Here, \(g_q\) represents the electron-phonon coupling strength, \(U_q\) is the Coulomb interaction, and \(V_q\) is the electron-electron screening potential. By using this criterion, it is possible to extract a well-defined phase-change temperature for when the CDW state emerges. CDW states are usually accompanied by a full or partial gap opening. In the case of the 1D Frohlich Hamiltonian, we can see that the band gap that forms around \(k_F\) also changes the electron density of states around it: