and is therefore affected by two aspects: (i) summing over fewer occupied states in the DFT-embedded GW -BSE calculation and (ii) the changes in the molecular orbitals themselves. While Σ x itself only depends on the occupied orbitals, it is important to realize that it enters the calculation of quasiparticle energies also of unoccupied states. Performing a similar analysis for the frequency-dependent correlation part is more complicated. Recall first that Eq. ( ) gave