include/celeritas/Constants.hh

0001 //---------------------------------*-CUDA-*----------------------------------//
0002 // Copyright 2020-2024 UT-Battelle, LLC, and other Celeritas developers.
0003 // See the top-level COPYRIGHT file for details.
0004 // SPDX-License-Identifier: (Apache-2.0 OR MIT)
0005 //---------------------------------------------------------------------------//
0006 //! \file celeritas/Constants.hh
0007 //! \brief Mathematical, numerical, and physical constants
0008 //---------------------------------------------------------------------------//
0009 #pragma once
0010
0011 #include "corecel/Constants.hh"
0012 #include "corecel/Types.hh"
0013
0014 #include "Units.hh"
0015
0016 namespace celeritas
0017 {
0018
0019 /*!
0020  * Mathematical, numerical, and physical constants.
0021  *
0022  * Some of the physical
0023  * constants listed here are *exact* numerical values: see the International
0024  * System of Units, 9th ed. (2019), for definition of constants and how they
0025  * relate to the different units.
0026  *
0027  * Celeritas            | CLHEP                   | Notes
0028  * -------------------- | ---------------------   | ------------
0029  * a0_bohr              | Bohr_radius             | Bohr radius
0030  * alpha_fine_structure | fine_structure_const    | |
0031  * atomic_mass          | amu                     | Not the same as 1/avogadro
0032  * eps_electric         | epsilon0                | Vacuum permittivity
0033  * h_planck             | h_Planck                | |
0034  * k_boltzmann          | k_Boltzmann             | |
0035  * mu_magnetic          | mu0                     | Vacuum permeability
0036  * na_avogadro          | Avogadro                | [1/mol]
0037  * r_electron           | classic_electr_radius   | Classical electron radius
0038  * kcd_luminous         | [none]                  | Lumens per Watt
0039  * lambdabar_electron   | electron_Compton_length | Reduced Compton wavelength
0040  * stable_decay_constant| [none]                  | Decay for a stable particle
0041  *
0042  * In the CLHEP unit system, the value of the constant \c e_electron is defined
0043  * to be 1 and \c coulomb is derivative from that. To avoid floating point
0044  * arithmetic issues that would lead to the "units" and "constants" having
0045  * different values for it, a special case redefines the value for CLHEP.
0046  *
0047  * Some experimental physical constants are derived from the other physical
0048  * constants, but for consistency and clarity they are presented numerically
0049  * with the units provided in the CODATA 2018 dataset. The \c Constants.test.cc
0050  * unit tests compare the numerical value against the derivative values inside
0051  * the celeritas unit system. All experimental values include the final
0052  * (ususally two) imprecise digits; their precision is usually on the order of
0053  * \f$ 10^{-11} \f$.
0054  */
0055 namespace constants
0056 {
0057 //---------------------------------------------------------------------------//
0058
0059 #define CELER_ICRT inline constexpr real_type
0060
0061 //!@{
0062 //! \name Physical constants with *exact* value as defined by SI
0063 CELER_ICRT c_light = 299792458. * units::meter / units::second;
0064 CELER_ICRT h_planck = 6.62607015e-34 * units::joule * units::second;
0065 #if CELERITAS_UNITS != CELERITAS_UNITS_CLHEP
0066 CELER_ICRT e_electron = 1.602176634e-19 * units::coulomb;
0067 #endif
0068 CELER_ICRT k_boltzmann = 1.380649e-23 * units::joule / units::kelvin;
0069 CELER_ICRT na_avogadro = 6.02214076e23;
0070 CELER_ICRT kcd_luminous = 683;
0071 //!@}
0072
0073 #if CELERITAS_UNITS == CELERITAS_UNITS_CLHEP
0074 //! Special case for CLHEP: electron charged is unity by definition
0075 CELER_ICRT e_electron = 1;
0076 #endif
0077
0078 //!@{
0079 //! \name Exact derivative constants
0080 CELER_ICRT hbar_planck = h_planck / (2 * pi);
0081 //!@}
0082
0083 //!@{
0084 //! \name Experimental physical constants from CODATA 2018
0085 CELER_ICRT a0_bohr = 5.29177210903e-11 * units::meter;
0086 CELER_ICRT alpha_fine_structure = 7.2973525693e-3;
0087 CELER_ICRT atomic_mass = 1.66053906660e-24 * units::gram;
0088 CELER_ICRT electron_mass = 9.1093837015e-28 * units::gram;
0089 CELER_ICRT proton_mass = 1.67262192369e-24 * units::gram;
0090 CELER_ICRT eps_electric = 8.8541878128e-12 * units::farad / units::meter;
0091 CELER_ICRT mu_magnetic = 1.25663706212e-6 * units::newton
0092                          / (units::ampere * units::ampere);
0093 CELER_ICRT r_electron = 2.8179403262e-15 * units::meter;
0094 CELER_ICRT rinf_rydberg = 10973731.568160 / units::meter;
0095 CELER_ICRT eh_hartree = 4.3597447222071e-18 / units::meter;
0096 CELER_ICRT lambdabar_electron = 3.8615926796e-13 * units::meter;
0097 //!@}
0098
0099 //!@{
0100 //! \name Other constants
0101 CELER_ICRT stable_decay_constant = 0;
0102 //!@}
0103 #undef CELER_ICRT
0104
0105 //---------------------------------------------------------------------------//
0106 }  // namespace constants
0107 }  // namespace celeritas