Hartree units[′här·trē ‚yü·nəts]
(also atomic units), a natural system of units in which the following fundamental physical constants are set equal to unity: the charge e and mass me of the electron (e = 1.6021892 × 10–19 coulombs and me = 0.9109534 × 10–30 kg), the Bohr radius a0 = 0.52917706 × 10–10 m, and Planck’s constant ħ = h/2π = 1.0545887 ×, 10–34 joules-sec. In other words, a0 is taken as the unit of length, me is taken as the unit of mass, and the unit of time is approximately equal to 2.419 × 10–17 sec. The use of Hartree units makes it possible to simplify the equations of quantum mechanics. The units were proposed by the English physicist D. Hartree in 1928.
REFERENCESDolinskii, E. F., and B. I. Pilipchuk. “Estestvennye sistemy edinits.” In Entsiklopediia izmerenii, kontrolia i avtomatiki (EIKA), fase. 4. Moscow-Leningrad, 1965. Pages 3–8.
Burdun, G. D. Spravochnik po mezhdunarodnoi sisteme edinits. Moscow, 1971. Page 195.