AsymptoticPoissonProblem(R, k, u, v, R̃[; w′=similar(U)])

Create the Poisson problem of order k for the mutual density u†(r) .* v(r); the Poisson problem is solved numerically within the domain of R̃ and an asymptotic solution is used outside. For this to be valid, u or v have to vanish before the end of R̃. w′ is a MulQuasiVector of the same kind as u and v, and may optionally be provided as a pre-allocated vector, in case it is e.g. the diagonal of a potential matrix.

PoissonProblem(R, k[, ::Type{C}=eltype(R); poisson_cache])

Create the Poisson problem of order k for densities expanded over R.

get_double_laplacian(R, k)

Return Laplacian (multiplied by 2) for partial wave k of the basis R, -∂ᵣ² + k(k+1)/r².