To model photoexcitation, we utilize a FD model that is extended to include the electronic ground state. We denote the ground state as |G⟩ and the three exciton basis states as we have previously, i.e., |L⟩, |+⟩, and |-⟩. Following the model described in Ref. 34, we write the wavefunction for the 4-state exciton system as,