In this system, CVCs emerge under excitation with circularly polarized light. Under this excitation condition, the basis states |x⟩ and |y⟩ are not independently excitable. Rather, circularly polarized photons excite complex superpositions of the |x⟩ and |y⟩ states. This has been demonstrated for Mg-porphyrin (possessing D 4h symmetry). The appropriate basis states for describing these superpositions are the eigenstates of the angular momentum operator, |+⟩ and |-⟩, defined as, To model excitons generated from circularly polarized light, we thus perform a change of basis from the states (|L⟩, |x⟩, |y⟩) to (|L⟩, |+⟩, |-⟩). The resulting FD Hamiltonian is,