to be the best choice for such localized systems, namely uniform selection for the first particle and fully-weighted selection for the second particle and the two holes. Notably this sampling scheme is neither the one suggested by Holmes et al. nor the one we have been using in NECI. The second system is Full CI on the N 2 dimer at equilibrium distance with a Dunning's cc-pVQZ basis 36 using Hartree-Fock orbitals, resulting in a (14,110) active space. This is a single-reference system with highly delocalized orbitals that fulfill the Brillouin theorem, which makes the double excitations particularly important.