rizer.misc.units

Physical constants and unit conversions.

All units are by default in the International System of Units (SI).

Attributes

e	Elementary charge [C].
k_b	Boltzmann constant [J/K].
N_a	Avogadro's number [mol^-1].
c	Speed of light [m/s].
h	Planck constant [J s].
m_e	Electron mass [kg].
M_e	Electron molar mass [kg/mol].
eV_to_K	Conversion factor from eV to K.
K_to_eV	Conversion factor from K to eV.
eV_to_J	Conversion factor from eV to J.
J_to_eV	Conversion factor from J to eV.
K_to_J	Conversion factor from K to J.
J_to_K	Conversion factor from J to K.
kJ_per_mol_to_J_per_particle	Conversion factor from kJ/mol to J/particle.
Da	Dalton or atomic mass constant [kg].
R	Ideal gas constant [J/(mol K)].
R_kmol	Ideal gas constant [J/(kmol K)].
hbar	Reduced Planck constant [J s], via scipy.constants.hbar.
epsilon_0	Vacuum permittivity [F/m].
stefan_boltzmann	Stefan-Boltzmann constant [W/(m^2 K^4)].
invcm_to_joule	Conversion factor from inverse cm to Joules.
spitzer_constant	Spitzer conductivity constant in Ohm^(-1) . m^(-1) . K^(-3/2).
bohr_radius_m	Bohr radius [m], via scipy.constants.physical_constants["Bohr radius"].
rydberg_energy_eV	Rydberg constant [eV], via scipy.constants.physical_constants["Rydberg constant times hc in eV"].

Module Contents

rizer.misc.units.e

Elementary charge [C].

CODATA value via scipy.constants.e (https://physics.nist.gov/cgi-bin/cuu/Value?e).

rizer.misc.units.k_b

Boltzmann constant [J/K].

CODATA value via scipy.constants.k (https://physics.nist.gov/cgi-bin/cuu/Value?k).

rizer.misc.units.N_a

Avogadro’s number [mol^-1].

CODATA value via scipy.constants.N_A (https://physics.nist.gov/cgi-bin/cuu/Value?na).

rizer.misc.units.c

Speed of light [m/s].

Exact value via scipy.constants.c (https://physics.nist.gov/cgi-bin/cuu/Value?c).

rizer.misc.units.h

Planck constant [J s].

CODATA value via scipy.constants.h (https://physics.nist.gov/cgi-bin/cuu/Value?h).

rizer.misc.units.m_e

Electron mass [kg].

CODATA value via scipy.constants.m_e (https://physics.nist.gov/cgi-bin/cuu/Value?me).

rizer.misc.units.M_e

Electron molar mass [kg/mol].

rizer.misc.units.eV_to_K

Conversion factor from eV to K.

rizer.misc.units.K_to_eV

Conversion factor from K to eV.

rizer.misc.units.eV_to_J

Conversion factor from eV to J.

rizer.misc.units.J_to_eV

Conversion factor from J to eV.

rizer.misc.units.K_to_J

Conversion factor from K to J.

rizer.misc.units.J_to_K

Conversion factor from J to K.

rizer.misc.units.kJ_per_mol_to_J_per_particle

Conversion factor from kJ/mol to J/particle.

rizer.misc.units.Da = 1.66053906892e-27

Dalton or atomic mass constant [kg].

Taken from https://physics.nist.gov/cgi-bin/cuu/Value?u

rizer.misc.units.R

Ideal gas constant [J/(mol K)].

CODATA value via scipy.constants.R (https://physics.nist.gov/cgi-bin/cuu/Value?r).

rizer.misc.units.R_kmol

Ideal gas constant [J/(kmol K)].

Taken from https://physics.nist.gov/cgi-bin/cuu/Value?r” and multiplied by 1000

rizer.misc.units.hbar

Reduced Planck constant [J s], via scipy.constants.hbar.

rizer.misc.units.epsilon_0

Vacuum permittivity [F/m].

CODATA value via scipy.constants.epsilon_0 (https://physics.nist.gov/cgi-bin/cuu/Value?ep0).

rizer.misc.units.stefan_boltzmann

Stefan-Boltzmann constant [W/(m^2 K^4)].

CODATA value via scipy.constants.Stefan_Boltzmann (https://physics.nist.gov/cgi-bin/cuu/Value?sigma).

rizer.misc.units.invcm_to_joule

Conversion factor from inverse cm to Joules.

rizer.misc.units.spitzer_constant

Spitzer conductivity constant in Ohm^(-1) . m^(-1) . K^(-3/2).

The conductivity of a fully-ionized plasma is given by the Spitzer conductivity:

\[\sigma = \text{Spitzer constant} \times \frac{T_e^{3/2}}{\log(\lambda)}\]

with :

• \(T_e\) the electron temperature in K,

• \(\log(\lambda)\) the Coulomb logarithm.

The constant is given by:

\[\begin{align} \text{Spitzer constant} &= \left(\frac{4 \pi \varepsilon_0}{e}\right)^2 \times \left(\frac{k_b^{3/2}}{\frac{4}{3} \sqrt{2 \pi m_e} }\right) \times 1.96 &= 1.53 \times 10^{-2} \, \Omega^{-1} \, \text{m}^{-1} \, \text{K}^{-3/2} \end{align}\]

with:

• \(\varepsilon_0\) the vacuum permittivity,

• \(e\) the elementary charge,

• \(k_b\) the Boltzmann constant,

• \(m_e\) the electron mass.

rizer.misc.units.bohr_radius_m

Bohr radius [m], via scipy.constants.physical_constants[“Bohr radius”].

rizer.misc.units.rydberg_energy_eV

Rydberg constant [eV], via scipy.constants.physical_constants[“Rydberg constant times hc in eV”].