# Physical Constants

Physical constants in PSI4
Label | Value | Description
--- | --- | ---
_220_lattice_spacing_of_silicon | 1.920155714E-10 | {220} lattice spacing of silicon [m] uncertainty=0.000 0032 e-12
alpha_particle_electron_mass_ratio | 7294.29954136 | alpha particle-electron mass ratio [] uncertainty=0.000 000 24
alpha_particle_mass | 6.644657230E-27 | alpha particle mass [kg] uncertainty=0.000 000 082 e-27
alpha_particle_mass_energy_equivalent | 5.971920097E-10 | alpha particle mass energy equivalent [J] uncertainty=0.000 000 073 e-10
alpha_particle_mass_energy_equivalent_in_MeV | 3727.379378 | alpha particle mass energy equivalent in MeV [MeV] uncertainty=0.000 023
alpha_particle_mass_in_u | 4.001506179127 | alpha particle mass in u [u] uncertainty=0.000 000 000 063
alpha_particle_molar_mass | 0.004001506179127 | alpha particle molar mass [kg mol^{-1}] uncertainty=0.000 000 000 063 e-3
alpha_particle_proton_mass_ratio | 3.97259968907 | alpha particle-proton mass ratio [] uncertainty=0.000 000 000 36
Angstrom_star | 1.00001495E-10 | Angstrom star [m] uncertainty=0.000 000 90 e-10
atomic_mass_constant | 1.660539040E-27 | atomic mass constant [kg] uncertainty=0.000 000 020 e-27
atomic_mass_constant_energy_equivalent | 1.492418062E-10 | atomic mass constant energy equivalent [J] uncertainty=0.000 000 018 e-10
atomic_mass_constant_energy_equivalent_in_MeV | 931.4940954 | atomic mass constant energy equivalent in MeV [MeV] uncertainty=0.000 0057
atomic_mass_unit_electron_volt_relationship | 931494095.4 | atomic mass unit-electron volt relationship [eV] uncertainty=0.000 0057 e6
atomic_mass_unit_hartree_relationship | 34231776.902 | atomic mass unit-hartree relationship [E_h] uncertainty=0.000 000 0016 e7
atomic_mass_unit_hertz_relationship | 2.2523427206E+23 | atomic mass unit-hertz relationship [Hz] uncertainty=0.000 000 0010 e23
atomic_mass_unit_inverse_meter_relationship | 7.5130066166E+14 | atomic mass unit-inverse meter relationship [m^{-1}] uncertainty=0.000 000 0034 e14
atomic_mass_unit_joule_relationship | 1.492418062E-10 | atomic mass unit-joule relationship [J] uncertainty=0.000 000 018 e-10
atomic_mass_unit_kelvin_relationship | 1.08095438E+13 | atomic mass unit-kelvin relationship [K] uncertainty=0.000 000 62 e13
atomic_mass_unit_kilogram_relationship | 1.660539040E-27 | atomic mass unit-kilogram relationship [kg] uncertainty=0.000 000 020 e-27
atomic_unit_of_1st_hyperpolarizability | 3.206361329E-53 | atomic unit of 1st hyperpolarizability [C^3 m^3 J^{-2}] uncertainty=0.000 000 020 e-53
atomic_unit_of_2nd_hyperpolarizability | 6.235380085E-65 | atomic unit of 2nd hyperpolarizability [C^4 m^4 J^{-3}] uncertainty=0.000 000 077 e-65
atomic_unit_of_action | 1.054571800E-34 | atomic unit of action [J s] uncertainty=0.000 000 013 e-34
atomic_unit_of_charge | 1.6021766208E-19 | atomic unit of charge [C] uncertainty=0.000 000 0098 e-19
atomic_unit_of_charge_density | 1.0812023770E+12 | atomic unit of charge density [C m^{-3}] uncertainty=0.000 000 0067 e12
atomic_unit_of_current | 0.006623618183 | atomic unit of current [A] uncertainty=0.000 000 041 e-3
atomic_unit_of_electric_dipole_mom | 8.478353552E-30 | atomic unit of electric dipole mom. [C m] uncertainty=0.000 000 052 e-30
atomic_unit_of_electric_field | 5.142206707E+11 | atomic unit of electric field [V m^{-1}] uncertainty=0.000 000 032 e11
atomic_unit_of_electric_field_gradient | 9.717362356E+21 | atomic unit of electric field gradient [V m^{-2}] uncertainty=0.000 000 060 e21
atomic_unit_of_electric_polarizability | 1.6487772731E-41 | atomic unit of electric polarizability [C^2 m^2 J^{-1}] uncertainty=0.000 000 0011 e-41
atomic_unit_of_electric_potential | 27.21138602 | atomic unit of electric potential [V] uncertainty=0.000 000 17
atomic_unit_of_electric_quadrupole_mom | 4.486551484E-40 | atomic unit of electric quadrupole mom. [C m^2] uncertainty=0.000 000 028 e-40
atomic_unit_of_energy | 4.359744650E-18 | atomic unit of energy [J] uncertainty=0.000 000 054 e-18
atomic_unit_of_force | 8.23872336E-8 | atomic unit of force [N] uncertainty=0.000 000 10 e-8
atomic_unit_of_length | 5.2917721067E-11 | atomic unit of length [m] uncertainty=0.000 000 000 12 e-10
atomic_unit_of_mag_dipole_mom | 1.854801999E-23 | atomic unit of mag. dipole mom. [J T^{-1}] uncertainty=0.000 000 011 e-23
atomic_unit_of_mag_flux_density | 235051.7550 | atomic unit of mag. flux density [T] uncertainty=0.000 000 014 e5
atomic_unit_of_magnetizability | 7.8910365886E-29 | atomic unit of magnetizability [J T^{-2}] uncertainty=0.000 000 0090 e-29
atomic_unit_of_mass | 9.10938356E-31 | atomic unit of mass [kg] uncertainty=0.000 000 11 e-31
atomic_unit_of_momum | 1.992851882E-24 | atomic unit of mom.um [kg m s^{-1}] uncertainty=0.000 000 024 e-24
atomic_unit_of_permittivity | 1.112650056E-10 | atomic unit of permittivity [F m^{-1}] uncertainty=(exact)
atomic_unit_of_time | 2.418884326509E-17 | atomic unit of time [s] uncertainty=0.000 000 000 014 e-17
atomic_unit_of_velocity | 2187691.26277 | atomic unit of velocity [m s^{-1}] uncertainty=0.000 000 000 50 e6
Avogadro_constant | 6.022140857E+23 | Avogadro constant [mol^{-1}] uncertainty=0.000 000 074 e23
Bohr_magneton | 9.274009994E-24 | Bohr magneton [J T^{-1}] uncertainty=0.000 0057 e-26
Bohr_magneton_in_eVpT | 0.000057883818012 | Bohr magneton in eV/T [eV T^{-1}] uncertainty=0.000 000 0026 e-5
Bohr_magneton_in_HzpT | 13996245042 | Bohr magneton in Hz/T [Hz T^{-1}] uncertainty=0.000 000 086 e9
Bohr_magneton_in_inverse_meters_per_tesla | 46.68644814 | Bohr magneton in inverse meters per tesla [m^{-1} T^{-1}] uncertainty=0.000 000 29
Bohr_magneton_in_KpT | 0.67171405 | Bohr magneton in K/T [K T^{-1}] uncertainty=0.000 000 39
Bohr_radius | 5.2917721067E-11 | Bohr radius [m] uncertainty=0.000 000 000 12 e-10
Boltzmann_constant | 1.38064852E-23 | Boltzmann constant [J K^{-1}] uncertainty=0.000 000 79 e-23
Boltzmann_constant_in_eVpK | 0.000086173303 | Boltzmann constant in eV/K [eV K^{-1}] uncertainty=0.000 0050 e-5
Boltzmann_constant_in_HzpK | 2.0836612E+10 | Boltzmann constant in Hz/K [Hz K^{-1}] uncertainty=0.000 0012 e10
Boltzmann_constant_in_inverse_meters_per_kelvin | 69.503457 | Boltzmann constant in inverse meters per kelvin [m^{-1} K^{-1}] uncertainty=0.000 040
characteristic_impedance_of_vacuum | 376.730313461 | characteristic impedance of vacuum [ohm] uncertainty=(exact)
classical_electron_radius | 2.8179403227E-15 | classical electron radius [m] uncertainty=0.000 000 0019 e-15
Compton_wavelength | 2.4263102367E-12 | Compton wavelength [m] uncertainty=0.000 000 0011 e-12
Compton_wavelength_over_2_pi | 3.8615926764E-13 | Compton wavelength over 2 pi [m] uncertainty=0.000 000 18 e-15
conductance_quantum | 0.000077480917310 | conductance quantum [S] uncertainty=0.000 000 0018 e-5
conventional_value_of_Josephson_constant | 4.835979E+14 | conventional value of Josephson constant [Hz V^{-1}] uncertainty=(exact)
conventional_value_of_von_Klitzing_constant | 25812.807 | conventional value of von Klitzing constant [ohm] uncertainty=(exact)
Cu_x_unit | 1.00207697E-13 | Cu x unit [m] uncertainty=0.000 000 28 e-13
deuteron_electron_mag_mom_ratio | -0.0004664345535 | deuteron-electron mag. mom. ratio [] uncertainty=0.000 000 026 e-4
deuteron_electron_mass_ratio | 3670.48296785 | deuteron-electron mass ratio [] uncertainty=0.000 000 13
deuteron_g_factor | 0.8574382311 | deuteron g factor [] uncertainty=0.000 000 0048
deuteron_mag_mom | 4.330735040E-27 | deuteron mag. mom. [J T^{-1}] uncertainty=0.000 000 0036 e-26
deuteron_mag_mom_to_Bohr_magneton_ratio | 0.0004669754554 | deuteron mag. mom. to Bohr magneton ratio [] uncertainty=0.000 000 0026 e-3
deuteron_mag_mom_to_nuclear_magneton_ratio | 0.8574382311 | deuteron mag. mom. to nuclear magneton ratio [] uncertainty=0.000 000 0048
deuteron_mass | 3.343583719E-27 | deuteron mass [kg] uncertainty=0.000 000 041 e-27
deuteron_mass_energy_equivalent | 3.005063183E-10 | deuteron mass energy equivalent [J] uncertainty=0.000 000 037 e-10
deuteron_mass_energy_equivalent_in_MeV | 1875.612928 | deuteron mass energy equivalent in MeV [MeV] uncertainty=0.000 012
deuteron_mass_in_u | 2.013553212745 | deuteron mass in u [u] uncertainty=0.000 000 000 040
deuteron_molar_mass | 0.002013553212745 | deuteron molar mass [kg mol^{-1}] uncertainty=0.000 000 000 040 e-3
deuteron_neutron_mag_mom_ratio | -0.44820652 | deuteron-neutron mag. mom. ratio [] uncertainty=0.000 000 11
deuteron_proton_mag_mom_ratio | 0.3070122077 | deuteron-proton mag. mom. ratio [] uncertainty=0.000 000 0015
deuteron_proton_mass_ratio | 1.99900750087 | deuteron-proton mass ratio [] uncertainty=0.000 000 000 19
deuteron_rms_charge_radius | 2.1413E-15 | deuteron rms charge radius [m] uncertainty=0.0025 e-15
electric_constant | 8.854187817E-12 | electric constant [F m^{-1}] uncertainty=(exact)
electron_charge_to_mass_quotient | -1.758820024E+11 | electron charge to mass quotient [C kg^{-1}] uncertainty=0.000 000 011 e11
electron_deuteron_mag_mom_ratio | -2143.923499 | electron-deuteron mag. mom. ratio [] uncertainty=0.000 012
electron_deuteron_mass_ratio | 0.0002724437107484 | electron-deuteron mass ratio [] uncertainty=0.000 000 000 096 e-4
electron_g_factor | -2.00231930436182 | electron g factor [] uncertainty=0.000 000 000 000 52
electron_gyromag_ratio | 1.760859644E+11 | electron gyromag. ratio [s^{-1} T^{-1}] uncertainty=0.000 000 011 e11
electron_gyromag_ratio_over_2_pi | 28024.95164 | electron gyromag. ratio over 2 pi [MHz T^{-1}] uncertainty=0.000 17
electron_helion_mass_ratio | 0.0001819543074854 | electron-helion mass ratio [] uncertainty=0.000 000 000 088 e-4
electron_mag_mom | -9.284764620E-24 | electron mag. mom. [J T^{-1}] uncertainty=0.000 0057 e-26
electron_mag_mom_anomaly | 0.00115965218091 | electron mag. mom. anomaly [] uncertainty=0.000 000 000 26 e-3
electron_mag_mom_to_Bohr_magneton_ratio | -1.00115965218091 | electron mag. mom. to Bohr magneton ratio [] uncertainty=0.000 000 000 000 26
electron_mag_mom_to_nuclear_magneton_ratio | -1838.28197234 | electron mag. mom. to nuclear magneton ratio [] uncertainty=0.000 000 17
electron_mass | 9.10938356E-31 | electron mass [kg] uncertainty=0.000 000 11 e-31
electron_mass_energy_equivalent | 8.18710565E-14 | electron mass energy equivalent [J] uncertainty=0.000 000 10 e-14
electron_mass_energy_equivalent_in_MeV | 0.5109989461 | electron mass energy equivalent in MeV [MeV] uncertainty=0.000 000 0031
electron_mass_in_u | 0.000548579909070 | electron mass in u [u] uncertainty=0.000 000 000 16 e-4
electron_molar_mass | 5.48579909070E-7 | electron molar mass [kg mol^{-1}] uncertainty=0.000 000 000 16 e-7
electron_muon_mag_mom_ratio | 206.7669880 | electron-muon mag. mom. ratio [] uncertainty=0.000 0046
electron_muon_mass_ratio | 0.00483633170 | electron-muon mass ratio [] uncertainty=0.000 000 11 e-3
electron_neutron_mag_mom_ratio | 960.92050 | electron-neutron mag. mom. ratio [] uncertainty=0.000 23
electron_neutron_mass_ratio | 0.00054386734428 | electron-neutron mass ratio [] uncertainty=0.000 000 0027 e-4
electron_proton_mag_mom_ratio | -658.2106866 | electron-proton mag. mom. ratio [] uncertainty=0.000 0020
electron_proton_mass_ratio | 0.000544617021352 | electron-proton mass ratio [] uncertainty=0.000 000 000 52 e-4
electron_tau_mass_ratio | 0.000287592 | electron-tau mass ratio [] uncertainty=0.000 26 e-4
electron_to_alpha_particle_mass_ratio | 0.0001370933554798 | electron to alpha particle mass ratio [] uncertainty=0.000 000 000 045 e-4
electron_to_shielded_helion_mag_mom_ratio | 864.058257 | electron to shielded helion mag. mom. ratio [] uncertainty=0.000 010
electron_to_shielded_proton_mag_mom_ratio | -658.2275971 | electron to shielded proton mag. mom. ratio [] uncertainty=0.000 0072
electron_triton_mass_ratio | 0.0001819200062203 | electron-triton mass ratio [] uncertainty=0.000 000 000 084 e-4
electron_volt | 1.6021766208E-19 | electron volt [J] uncertainty=0.000 000 0098 e-19
electron_volt_atomic_mass_unit_relationship | 1.0735441105E-9 | electron volt-atomic mass unit relationship [u] uncertainty=0.000 000 0066 e-9
electron_volt_hartree_relationship | 0.03674932248 | electron volt-hartree relationship [E_h] uncertainty=0.000 000 023 e-2
electron_volt_hertz_relationship | 2.417989262E+14 | electron volt-hertz relationship [Hz] uncertainty=0.000 000 015 e14
electron_volt_inverse_meter_relationship | 806554.4005 | electron volt-inverse meter relationship [m^{-1}] uncertainty=0.000 000 050 e5
electron_volt_joule_relationship | 1.6021766208E-19 | electron volt-joule relationship [J] uncertainty=0.000 000 0098 e-19
electron_volt_kelvin_relationship | 11604.5221 | electron volt-kelvin relationship [K] uncertainty=0.000 000 67 e4
electron_volt_kilogram_relationship | 1.782661907E-36 | electron volt-kilogram relationship [kg] uncertainty=0.000 000 011 e-36
elementary_charge | 1.6021766208E-19 | elementary charge [C] uncertainty=0.000 000 0098 e-19
elementary_charge_over_h | 2.417989262E+14 | elementary charge over h [A J^{-1}] uncertainty=0.000 000 015 e14
Faraday_constant | 96485.33289 | Faraday constant [C mol^{-1}] uncertainty=0.000 59
Faraday_constant_for_conventional_electric_current | 96485.3251 | Faraday constant for conventional electric current [C_{90} mol^{-1}] uncertainty=0.0012
Fermi_coupling_constant | 0.000011663787 | Fermi coupling constant [GeV^{-2}] uncertainty=0.000 0006 e-5
fine_structure_constant | 0.0072973525664 | fine-structure constant [] uncertainty=0.000 000 0017 e-3
first_radiation_constant | 3.741771790E-16 | first radiation constant [W m^2] uncertainty=0.000 000 046 e-16
first_radiation_constant_for_spectral_radiance | 1.191042953E-16 | first radiation constant for spectral radiance [W m^2 sr^{-1}] uncertainty=0.000 000 015 e-16
hartree_atomic_mass_unit_relationship | 2.9212623197E-8 | hartree-atomic mass unit relationship [u] uncertainty=0.000 000 0013 e-8
hartree_electron_volt_relationship | 27.21138602 | hartree-electron volt relationship [eV] uncertainty=0.000 000 17
Hartree_energy | 4.359744650E-18 | Hartree energy [J] uncertainty=0.000 000 054 e-18
Hartree_energy_in_eV | 27.21138602 | Hartree energy in eV [eV] uncertainty=0.000 000 17
hartree_hertz_relationship | 6.579683920711E+15 | hartree-hertz relationship [Hz] uncertainty=0.000 000 000 039 e15
hartree_inverse_meter_relationship | 21947463.13702 | hartree-inverse meter relationship [m^{-1}] uncertainty=0.000 000 000 013 e7
hartree_joule_relationship | 4.359744650E-18 | hartree-joule relationship [J] uncertainty=0.000 000 054 e-18
hartree_kelvin_relationship | 315775.13 | hartree-kelvin relationship [K] uncertainty=0.000 0018 e5
hartree_kilogram_relationship | 4.850870129E-35 | hartree-kilogram relationship [kg] uncertainty=0.000 000 060 e-35
helion_electron_mass_ratio | 5495.88527922 | helion-electron mass ratio [] uncertainty=0.000 000 27
helion_g_factor | -4.255250616 | helion g factor [] uncertainty=0.000 000 050
helion_mag_mom | -1.074617522E-26 | helion mag. mom. [J T^{-1}] uncertainty=0.000 000 014 e-26
helion_mag_mom_to_Bohr_magneton_ratio | -0.001158740958 | helion mag. mom. to Bohr magneton ratio [] uncertainty=0.000 000 014 e-3
helion_mag_mom_to_nuclear_magneton_ratio | -2.127625308 | helion mag. mom. to nuclear magneton ratio [] uncertainty=0.000 000 025
helion_mass | 5.006412700E-27 | helion mass [kg] uncertainty=0.000 000 062 e-27
helion_mass_energy_equivalent | 4.499539341E-10 | helion mass energy equivalent [J] uncertainty=0.000 000 055 e-10
helion_mass_energy_equivalent_in_MeV | 2808.391586 | helion mass energy equivalent in MeV [MeV] uncertainty=0.000 017
helion_mass_in_u | 3.01493224673 | helion mass in u [u] uncertainty=0.000 000 000 12
helion_molar_mass | 0.00301493224673 | helion molar mass [kg mol^{-1}] uncertainty=0.000 000 000 12 e-3
helion_proton_mass_ratio | 2.99315267046 | helion-proton mass ratio [] uncertainty=0.000 000 000 29
hertz_atomic_mass_unit_relationship | 4.4398216616E-24 | hertz-atomic mass unit relationship [u] uncertainty=0.000 000 0020 e-24
hertz_electron_volt_relationship | 4.135667662E-15 | hertz-electron volt relationship [eV] uncertainty=0.000 000 025 e-15
hertz_hartree_relationship | 1.5198298460088E-16 | hertz-hartree relationship [E_h] uncertainty=0.000 000 000 0090 e-16
hertz_inverse_meter_relationship | 3.335640951E-9 | hertz-inverse meter relationship [m^{-1}] uncertainty=(exact)
hertz_joule_relationship | 6.626070040E-34 | hertz-joule relationship [J] uncertainty=0.000 000 081 e-34
hertz_kelvin_relationship | 4.7992447E-11 | hertz-kelvin relationship [K] uncertainty=0.000 0028 e-11
hertz_kilogram_relationship | 7.372497201E-51 | hertz-kilogram relationship [kg] uncertainty=0.000 000 091 e-51
inverse_fine_structure_constant | 137.035999139 | inverse fine-structure constant [] uncertainty=0.000 000 031
inverse_meter_atomic_mass_unit_relationship | 1.33102504900E-15 | inverse meter-atomic mass unit relationship [u] uncertainty=0.000 000 000 61 e-15
inverse_meter_electron_volt_relationship | 0.0000012398419739 | inverse meter-electron volt relationship [eV] uncertainty=0.000 000 0076 e-6
inverse_meter_hartree_relationship | 4.556335252767E-8 | inverse meter-hartree relationship [E_h] uncertainty=0.000 000 000 027 e-8
inverse_meter_hertz_relationship | 299792458 | inverse meter-hertz relationship [Hz] uncertainty=(exact)
inverse_meter_joule_relationship | 1.986445824E-25 | inverse meter-joule relationship [J] uncertainty=0.000 000 024 e-25
inverse_meter_kelvin_relationship | 0.0143877736 | inverse meter-kelvin relationship [K] uncertainty=0.000 000 83 e-2
inverse_meter_kilogram_relationship | 2.210219057E-42 | inverse meter-kilogram relationship [kg] uncertainty=0.000 000 027 e-42
inverse_of_conductance_quantum | 12906.4037278 | inverse of conductance quantum [ohm] uncertainty=0.000 0029
Josephson_constant | 4.835978525E+14 | Josephson constant [Hz V^{-1}] uncertainty=0.0030 e9
joule_atomic_mass_unit_relationship | 6700535363 | joule-atomic mass unit relationship [u] uncertainty=0.000 000 082 e9
joule_electron_volt_relationship | 6.241509126E+18 | joule-electron volt relationship [eV] uncertainty=0.000 000 038 e18
joule_hartree_relationship | 2.293712317E+17 | joule-hartree relationship [E_h] uncertainty=0.000 000 028 e17
joule_hertz_relationship | 1.509190205E+33 | joule-hertz relationship [Hz] uncertainty=0.000 000 019 e33
joule_inverse_meter_relationship | 5.034116651E+24 | joule-inverse meter relationship [m^{-1}] uncertainty=0.000 000 062 e24
joule_kelvin_relationship | 7.2429731E+22 | joule-kelvin relationship [K] uncertainty=0.000 0042 e22
joule_kilogram_relationship | 1.112650056E-17 | joule-kilogram relationship [kg] uncertainty=(exact)
kelvin_atomic_mass_unit_relationship | 9.2510842E-14 | kelvin-atomic mass unit relationship [u] uncertainty=0.000 0053 e-14
kelvin_electron_volt_relationship | 0.000086173303 | kelvin-electron volt relationship [eV] uncertainty=0.000 0050 e-5
kelvin_hartree_relationship | 0.0000031668105 | kelvin-hartree relationship [E_h] uncertainty=0.000 0018 e-6
kelvin_hertz_relationship | 2.0836612E+10 | kelvin-hertz relationship [Hz] uncertainty=0.000 0012 e10
kelvin_inverse_meter_relationship | 69.503457 | kelvin-inverse meter relationship [m^{-1}] uncertainty=0.000 040
kelvin_joule_relationship | 1.38064852E-23 | kelvin-joule relationship [J] uncertainty=0.000 000 79 e-23
kelvin_kilogram_relationship | 1.53617865E-40 | kelvin-kilogram relationship [kg] uncertainty=0.000 000 88 e-40
kilogram_atomic_mass_unit_relationship | 6.022140857E+26 | kilogram-atomic mass unit relationship [u] uncertainty=0.000 000 074 e26
kilogram_electron_volt_relationship | 5.609588650E+35 | kilogram-electron volt relationship [eV] uncertainty=0.000 000 034 e35
kilogram_hartree_relationship | 2.061485823E+34 | kilogram-hartree relationship [E_h] uncertainty=0.000 000 025 e34
kilogram_hertz_relationship | 1.356392512E+50 | kilogram-hertz relationship [Hz] uncertainty=0.000 000 017 e50
kilogram_inverse_meter_relationship | 4.524438411E+41 | kilogram-inverse meter relationship [m^{-1}] uncertainty=0.000 000 056 e41
kilogram_joule_relationship | 8.987551787E+16 | kilogram-joule relationship [J] uncertainty=(exact)
kilogram_kelvin_relationship | 6.5096595E+39 | kilogram-kelvin relationship [K] uncertainty=0.000 0037 e39
lattice_parameter_of_silicon | 5.431020504E-10 | lattice parameter of silicon [m] uncertainty=0.000 0089 e-12
Loschmidt_constant_27315_K_100_kPa | 2.6516467E+25 | Loschmidt constant (273.15 K, 100 kPa) [m^{-3}] uncertainty=0.000 0015 e25
Loschmidt_constant_27315_K_101325_kPa | 2.6867811E+25 | Loschmidt constant (273.15 K, 101.325 kPa) [m^{-3}] uncertainty=0.000 0015 e25
mag_constant | 0.0000012566370614 | mag. constant [N A^{-2}] uncertainty=(exact)
mag_flux_quantum | 2.067833831E-15 | mag. flux quantum [Wb] uncertainty=0.000 000 013 e-15
molar_gas_constant | 8.3144598 | molar gas constant [J mol^{-1} K^{-1}] uncertainty=0.000 0048
molar_mass_constant | 0.001 | molar mass constant [kg mol^{-1}] uncertainty=(exact)
molar_mass_of_carbon_12 | 0.012 | molar mass of carbon-12 [kg mol^{-1}] uncertainty=(exact)
molar_Planck_constant | 3.9903127110E-10 | molar Planck constant [J s mol^{-1}] uncertainty=0.000 000 0018 e-10
molar_Planck_constant_times_c | 0.119626565582 | molar Planck constant times c [J m mol^{-1}] uncertainty=0.000 000 000 054
molar_volume_of_ideal_gas_27315_K_100_kPa | 0.022710947 | molar volume of ideal gas (273.15 K, 100 kPa) [m^3 mol^{-1}] uncertainty=0.000 013 e-3
molar_volume_of_ideal_gas_27315_K_101325_kPa | 0.022413962 | molar volume of ideal gas (273.15 K, 101.325 kPa) [m^3 mol^{-1}] uncertainty=0.000 013 e-3
molar_volume_of_silicon | 0.00001205883214 | molar volume of silicon [m^3 mol^{-1}] uncertainty=0.000 000 61 e-6
Mo_x_unit | 1.00209952E-13 | Mo x unit [m] uncertainty=0.000 000 53 e-13
muon_Compton_wavelength | 1.173444111E-14 | muon Compton wavelength [m] uncertainty=0.000 000 26 e-15
muon_Compton_wavelength_over_2_pi | 1.867594308E-15 | muon Compton wavelength over 2 pi [m] uncertainty=0.000 000 042 e-15
muon_electron_mass_ratio | 206.7682826 | muon-electron mass ratio [] uncertainty=0.000 0046
muon_g_factor | -2.0023318418 | muon g factor [] uncertainty=0.000 000 0013
muon_mag_mom | -4.49044826E-26 | muon mag. mom. [J T^{-1}] uncertainty=0.000 000 10 e-26
muon_mag_mom_anomaly | 0.00116592089 | muon mag. mom. anomaly [] uncertainty=0.000 000 63 e-3
muon_mag_mom_to_Bohr_magneton_ratio | -0.00484197048 | muon mag. mom. to Bohr magneton ratio [] uncertainty=0.000 000 11 e-3
muon_mag_mom_to_nuclear_magneton_ratio | -8.89059705 | muon mag. mom. to nuclear magneton ratio [] uncertainty=0.000 000 20
muon_mass | 1.883531594E-28 | muon mass [kg] uncertainty=0.000 000 048 e-28
muon_mass_energy_equivalent | 1.692833774E-11 | muon mass energy equivalent [J] uncertainty=0.000 000 043 e-11
muon_mass_energy_equivalent_in_MeV | 105.6583745 | muon mass energy equivalent in MeV [MeV] uncertainty=0.000 0024
muon_mass_in_u | 0.1134289257 | muon mass in u [u] uncertainty=0.000 000 0025
muon_molar_mass | 0.0001134289257 | muon molar mass [kg mol^{-1}] uncertainty=0.000 000 0025 e-3
muon_neutron_mass_ratio | 0.1124545167 | muon-neutron mass ratio [] uncertainty=0.000 000 0025
muon_proton_mag_mom_ratio | -3.183345142 | muon-proton mag. mom. ratio [] uncertainty=0.000 000 071
muon_proton_mass_ratio | 0.1126095262 | muon-proton mass ratio [] uncertainty=0.000 000 0025
muon_tau_mass_ratio | 0.0594649 | muon-tau mass ratio [] uncertainty=0.000 54 e-2
natural_unit_of_action | 1.054571800E-34 | natural unit of action [J s] uncertainty=0.000 000 013 e-34
natural_unit_of_action_in_eV_s | 6.582119514E-16 | natural unit of action in eV s [eV s] uncertainty=0.000 000 040 e-16
natural_unit_of_energy | 8.18710565E-14 | natural unit of energy [J] uncertainty=0.000 000 10 e-14
natural_unit_of_energy_in_MeV | 0.5109989461 | natural unit of energy in MeV [MeV] uncertainty=0.000 000 0031
natural_unit_of_length | 3.8615926764E-13 | natural unit of length [m] uncertainty=0.000 000 18 e-15
natural_unit_of_mass | 9.10938356E-31 | natural unit of mass [kg] uncertainty=0.000 000 11 e-31
natural_unit_of_momum | 2.730924488E-22 | natural unit of mom.um [kg m s^{-1}] uncertainty=0.000 000 034 e-22
natural_unit_of_momum_in_MeVpc | 0.5109989461 | natural unit of mom.um in MeV/c [MeV/c] uncertainty=0.000 000 0031
natural_unit_of_time | 1.28808866712E-21 | natural unit of time [s] uncertainty=0.000 000 000 58 e-21
natural_unit_of_velocity | 299792458 | natural unit of velocity [m s^{-1}] uncertainty=(exact)
neutron_Compton_wavelength | 1.31959090481E-15 | neutron Compton wavelength [m] uncertainty=0.000 000 000 88 e-15
neutron_Compton_wavelength_over_2_pi | 2.1001941536E-16 | neutron Compton wavelength over 2 pi [m] uncertainty=0.000 000 000 14 e-15
neutron_electron_mag_mom_ratio | 0.00104066882 | neutron-electron mag. mom. ratio [] uncertainty=0.000 000 25 e-3
neutron_electron_mass_ratio | 1838.68366158 | neutron-electron mass ratio [] uncertainty=0.000 000 90
neutron_g_factor | -3.82608545 | neutron g factor [] uncertainty=0.000 000 90
neutron_gyromag_ratio | 183247172 | neutron gyromag. ratio [s^{-1} T^{-1}] uncertainty=0.000 000 43 e8
neutron_gyromag_ratio_over_2_pi | 29.1646933 | neutron gyromag. ratio over 2 pi [MHz T^{-1}] uncertainty=0.000 0069
neutron_mag_mom | -9.6623650E-27 | neutron mag. mom. [J T^{-1}] uncertainty=0.000 000 23 e-26
neutron_mag_mom_to_Bohr_magneton_ratio | -0.00104187563 | neutron mag. mom. to Bohr magneton ratio [] uncertainty=0.000 000 25 e-3
neutron_mag_mom_to_nuclear_magneton_ratio | -1.91304273 | neutron mag. mom. to nuclear magneton ratio [] uncertainty=0.000 000 45
neutron_mass | 1.674927471E-27 | neutron mass [kg] uncertainty=0.000 000 021 e-27
neutron_mass_energy_equivalent | 1.505349739E-10 | neutron mass energy equivalent [J] uncertainty=0.000 000 019 e-10
neutron_mass_energy_equivalent_in_MeV | 939.5654133 | neutron mass energy equivalent in MeV [MeV] uncertainty=0.000 0058
neutron_mass_in_u | 1.00866491588 | neutron mass in u [u] uncertainty=0.000 000 000 49
neutron_molar_mass | 0.00100866491588 | neutron molar mass [kg mol^{-1}] uncertainty=0.000 000 000 49 e-3
neutron_muon_mass_ratio | 8.89248408 | neutron-muon mass ratio [] uncertainty=0.000 000 20
neutron_proton_mag_mom_ratio | -0.68497934 | neutron-proton mag. mom. ratio [] uncertainty=0.000 000 16
neutron_proton_mass_difference | 2.30557377E-30 | neutron-proton mass difference [] uncertainty=0.000 000 85 e-30
neutron_proton_mass_difference_energy_equivalent | 2.07214637E-13 | neutron-proton mass difference energy equivalent [] uncertainty=0.000 000 76 e-13
neutron_proton_mass_difference_energy_equivalent_in_MeV | 1.29333205 | neutron-proton mass difference energy equivalent in MeV [] uncertainty=0.000 000 48
neutron_proton_mass_difference_in_u | 0.00138844900 | neutron-proton mass difference in u [] uncertainty=0.000 000 000 51
neutron_proton_mass_ratio | 1.00137841898 | neutron-proton mass ratio [] uncertainty=0.000 000 000 51
neutron_tau_mass_ratio | 0.528790 | neutron-tau mass ratio [] uncertainty=0.000 048
neutron_to_shielded_proton_mag_mom_ratio | -0.68499694 | neutron to shielded proton mag. mom. ratio [] uncertainty=0.000 000 16
Newtonian_constant_of_gravitation | 6.67408E-11 | Newtonian constant of gravitation [m^3 kg^{-1} s^{-2}] uncertainty=0.000 31 e-11
Newtonian_constant_of_gravitation_over_h_bar_c | 6.70861E-39 | Newtonian constant of gravitation over h-bar c [(GeV/c^2)^-2] uncertainty=0.000 31 e-39
nuclear_magneton | 5.050783699E-27 | nuclear magneton [J T^{-1}] uncertainty=0.000 000 031 e-27
nuclear_magneton_in_eVpT | 3.1524512550E-8 | nuclear magneton in eV/T [eV T^{-1}] uncertainty=0.000 000 0015 e-8
nuclear_magneton_in_inverse_meters_per_tesla | 0.02542623432 | nuclear magneton in inverse meters per tesla [m^{-1} T^{-1}] uncertainty=0.000 000 016 e-2
nuclear_magneton_in_KpT | 0.00036582690 | nuclear magneton in K/T [K T^{-1}] uncertainty=0.000 0021 e-4
nuclear_magneton_in_MHzpT | 7.622593285 | nuclear magneton in MHz/T [MHz T^{-1}] uncertainty=0.000 000 047
Planck_constant | 6.626070040E-34 | Planck constant [J s] uncertainty=0.000 000 081 e-34
Planck_constant_in_eV_s | 4.135667662E-15 | Planck constant in eV s [eV s] uncertainty=0.000 000 025 e-15
Planck_constant_over_2_pi | 1.054571800E-34 | Planck constant over 2 pi [J s] uncertainty=0.000 000 013 e-34
Planck_constant_over_2_pi_in_eV_s | 6.582119514E-16 | Planck constant over 2 pi in eV s [eV s] uncertainty=0.000 000 040 e-16
Planck_constant_over_2_pi_times_c_in_MeV_fm | 197.3269788 | Planck constant over 2 pi times c in MeV fm [MeV fm] uncertainty=0.000 0012
Planck_length | 1.616229E-35 | Planck length [m] uncertainty=0.000 038 e-35
Planck_mass | 2.176470E-8 | Planck mass [kg] uncertainty=0.000 051 e-8
Planck_mass_energy_equivalent_in_GeV | 1.220910E+19 | Planck mass energy equivalent in GeV [GeV] uncertainty=0.000 029 e19
Planck_temperature | 1.416808E+32 | Planck temperature [K] uncertainty=0.000 033 e32
Planck_time | 5.39116E-44 | Planck time [s] uncertainty=0.000 13 e-44
proton_charge_to_mass_quotient | 95788332.26 | proton charge to mass quotient [C kg^{-1}] uncertainty=0.000 000 059 e7
proton_Compton_wavelength | 1.32140985396E-15 | proton Compton wavelength [m] uncertainty=0.000 000 000 61 e-15
proton_Compton_wavelength_over_2_pi | 2.10308910109E-16 | proton Compton wavelength over 2 pi [m] uncertainty=0.000 000 000 097 e-15
proton_electron_mass_ratio | 1836.15267389 | proton-electron mass ratio [] uncertainty=0.000 000 17
proton_g_factor | 5.585694702 | proton g factor [] uncertainty=0.000 000 017
proton_gyromag_ratio | 267522190.0 | proton gyromag. ratio [s^{-1} T^{-1}] uncertainty=0.000 000 018 e8
proton_gyromag_ratio_over_2_pi | 42.57747892 | proton gyromag. ratio over 2 pi [MHz T^{-1}] uncertainty=0.000 000 29
proton_mag_mom | 1.4106067873E-26 | proton mag. mom. [J T^{-1}] uncertainty=0.000 000 0097 e-26
proton_mag_mom_to_Bohr_magneton_ratio | 0.0015210322053 | proton mag. mom. to Bohr magneton ratio [] uncertainty=0.000 000 0046 e-3
proton_mag_mom_to_nuclear_magneton_ratio | 2.7928473508 | proton mag. mom. to nuclear magneton ratio [] uncertainty=0.000 000 0085
proton_mag_shielding_correction | 0.000025691 | proton mag. shielding correction [] uncertainty=0.011 e-6
proton_mass | 1.672621898E-27 | proton mass [kg] uncertainty=0.000 000 021 e-27
proton_mass_energy_equivalent | 1.503277593E-10 | proton mass energy equivalent [J] uncertainty=0.000 000 018 e-10
proton_mass_energy_equivalent_in_MeV | 938.2720813 | proton mass energy equivalent in MeV [MeV] uncertainty=0.000 0058
proton_mass_in_u | 1.007276466879 | proton mass in u [u] uncertainty=0.000 000 000 091
proton_molar_mass | 0.001007276466879 | proton molar mass [kg mol^{-1}] uncertainty=0.000 000 000 091 e-3
proton_muon_mass_ratio | 8.88024338 | proton-muon mass ratio [] uncertainty=0.000 000 20
proton_neutron_mag_mom_ratio | -1.45989805 | proton-neutron mag. mom. ratio [] uncertainty=0.000 000 34
proton_neutron_mass_ratio | 0.99862347844 | proton-neutron mass ratio [] uncertainty=0.000 000 000 51
proton_rms_charge_radius | 8.751E-16 | proton rms charge radius [m] uncertainty=0.0061 e-15
proton_tau_mass_ratio | 0.528063 | proton-tau mass ratio [] uncertainty=0.000 048
quantum_of_circulation | 0.00036369475486 | quantum of circulation [m^2 s^{-1}] uncertainty=0.000 000 0017 e-4
quantum_of_circulation_times_2 | 0.00072738950972 | quantum of circulation times 2 [m^2 s^{-1}] uncertainty=0.000 000 0033 e-4
Rydberg_constant | 10973731.568508 | Rydberg constant [m^{-1}] uncertainty=0.000 065
Rydberg_constant_times_c_in_Hz | 3.289841960355E+15 | Rydberg constant times c in Hz [Hz] uncertainty=0.000 000 000 019 e15
Rydberg_constant_times_hc_in_eV | 13.605693009 | Rydberg constant times hc in eV [eV] uncertainty=0.000 000 084
Rydberg_constant_times_hc_in_J | 2.179872325E-18 | Rydberg constant times hc in J [J] uncertainty=0.000 000 027 e-18
Sackur_Tetrode_constant_1_K_100_kPa | -1.1517084 | Sackur-Tetrode constant (1 K, 100 kPa) [] uncertainty=0.000 0014
Sackur_Tetrode_constant_1_K_101325_kPa | -1.1648714 | Sackur-Tetrode constant (1 K, 101.325 kPa) [] uncertainty=0.000 0014
second_radiation_constant | 0.0143877736 | second radiation constant [m K] uncertainty=0.000 000 83 e-2
shielded_helion_gyromag_ratio | 203789458.5 | shielded helion gyromag. ratio [s^{-1} T^{-1}] uncertainty=0.000 000 027 e8
shielded_helion_gyromag_ratio_over_2_pi | 32.43409966 | shielded helion gyromag. ratio over 2 pi [MHz T^{-1}] uncertainty=0.000 000 43
shielded_helion_mag_mom | -1.074553080E-26 | shielded helion mag. mom. [J T^{-1}] uncertainty=0.000 000 014 e-26
shielded_helion_mag_mom_to_Bohr_magneton_ratio | -0.001158671471 | shielded helion mag. mom. to Bohr magneton ratio [] uncertainty=0.000 000 014 e-3
shielded_helion_mag_mom_to_nuclear_magneton_ratio | -2.127497720 | shielded helion mag. mom. to nuclear magneton ratio [] uncertainty=0.000 000 025
shielded_helion_to_proton_mag_mom_ratio | -0.7617665603 | shielded helion to proton mag. mom. ratio [] uncertainty=0.000 000 0092
shielded_helion_to_shielded_proton_mag_mom_ratio | -0.7617861313 | shielded helion to shielded proton mag. mom. ratio [] uncertainty=0.000 000 0033
shielded_proton_gyromag_ratio | 267515317.1 | shielded proton gyromag. ratio [s^{-1} T^{-1}] uncertainty=0.000 000 033 e8
shielded_proton_gyromag_ratio_over_2_pi | 42.57638507 | shielded proton gyromag. ratio over 2 pi [MHz T^{-1}] uncertainty=0.000 000 53
shielded_proton_mag_mom | 1.410570547E-26 | shielded proton mag. mom. [J T^{-1}] uncertainty=0.000 000 018 e-26
shielded_proton_mag_mom_to_Bohr_magneton_ratio | 0.001520993128 | shielded proton mag. mom. to Bohr magneton ratio [] uncertainty=0.000 000 017 e-3
shielded_proton_mag_mom_to_nuclear_magneton_ratio | 2.792775600 | shielded proton mag. mom. to nuclear magneton ratio [] uncertainty=0.000 000 030
speed_of_light_in_vacuum | 299792458 | speed of light in vacuum [m s^{-1}] uncertainty=(exact)
standard_acceleration_of_gravity | 9.80665 | standard acceleration of gravity [m s^{-2}] uncertainty=(exact)
standard_atmosphere | 101325 | standard atmosphere [Pa] uncertainty=(exact)
standard_state_pressure | 100000 | standard-state pressure [Pa] uncertainty=(exact)
Stefan_Boltzmann_constant | 5.670367E-8 | Stefan-Boltzmann constant [W m^{-2} K^{-4}] uncertainty=0.000 013 e-8
tau_Compton_wavelength | 6.97787E-16 | tau Compton wavelength [m] uncertainty=0.000 063 e-15
tau_Compton_wavelength_over_2_pi | 1.11056E-16 | tau Compton wavelength over 2 pi [m] uncertainty=0.000 010 e-15
tau_electron_mass_ratio | 3477.15 | tau-electron mass ratio [] uncertainty=0.31
tau_mass | 3.16747E-27 | tau mass [kg] uncertainty=0.000 29 e-27
tau_mass_energy_equivalent | 2.84678E-10 | tau mass energy equivalent [J] uncertainty=0.000 26 e-10
tau_mass_energy_equivalent_in_MeV | 1776.82 | tau mass energy equivalent in MeV [MeV] uncertainty=0.16
tau_mass_in_u | 1.90749 | tau mass in u [u] uncertainty=0.000 17
tau_molar_mass | 0.00190749 | tau molar mass [kg mol^{-1}] uncertainty=0.000 17 e-3
tau_muon_mass_ratio | 16.8167 | tau-muon mass ratio [] uncertainty=0.0015
tau_neutron_mass_ratio | 1.89111 | tau-neutron mass ratio [] uncertainty=0.000 17
tau_proton_mass_ratio | 1.89372 | tau-proton mass ratio [] uncertainty=0.000 17
Thomson_cross_section | 6.6524587158E-29 | Thomson cross section [m^2] uncertainty=0.000 000 000 91 e-28
triton_electron_mass_ratio | 5496.92153588 | triton-electron mass ratio [] uncertainty=0.000 000 26
triton_g_factor | 5.957924920 | triton g factor [] uncertainty=0.000 000 028
triton_mag_mom | 1.504609503E-26 | triton mag. mom. [J T^{-1}] uncertainty=0.000 000 012 e-26
triton_mag_mom_to_Bohr_magneton_ratio | 0.0016223936616 | triton mag. mom. to Bohr magneton ratio [] uncertainty=0.000 000 0076 e-3
triton_mag_mom_to_nuclear_magneton_ratio | 2.978962460 | triton mag. mom. to nuclear magneton ratio [] uncertainty=0.000 000 014
triton_mass | 5.007356665E-27 | triton mass [kg] uncertainty=0.000 000 062 e-27
triton_mass_energy_equivalent | 4.500387735E-10 | triton mass energy equivalent [J] uncertainty=0.000 000 055 e-10
triton_mass_energy_equivalent_in_MeV | 2808.921112 | triton mass energy equivalent in MeV [MeV] uncertainty=0.000 017
triton_mass_in_u | 3.01550071632 | triton mass in u [u] uncertainty=0.000 000 000 11
triton_molar_mass | 0.00301550071632 | triton molar mass [kg mol^{-1}] uncertainty=0.000 000 000 11 e-3
triton_proton_mass_ratio | 2.99371703348 | triton-proton mass ratio [] uncertainty=0.000 000 000 22
unified_atomic_mass_unit | 1.660539040E-27 | unified atomic mass unit [kg] uncertainty=0.000 000 020 e-27
von_Klitzing_constant | 25812.8074555 | von Klitzing constant [ohm] uncertainty=0.000 0059
weak_mixing_angle | 0.2223 | weak mixing angle [] uncertainty=0.0021
Wien_frequency_displacement_law_constant | 5.8789238E+10 | Wien frequency displacement law constant [Hz K^{-1}] uncertainty=0.000 0034 e10
Wien_wavelength_displacement_law_constant | 0.0028977729 | Wien wavelength displacement law constant [m K] uncertainty=0.000 0017 e-3
calorie_joule_relationship | 4.184 | calorie-joule relationship [J] uncertainty=(exact)
h | 6.626070040E-34 | h [J] The Planck constant (Js)
c | 299792458 | c [Hz] Speed of light (ms$^{-1}$)
kb | 1.38064852E-23 | kb [J] The Boltzmann constant (JK$^{-1}$)
R | 8.3144598 | R [J mol^-1 K^-1] Universal gas constant (JK$^{-1}$mol$^{-1}$)
bohr2angstroms | 0.52917721067 | bohr2angstroms [AA] Bohr to Angstroms conversion factor
bohr2m | 5.2917721067E-11 | bohr2m [m] Bohr to meters conversion factor
bohr2cm | 5.291772106700E-9 | bohr2cm [cm] Bohr to centimeters conversion factor
amu2g | 1.660539040000E-24 | amu2g [g] Atomic mass units to grams conversion factor
amu2kg | 1.660539040E-27 | amu2kg [kg] Atomic mass units to kg conversion factor
au2amu | 0.000548579909070 | au2amu [u] Atomic units (m$@@e$) to atomic mass units conversion factor
hartree2J | 4.359744650E-18 | hartree2J [J] Hartree to joule conversion factor
hartree2aJ | 4.359744650 | hartree2aJ [aJ] Hartree to attojoule (10$^{-18}$J) conversion factor
cal2J | 4.184 | cal2J [J] Calorie to joule conversion factor
dipmom_au2si | 8.478353552E-30 | dipmom_au2si [C m] Atomic units to SI units (Cm) conversion factor for dipoles
dipmom_au2debye | 2.541746451895025916414946904 | dipmom_au2debye [???] Atomic units to Debye conversion factor for dipoles
dipmom_debye2si | 3.335640951E-30 | dipmom_debye2si [???] Debye to SI units (Cm) conversion factor for dipoles
c_au | 137.035999139 | c_au [] Speed of light in atomic units
hartree2ev | 27.21138602 | hartree2ev [eV] Hartree to eV conversion factor
hartree2wavenumbers | 219474.6313702 | hartree2wavenumbers [cm^-1] Hartree to cm$^{-1}$ conversion factor
hartree2kcalmol | 627.5094737775374055927342256 | hartree2kcalmol [kcal mol^-1] Hartree to kcal mol$^{-1}$ conversion factor
hartree2kJmol | 2625.4996382852165050 | hartree2kJmol [kJ mol^-1] Hartree to kilojoule mol$^{-1}$ conversion factor
hartree2MHz | 6579683920.711 | hartree2MHz [MHz] Hartree to MHz conversion factor
kcalmol2wavenumbers | 349.7550882318031839256652313 | kcalmol2wavenumbers [kcal cm mol^-1] kcal mol$^{-1}$ to cm$^{-1}$ conversion factor
e0 | 8.854187817E-12 | e0 [F m^-1] Vacuum permittivity (Fm$^{-1}$)
na | 6.022140857E+23 | na [mol^-1] Avogadro’s number
me | 9.10938356E-31 | me [kg] Electron rest mass (in kg)