<div>Here, <span data-equation="g_q" class="ltx_Math" contenteditable="false">\(g_q\)</span> represents the electron-phonon coupling strength, <span data-equation="U_q" class="ltx_Math" contenteditable="false">\(U_q\)</span> is the Coulomb interaction, and <span data-equation="V_q" class="ltx_Math" contenteditable="false">\(V_q\)</span> 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 <span data-equation="k_F" class="ltx_Math" contenteditable="false">\(k_F\)</span> also changes the electron density of states around it:<br></div>