Dominant particle-hole contributions to the phonon dynamics in the spinless one-dimensional Holstein modelS. Sykora1, A. Hübsch2 and K. W. Becker1
1 Institut für Theoretische Physik, Technische Universität Dresden 01062 Dresden, Germany
2 Max-Planck-Institut für Physik komplexer Systeme - Nöthnitzer Straße 38 01187 Dresden, Germany
received 26 May 2006; accepted in final form 27 September 2006
published online 18 October 2006
In the spinless Holstein model at half-filling the coupling of electrons to phonons is responsible for a phase transition from a metallic state at small coupling to a Peierls distorted insulated state when the electron-phonon coupling exceeds a critical value. For the adiabatic case of small phonon frequencies, the transition is accompanied by a phonon softening at the Brillouin-zone boundary whereas a hardening of the phonon mode occurs in the anti-adiabatic case. The phonon dynamics studied in this letter do not only reveal the expected renormalization of the phonon modes but also show remarkable additional contributions due to electronic particle-hole excitations.
71.10.Fd - Lattice fermion models (Hubbard model, etc.).
71.30.+h - Metal-insulator transitions and other electronic transitions.
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