Intuitively, the generalized Tavis-Cummings (GTC) Hamiltonian is to the generalized dipole gauge Hamiltonian as the Jaynes-Cummings Hamiltonian is to the traditional dipole gauge Hamiltonian. In this manner, there are a series of approximations from Eq. 74 to obtain the GTC Hamiltonian. Namely, we first truncate each molecule to the two-level approximation and remove permanent dipole, such that the dipole operator for a given molecule can be written as μA = µ eg A σx , where µ eg A is the transition dipole moment between the ground and excited states for the molecule A. Then, the dipole selfenergy terms (last line of Eq. 74) are entirely neglected. Finally, the rotating wave approximation is performed such that for the interaction terms become: