Unlike QDET, we use restricted open-shell Hartree-Fock (ROHF) as the lower level theory, which makes the method free from the "double counting" problem. We use CASSCF as the high-level impurity solver to appropriately address the strongly correlated defect region, followed by n-electron valence state second-order perturbation theory (NEVPT2), to account for the portion of dynamic correlation which is missing at the CASSCF level. The rest of the system (environment) is approximately described with a "bath" constructed from a Schmidt decomposition of the full-system HF wave function. Recently, it has been shown that pDMET offers an accurate and affordable ab initio approach for studying the electronic structure of neutral point defects. However, pDMET has not yet been investigated for charged defects. In this work, we focus on the well tested NV -center in diamond to explore the performance of pDMET for charged electronic excitations localized within the defect site.