Wigner_Seitz_radius
- plasmapy.formulary.quantum.Wigner_Seitz_radius(n: Quantity) Quantity[source]
Calculate the Wigner-Seitz radius, which approximates the inter-particle spacing.
This function returns the radius of a sphere whose volume is equal to the mean volume per atom in a solid. This parameter is often used to calculate the coupling parameter. When ion density is used, this is the ion sphere radius, i.e., the space occupied by a single ion with no other ions in that space. Higher density means less space for each ion, so the radius is smaller.
- Parameters:
n (
Quantity) – Particle number density.- Returns:
radius – The Wigner-Seitz radius in meters.
- Return type:
- Raises:
UnitConversionError – If argument is in incorrect units.
ValueError – If argument contains invalid values.
- Warns:
UnitsWarning– If units are not provided, SI units are assumed.
Notes
The Wigner-Seitz radius approximates the interparticle spacing. It is the radius of a sphere whose volume is equal to the mean volume per atom in a solid:
\[r = \left(\frac{3}{4 π n}\right)^{1/3}\]See also
Examples
>>> import astropy.units as u >>> Wigner_Seitz_radius(1e29 * u.m**-3) <Quantity 1.33650462e-10 m>