-- CODATA Internationally recommended 2022 values -- https://physics.nist.gov/cuu/Constants/ -- a0 Bohr radius (per electron mass, not reduced electron mass) -- alpha fine structure constant -- c speed of light in vacuum -- e elementary charge -- epsilon0 vacuum electric permittivity -- h Planck constant -- hbar reduced Planck constant -- k Boltzmann constant -- me electron mass -- mp proton mass -- mu0 vacuum magnetic permeability -- c, e, h, and k are exact values a0 = 5.29177210544 10^(-11) meter alpha = 7.2973525643 10^(-3) c = 299792458.0 meter / second e = 1.602176634 10^(-19) coulomb epsilon0 = 8.8541878188 10^(-12) farad / meter h = 6.62607015 10^(-34) joule second hbar = h / float(2 pi) k = 1.380649 10^(-23) joule / kelvin me = 9.1093837139 10^(-31) kilogram mp = 1.67262192595 10^(-27) kilogram mu0 = 1.25663706127 10^(-6) newton / ampere^2 -- derived units coulomb = ampere second farad = coulomb / volt joule = kilogram meter^2 / second^2 newton = kilogram meter / second^2 tesla = kilogram / second^2 / ampere volt = joule / coulomb -- base units (for printing) ampere = "ampere" kelvin = "kelvin" kilogram = "kilogram" meter = "meter" second = "second" -- eV per joule eV = 1/e coulomb / joule "eV" -- examples "Hydrogen atom" mu = me mp / (me + mp) E1 = -mu c^2 alpha^2 / 2 E1 "In electron volts" E1 eV "Elementary charge" e sqrt(4 float(pi) epsilon0 alpha hbar c) "coulomb" / coulomb -- convert to coulombs "Speed of light" c 1 / sqrt(mu0 epsilon0) Run