For the purposes of modeling electron transfer with Marcus theory, it can be very helpful to work with a set of diabatic states. Luckily, for a CASSCF(2,2) calculation, generating such diabatic states is often straightforward. Here, we will generate an adiabatic-to-diabatic transformation by diagonalizing the impurity projector ŵ in the basis of the three DW-SA-cCASSCF(2,2) states (S 0 , S 1 and S 2 ). For the one-impurity Hamiltonian in Eq. 34, we diagonalize ŵ = d † d: