Our integral is now given by $$ I=\int_0^{\infty} r_1^2dr_1 \int_0^{\infty}r_2^2dr_2 \int_0^{\pi}dcos(\theta_1)\int_0^{\pi}dcos(\theta_2)\int_0^{2\pi}d\phi_1\int_0^{2\pi}d\phi_2 \frac{\exp{-2\alpha (r_1+r_2)}}{r_{12}} $$ For the angles we need to perform the integrations over \( \theta_i\in [0,\pi] \) and \( \phi_i \in [0,2\pi] \). However, for the radial part we can now either use

• Gauss-Legendre wth an appropriate mapping or
• Gauss-Laguerre taking properly care of the integrands involving the \( r_i^2 \exp{-(2\alpha r_i)} \) terms.