In this work, we employed the KRR method to train the analytical expression of dipoles (permanent and transition dipoles) for the azomethane molecule. All of the training data are generated at the SA-2-CAS(6,4) level of theory, with the 6-31G* basis set. This ensures the dipole and its derivative of it are also at the level of CASSCF, which will be consistent with the other nuclear gradient (see Eq. 34) used in the dynamics simulations. Below, we briefly describe our training procedure.