A periodic equation-of-motion coupled-cluster implementation applied to $F$-centers in alkaline earth oxides.

We present an implementation of equation of motion coupled-cluster singles and doubles (EOM-CCSD) theory using periodic boundary conditions and a plane wave basis set. Our implementation of EOM-CCSD theory is applied to study $F$-centers in alkaline earth oxides employing a periodic supercell approach. The convergence of calculated electronic excitation energies for neutral color centers in MgO, CaO and SrO crystals with respect to orbital basis set and system size is explored. We discuss extrapolation techniques that approximate excitation energies in the complete basis set limit and reduce finite size errors. Our findings demonstrate that EOM-CCSD theory can predict optical absorption energies of $F$-centers in good agreement with experiment. Furthermore, we discuss calculated emission energies corresponding to the decay from triplet to singlet states, responsible for the photoluminescence properties. Our findings are compared to experimental and theoretical results available in literature.