Table shows the comparison of the direct method, the FEM, and the six variants of ECI for the triplet and singlet states of MgG 2+ 4 . As said previously, in FEM and ECI+FDA calculations for this system the APC of Mg 2+ was not set to zero but to +2. The corresponding energies and oscillator strengths for the "real" FDA (with APC of Mg 2+ also set to zero) calculations are given in Table . The ECI vectors of the full-system singlet states are given in Tables S11-S17.