Optical transitions for bulk F 0 center have been studied utilizing the periodic-DMET algorithm with complete active space self-consistent field (CASSCF) and second-order Nelectron valence state perturbation theory (NEVPT2) high-level impurity solvers. For a more thorough understanding of the DMET framework, we refer the readers to the available extensive literature. Briefly, the algorithm begins with a Slater determinant trial wave function that approximates the entire system. It can be a restricted closed-shell Hartree Fock (RHF) or restricted open-shell Hartree Fock (ROHF) wave function. Subsequently, all orbitals (N tot in number) are transformed into maximally localized Wannier functions (MLWFs) and divided into N frag number of fragment and the remainder environment MLWFs, based on the specific system being investigated. By performing a singular value decomposition (Schmidt decomposition) on the fragment-environment block of the full one-body reduced density matrix, a set of bath orbitals is generated as a linear combination of environment MLWFs that are entangled with the fragment MLWFs. By using a RHF (ROHF) Slater determinant trial wave function, there will be a maximum of N frag (N frag +2S) bath orbitals, where S represents the total spin quantum number of the periodic supercell. To solve the DMET embedding Hamiltonian, multiconfigurational methods such as CASSCF and NEVPT2 are employed.