# hartree

> English word · Noun

## Definitions
1. The atomic unit of energy, defined as 2R_∞hc, where R_∞ is the Rydberg constant, h is the Planck constant and c is the speed of light. It equals 4.35974 attojoules.

## Etymology
Named after the British physicist Douglas Hartree (1897–1958).

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/hartree