Struct MultipoleExpansion 

pub struct MultipoleExpansion {
    pub l_max: usize,
    pub dx: [f64; 3],
    pub shape: [usize; 3],
}

Multipole expansion calculator for computing far-field boundary conditions.

Fields

l_max: usize

Maximum angular momentum quantum number.

dx: [f64; 3]

Grid spacing.

shape: [usize; 3]

Grid shape.

Implementations

impl MultipoleExpansion

pub fn new(shape: [usize; 3], dx: [f64; 3], l_max: usize) -> Self

Create a multipole expansion calculator for the given grid geometry.

pub fn compute_moments( &self, density: &DensityField, g: f64, ) -> Vec<(usize, i32, f64)>

Compute multipole moments q_lm from the density field.

q_lm = integral rho(x) * r^l * Y_lm(theta, phi) * dx^3

Returns moments indexed as [(l, m)] for l=0..l_max, m=-l..l.

pub fn evaluate_potential( &self, moments: &[(usize, i32, f64)], x: f64, y: f64, z: f64, g: f64, ) -> f64

Evaluate the multipole potential at a point (x, y, z).

pub fn compute_boundary_values( &self, density: &DensityField, g: f64, ) -> BoundaryValues

Compute boundary values from multipole expansion.