Physical Constants

ALPHA

The fine-structure constant $\alpha \approx 1/137$ (dimensionless), which characterizes the strength of electromagnetic interactions.

This value is defined using exactly the recommended value given in [1], but can be safely converted to any floating-point type (e.g., Float64(ALPHA) or one(Float32)*ALPHA) in a type-stable and compile-time safe manner.

ALPHA_SQUARE

The square of the fine-structure constant, i.e. $\alpha^2$. Useful in second-order electromagnetic processes.

Supports type-stable conversion to all standard floating-point types.

ELEMENTARY_CHARGE

The elementary charge $e$ in natural units, defined as $\sqrt{4\pi \alpha}$.

Dimensionless in natural units; useful in calculating Coulomb interactions or electromagnetic coupling factors.

This value is defined using exactly the recommended value given in [1], but can be safely converted to any floating-point type (e.g., Float64(ELEMENTARY_CHARGE) or one(Float32)*ELEMENTARY_CHARGE) in a type-stable and compile-time safe manner.

ELEMENTARY_CHARGE_SQUARE

The square of the elementary charge in natural units: $e^2$.

Commonly appears as a prefactor in scattering cross sections and Coulomb potentials.

ELECTRONMASS

Electron rest mass in electronvolts (eV), consistent with natural units.

This value is defined using exactly the recommended value given in [1], but can be safely converted to any floating-point type (e.g., Float64(ELECTRONMASS) or one(Float32)*ELECTRONMASS) in a type-stable and compile-time safe manner.

ONE_OVER_FOURPI

The value $1 / (4\pi)$, often used as a Coulomb prefactor in Gaussian or natural unit systems.

Convertible at compile time to all standard float types.