Physical review. B, Condensed matter
Gapped and gapless ground state of the one-dimensional spinless Holstein model
Hongxing Zheng, M. Avignon
Abstract
An analytical approach has been developed to study the ground-state phase diagram of a one-dimensional spinless Holstein model and its gapped and gapless phases. We show that when the electron-phonon coupling constant ${g}^{2}/{\ensuremath{\omega}}_{0}$ decreases or the phonon frequency ${\ensuremath{\omega}}_{0}$ increases the lattice dimerization and the gap in the fermionic spectrum decreases gradually. At some critical value ${(g}^{2}/{\ensuremath{\omega}}_{0}{)}_{c}$ or ${\ensuremath{\omega}}_{0c},$ the lattice dimerization disappears and the system becomes gapless Luttinger liquid with phonon-renormalized velocity $v(q)$ and stiffness constant $K(q).$ Our numerical results agree quite well with the results of Monte Carlo simulations.