Function coulomb_wave_functions 

pub fn coulomb_wave_functions(
    l: u32,
    eta: f64,
    rho: f64,
) -> Option<(f64, f64, f64, f64)>

Coulomb wave functions (F_L, G_L, F’_L, G’_L) via Steed’s CF1+CF2 method.

Implements Barnett’s Coulfg algorithm (CPC 21, 1981, 297–314) as adapted in SAMMY coulomb/mrml08.f90. Returns None if ρ ≤ 0 or the continued fractions fail to converge (nuclear-physics ρ values always converge).

The returned derivatives are with respect to ρ.

SAMMY Reference

coulomb/mrml08.f90 Coulfg subroutine.

Arguments

• l — Orbital angular momentum quantum number L.
• eta — Sommerfeld parameter η (0 for neutral particles).
• rho — Dimensionless channel parameter ρ = k·a (must be > 0).

Returns

Some((F_L, G_L, F'_L, G'_L)) on success, None if ρ is too small or the continued fractions diverge.