Development of Relativistic Equation-of-Motion Coupled-Cluster Methods

The presentation focuses on the development of two variants of relativistic equation-of-motion coupled-cluster (EOM-CC) methods with spin-orbit coupling (SOC) included at the orbital level. We present an efficient implementation for relativistic core-valence separation EOM-CC singles and doubles (CVS-EOM-CCSD) method. Our benchmark study on L_2,3-edge x-ray absorption near edge spectra (XANES) of Ar, Kr and Xe demonstrates its accuracy and applicability. The calculations show rather small intrinsic errors of CVS-EOM-CC even for deep core-excited states of heavy elements. We also present an implementation of relativistic EOM double electron affinity (EOMDEA) CCSD method for treating heavy-atomcontaining molecules with two open-shell electrons. EOMDEA-CCSD can treat low-lying electronic states on the same footing, therefore avoiding possible biases associated with active space selection. We also carefully discuss the dependence of the computed results on the choice of orbitals.