We observe a linear dependence of the NEVPT2-DMET VEE on the inverse of the number of embedding orbitals. This motivated us to perform a linear extrapolation to achieve the non-embedding limit. For a supercell as small as N C 62 , it is possible to perform a full nonembedding calculation, while for larger supercells this is not affordable, and this is why an embedding technique is needed in the first place. Therefore, such a linear extrapolation is necessary to achieve the non-embedding limit of the NEVPT2-DMET excitation energy.