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/* Copyright 2019-2022 Andrew Myers, Luca Fedeli, Maxence Thevenet,
* Weiqun Zhang, Axel Huebl
*
* This file is part of WarpX.
*
* License: BSD-3-Clause-LBNL
*/
#ifndef ABLASTR_CONSTANT_H_
#define ABLASTR_CONSTANT_H_
#include <AMReX_REAL.H>
/** Numerical compile-time constants */
namespace ablastr::constant
{
/** Mathematical constants */
namespace math
{
using namespace amrex::literals;
//! ratio of a circle's circumference to its diameter
static constexpr amrex::Real pi = 3.14159265358979323846_rt;
//! https://tauday.com/tau-manifesto
static constexpr amrex::Real tau = 2.0_rt * pi;
} // namespace math
/** Physical constants
*
* Values are the 2018 CODATA recommended values
* https://physics.nist.gov/cuu/Constants/index.html
*
* New additions here should also be considered for addition to
* `warpx_constants` in WarpXUtil.cpp's `makeParser`, so that they're
* available in parsing and evaluation of PICMI expressions, as well
* as the corresponding Python definitions
*/
namespace SI
{
using namespace amrex::literals;
//! vacuum speed of light [m/s]
static constexpr auto c = 299'792'458._rt;
//! vacuum permittivity: dielectric permittivity of vacuum [F/m]
static constexpr auto ep0 = 8.8541878128e-12_rt;
//! vacuum permeability: magnetic permeability of vacuum = 4.0e-7 * pi [H/m]
static constexpr auto mu0 = 1.25663706212e-06_rt;
//! elementary charge [C]
static constexpr auto q_e = 1.602176634e-19_rt;
//! electron mass [kg]
static constexpr auto m_e = 9.1093837015e-31_rt;
//! proton mass [kg]
static constexpr auto m_p = 1.67262192369e-27_rt;
//! dalton: unified atomic mass unit [kg]
static constexpr auto m_u = 1.66053906660e-27_rt;
//! reduced Planck Constant = h / tau [J*s]
static constexpr auto hbar = 1.054571817e-34_rt;
//! fine-structure constant = mu0/(4*pi)*q_e*q_e*c/hbar [dimensionless]
static constexpr auto alpha = 0.007297352573748943_rt;
//! classical electron radius = 1./(4*pi*ep0) * q_e*q_e/(m_e*c*c) [m]
static constexpr auto r_e = 2.817940326204929e-15_rt;
//! xi: nonlinearity parameter of Heisenberg-Euler effective theory = (2.*alpha*alpha*ep0*ep0*hbar*hbar*hbar)/(45.*m_e*m_e*m_e*m_e*c*c*c*c*c)
static constexpr double xi = 1.3050122447005176e-52;
//! xi times c2 = xi*c*c. This should be usable for single precision instead of xi; very close to smallest float32 number possible (1.2e-38)
static constexpr auto xi_c2 = 1.1728865132395492e-35_rt;
//! Boltzmann constant (exact) [J/K]
static constexpr auto kb = 1.380649e-23_rt;
//! 1 eV in [J]
static constexpr auto eV = q_e;
//! 1 MeV in [J]
static constexpr auto MeV = q_e * 1e6_rt;
//! 1 eV/c in [kg*m/s]
static constexpr auto eV_invc = eV / c;
//! 1 MeV/c in [kg*m/s]
static constexpr auto MeV_invc = MeV / c;
//! 1 eV/c^2 in [kg]
static constexpr auto eV_invc2 = eV / (c * c);
//! 1 MeV/c^2 in [kg]
static constexpr auto MeV_invc2 = MeV / (c * c);
} // namespace SI
} // namespace ablastr::constant
#endif // ABLASTR_CONSTANT_H_
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