Atomic unit of permittivity
UnitsMeasured
= 1.112 650 056 20(17) × 10−10 F m−1
- Value
- 1.112 650 056 20 × 10−10 F m−1
- Standard uncertainty
- 1.7 × 10−20 F m−1
- Relative uncertainty
- 1.5 × 10−10 (153 parts per trillion)
- Status
- Measured since 2019 (exact before)
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# atomic unit of permittivity, CODATA 2022 (NIST)
atomic_unit_of_permittivity = 1.1126500562e-10 # F m^-1, standard uncertainty 1.7e-20
# SciPy: scipy.constants.physical_constants['atomic unit of permittivity']What it is
The unit of permittivity in the Hartree system of atomic units, where the electron mass, the elementary charge, ħ and 4πε₀ are all set to 1. Its value here is the SI equivalent of one atomic unit.
Until CODATA 2014 this value was exact by definition. Since the 2019 SI redefinition it is measured, because the constant that used to fix it was replaced by a fixed elementary charge.
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 | 1.112 650 056 20(17) × 10−10 | 1.5 × 10−10 | +4.4 σ of 2018 |
| 2018 | 1.112 650 055 45(17) × 10−10 | 1.5 × 10−10 | |
| 2014 | 1.112 650 056… × 10−10 | exact | exact |
| 2010 | 1.112 650 056… × 10−10 | exact | exact |
| 2006 | 1.112 650 056… × 10−10 | exact | exact |
| 2002 | 1.112 650 056… × 10−10 | exact | exact |
| 1998 | 1.112 650 056… × 10−10 | exact |
“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).