Here we consider only such perturbative scheme in which SOCs are computed as ma-trix elements of the BP Hamiltonian using non-relativistic wave functions . Different implementations of full and approximate SOC treatments have been reported for different types of wave functions including those obtained by complete activespace self-consistent field (CASSCF) , restricted active space self-consistent field (RASSCF) , multi-reference configuration interaction (MRCI) , coupled-cluster (CC) response , equation-of-motion CC (EOM-CC) , and multi-reference CC (MRCC) within the Mk-MRCCSD formulation . DFT implementations have also been reported .