For each DMET calculation, the number of fragment orbitals (N frag ) is selected from the MLWFs located within a specified distance, r frag , from the initial OV-Mg 6 fragment. The corresponding N frag +2 entangled bath orbitals are included to obtain the N emb . Following this procedure, DMET excitation energies are calculated for different values of N frag , by gradually increasing r frag . This strategy is applied to each of the four supercells. In principle, N frag can be increased only up to (N tot -2)/2 in case of a ROHF bath. Here N tot is the total number of atomic orbitals or total number of MLWFs for a particular supercell. However, the location of the DMET fragment itself in the computational supercell is also crucial to dictate the maximum N frag (or r frag ) that will be physically meaningful. The distance r frag should not exceed the distance of the fragment atoms from the atoms on the supercell boundary to avoid spurious interactions with periodic images, which can lead to specious trends in DMET VEEs. Additionally, the case where N tot /N emb =1, is the non-embedding limit VEEs calculated through DMET.