How do I calculate the 10Dq and Racah parameters of complexes with intermediate spin and how do I know which transition states are present? For example, the octahedral complex of Fe(II) triplet, only the Tanabe-Sugano diagram predicts that the ground state is a quintet 5T2 for weak-field ligands and a singlet 1A1 for strong-field ligands. I performed theoretical calculations using TDDFT.