Concerning the integration in case of first-principles electronic structure calculation, tetrahedron method is famous for the k-space integration. Is there any method for the efficient integration in real space? Is it common to convert the integral variable and fucntions to k-space before executing the integral? Can one use the integration libraries such as "quad" in the case of real space? I read an article where the author Fourier transforms the pseudo-wave function (Wannier function?)

Thanks in advance for your kind reply.