From now on we will drop the subscript \( l \) in all equations. In order to solve the Lippman-Schwinger equation in momentum space, we need first to write a function which sets up the mesh points. We need to do that since we are going to approximate an integral through $$ \int_a^bf(x)dx\approx\sum_{i=1}^Nw_if(x_i), $$ where we have fixed \( N \) lattice points through the corresponding weights \( w_i \) and points \( x_i \). Typically obtained via methods like Gaussian quadrature.