 2.6255 | megajoule per mole (MJ/mol) | |
| 1 | hartree per particle (Ha/particle)this unit | |
| 0.0000272114 | megaelectronvolt per particle (MeV/particle) |