Overall errors of excitation energies and SOMEs with respect to the reference TDA and DFT/MRCI results are summarized in Table . Corresponding correlation plots for excitation energies and spin-orbit coupling matrix elements are given in Figures and. In sum, total RMSDs with respect to the reference TDA@PBE0 results are of minor 0.10 eV for excitation energies and of 3.7 cm -1 for spin-orbit coupling elements. Deviations with respect to DFT/MRCI references amount up to total RMSDs of 0.28 eV for excitation energies and 5.9 cm -1 for spin-orbit coupling elements. Due to the neglect of spin-other-orbit interactions in the Hamiltonian and differences in basis sets and setup, relying on the Gaussian and augmented plane wave implementation with all-electron potentials in comparison to all-electron implementations for both reference data sets, the TDA@PBE0 results of this work are considered less accurate by construction in comparison to the TDA reference. The nevertheless good agreement with the methodologically most accurate DFT/MRCI results must therefore rely on fortuitious error cancellation. In case of the SOME, two points clearly deviate from Fig. (right) at 137.2 cm -1 and 83.6 cm -1 . These belong to 1 3 A 2 |H SO z |1 1 A 1 and 1 3 B 2 |H SO x |2 1 A 1 from thioformaldehyde. For 1 3 A 2 |H SO z |1 1 A 1 , the deviation between MRDFT and the reference TDA-TDDFT calculation is with 37.1 cm -1 much larger than our calculation with only 8.4 cm -1 . This could be due to a compensation of errors between the fully Gaussian basis set used in turbomole and the Gaussian and augmented plane waves approach used in CP2K. For 1 3