Hence, unlike in G 4 , going to ECISD+ESP in MgG leads to additional improvements. The RMSD value of the energies further drop by 20-40%, to 0.08 eV for triplets and 0.22 eV for singlets. As visible from the degeneracy pattern and oscillator strengths, ECISD+ESP describes the S 5 -S 8 states slightly more accurately than ECIS+ESP, as the dark, totally symmetric state (Table ) is lowered in energy (becoming the S 7 ), and the S 8 showing the correct oscillator strength (compared to the reference).