Atomic unit of momentum
UnitsMeasured
= 1.992 851 915 45(31) × 10−24 kg m s−1
- Value
- 1.992 851 915 45 × 10−24 kg m s−1
- Standard uncertainty
- 3.1 × 10−34 kg m s−1
- Relative uncertainty
- 1.6 × 10−10 (156 parts per trillion)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# atomic unit of momentum, CODATA 2022 (NIST)
atomic_unit_of_momentum = 1.99285191545e-24 # kg m s^-1, standard uncertainty 3.1e-34
# SciPy: scipy.constants.physical_constants['atomic unit of momentum']What it is
The unit of momentum 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.
In other units
| Unit | Value | |
|---|---|---|
| CGS (cm g s−1) | 1.992 851 915 45 × 10−19 |
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 | 1.992 851 915 45(31) × 10−24 | 1.6 × 10−10 | +4.5 σ of 2018 |
| 2018 | 1.992 851 914 10(30) × 10−24 | 1.5 × 10−10 | +1.3 σ of 2014 |
| 2014 | 1.992 851 882(24) × 10−24 | 1.2 × 10−8 | +1.6 σ of 2010 |
| 2010 | 1.992 851 740(88) × 10−24 | 4.4 × 10−8 | +1.8 σ of 2006 |
| 2006 | 1.992 851 565(99) × 10−24 | 5.0 × 10−8 | −0.3 σ of 2002 |
| 2002 | 1.992 851 66(34) × 10−24 | 1.7 × 10−7 | +0.9 σ of 1998 |
| 1998 | 1.992 851 51(16) × 10−24 | 8.0 × 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).