The following mathematical and physical constants are available through the h module:

h.PI        3.14159265358979323846

h.E         2.71828182845904523536

h.GAMMA     0.57721566490153286060 (Euler)

h.DEG       57.29577951308232087680 (deg/radian)

h.PHI       1.61803398874989484820 (golden ratio)

h.FARADAY   96485.3321233100141 (modern value. derived from mole and electron charge)

h.R         8.3144626181532395 (modern value. derived from boltzmann constant and mole)

h.Avogadro_constant  6.02214076e23 (codata2018 value, introduced version 8.0)

As of Version 8.0 (circa October, 2020) modern units are the default.


Constants are not treated specially by the interpreter and may be changed with assignment statements. However a change of FARADAY, R, or Avogadro_constant generate a warning message (default once). Python warning messages can be managed with import warnings; warnings.filterwarnings(action) where useful actions are "error", "ignore", "always", or "once". If assignment takes place due to execution of a hoc interpreter statement, the warning occurs only once but cannot be avoided.