Various physical constants now available. The values are extracted from: http://physics.nist.gov/cuu/Constants/index.htm

Symbol Description Value Unit
$$\mu$$ Atomic mass constant $$1.660539040\,.10^{-27}$$ $$kg$$
$$N_{a}$$ Avogadro constant $$6.022140857\,.10^{23}$$ $$\mathrm{mol}^{-1}$$
$$k_{b}$$ Boltzmann constant $$1.38064852\,.10^{-23}$$ $$J.K^{-1}$$
$$G_{0}$$ Conductance quantum $$7.7480917310\,.10^{-5}$$ $$S$$
$$e_{0}$$ Electric constant $$8.854187817\,.10^{-12}$$ $$F.m^{-1}$$
$$m_{e}$$ Electron mass $$9.10938356\,.10^{-31}$$ $$kg$$
$$eV$$ Electron volt $$1.6021766208\,.10^{-19}$$ $$J$$
$$e$$ Elementary charge $$1.6021766208\,.10^{-19}$$ $$C$$
$$F$$ Faraday constant $$96485.33289$$ $$C.\mathrm{mol}^{-1}$$
$$a$$ Fine-structure constant $$7.2973525664\,.10^{-3}$$
$$R$$ Molar gas constant $$8.3144598$$ $$J.\mathrm{mol}^{-1}.K^{-1}$$
$$s$$ Stefan-Boltzmann constant $$5.670367\,.10^{-8}$$ $$W.m^{-2}.K^{-4}$$

# C++

The physical constants are available as constexpr static members of tfel::PhysicalConstants class defined in the TFEL/PhysicalConstants.hxx header.

using Cste   = tfel::PhysicalConstants<real>;
const auto R = Cste::R;

# Python

The physical constants are available as members of the tfel.PhysicalConstants class, as follows:

from tfel import PhysicalConstants as Cste
print(Cste.Na)