In my project, there are some spin forbidden organometallic reactions that involves both the triplet minima and singlet transition state (TS). Using the penalty method in qchem as well the method of Harvey, two candidate structures of the minimum energy crossing point (MECP) were identified. However, these two structures, while similar in energy, do not agree with each other in geometry.
Since these structures are not stationary points, IRC is not applicable to check whether one or both of these structures connect to the aforementioned TS and mins. Are there any known systematic methods in DFT (because CASSCF is impractical for molecules this big) to check connectivity of a MECP to specific TS and mins besides the more brute force method of checking vibrational mode surfaces and look for degeneracy when scanning along them?