Where F is the unmodified Fock matrix obtained from the initial calculation on the entire system and S is the overlap matrix in the atomic orbital basis. In the present case, SS-FNO-IP-EOM-CCSD* calculation is performed on the active system embedded in the Hartree-Fock wave function of the surrounding atoms. The partitioning is performed through a combination of Pipek-Mezey (PM) localization and Mulliken population screening following the work of Waldrop et. al. 69 All the embedding-based SS-FNO-IP-EOM-CCSD* calculations were performed by interfacing BAGH with the PythonProjectorEmbedding 70 code of Waldrop et. al. Unlike ref , the Mulliken population based truncation of the atomic orbital space is not performed in the present study as the use of frozen natural orbital will truncate the redundant virtual orbitals.