Hartree energy
Atomic & nuclearMeasured
= 4.359 744 722 2060(48) × 10−18 J
- Value
- 4.359 744 722 2060 × 10−18 J
- Standard uncertainty
- 4.8 × 10−30 J
- Relative uncertainty
- 1.1 × 10−12 (1.1 parts per trillion)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# Hartree energy, CODATA 2022 (NIST)
E_h = 4.359744722206e-18 # J, standard uncertainty 4.8e-30
# SciPy: scipy.constants.physical_constants['Hartree energy']What it is
The atomic unit of energy, about 27.2 eV: twice the energy needed to ionise hydrogen in the heavy-nucleus limit. Quantum chemistry programs report energies in hartrees.
Equations
- definition
In other units
| Unit | Value | |
|---|---|---|
| CGS (cm2 g s−2) | 4.359 744 722 21 × 10−11 | |
| eV electronvolt | 27.211 386 246 | |
| keV kiloelectronvolt | 0.027 211 386 246 | |
| Eₕ hartree | 1 | unit is itself measured |
| Ry rydberg | 2 | unit is itself measured |
Converted with ConstantID's unit table; digits are rounded to the precision of the value, and a long exact value is rounded only for display. The relative uncertainty is unchanged by conversion to an exactly defined unit.
How the value changed, 1998–2022
Each point is one CODATA adjustment, plotted as its difference from the 2022 value; the bars show one standard uncertainty (an arrowhead means the bar runs off the chart).
Relative uncertainty
| CODATA | Value (uncertainty) | Relative uncertainty | Change from previous |
|---|---|---|---|
| 2022 | 4.359 744 722 2060(48) × 10−18 | 1.1 × 10−12 | −0.1 σ of 2018 |
| 2018 | 4.359 744 722 2071(85) × 10−18 | 1.9 × 10−12 | +1.3 σ of 2014 |
| 2014 | 4.359 744 650(54) × 10−18 | 1.2 × 10−8 | +1.6 σ of 2010 |
| 2010 | 4.359 744 34(19) × 10−18 | 4.4 × 10−8 | +1.8 σ of 2006 |
| 2006 | 4.359 743 94(22) × 10−18 | 5.0 × 10−8 | −0.3 σ of 2002 |
| 2002 | 4.359 744 17(75) × 10−18 | 1.7 × 10−7 | +1.1 σ of 1998 |
| 1998 | 4.359 743 81(34) × 10−18 | 7.8 × 10−8 |
“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).