1598 electrons in a cubic supercell, at a density corresponding to the Wigner-Seitz radius of 1 atomic unit. The calculations are performed with a finite plane-wave basis, as detailed in Ref. [20]. For comparison we also include data for the 'mosaic' coupled cluster doubles method (mCCD) and RPA with screened second-order exchange (RPA+SOSEX) from that reference. RPA+SOSEX represents a canonical example of a convergent theory in this context. While the per electron correlation energy continues to increase with the size of the supercell for MP2, RPA+SOSEX quickly approaches a nearly constant value. For our purposes, the mCCD method is also an interesting benchmark. Here, the amplitude equations of CCD are reduced to the pure driver term (also present in MP2) and the 'mosaic' diagrams, which can be interpreted as a renormalization of the single particle Hamiltonian. From this perspective, mCCD thus resembles an ab initio analogue to the regularized MP2 methods studied herein. It can be seen that mCCD also deviates strongly from MP2 for larger supercells, indicating an apparent convergence (or at least slower divergence).