We briefly review the formalism of nonadiabatic couplings in both CIS and LR-TDDFT in order to demonstrate the origin of the topology problem for CXs that involve the reference state. For LR-TDDFT, we use a "pseudo-wave function" formalism in which one treats the Kohn-Sham determinant as a wave function and derivative couplings are obtained from analytic gradient theory, in analogy to the way in which nonadiabatic couplings are derived for the CIS method. This approach sidesteps certain divergences associated with the use of quadratic response theory to obtain derivative couplings. In CIS, the electronic wavefunction is expressed as a linear combination of singly-excited Slater determinants |Φ ia , as in Eq. (1). The coefficients c 0 and {c ia } in Eq. (1) are determined by solving the Schrödinger equation Ĥ|Ψ = E|Ψ after projecting the Hamiltonian onto the single excitation space: