3. Energy convergence of the ground state (GS, in blue) and excited state (ES, in red) of CN3 with respect to the number of determinants N det in the reference space. e zeroth-order energy E (0) (do ed) , its second-order corrected value E (0) + E (dashed) as well as its renormalized version E (0) + ZE (solid) are represented. See Table for raw data.