Active Space Wavefunction Methods for Defects in Solids

Quantum embedding theories offer a means to combine multiple levels of electronic structure theory in order to predict accurate electronic properties of correlated materials. These methods can correct errors in low-level theories, such as the delocalization error in density functional theory or the lack of electron correlation in Hartree-Fock theory. In this work, we develop a purely wavefunction based approach to quantum embedding in order to compute correlated electronic states of systems with weak to strong correlations within spatially localized embedded fragments. Furthermore, we benchmark various active space wavefunction methods (CASSCF, CCSD, etc.) for quantum defects in solids.