RT Journal Article T1 Phonon softening and dispersion in the 1D Holstein model of spinless fermions A1 Creffield, Charles A1 Sangiovanni, G. A1 Capone, M. AB We investigate the effect of electron-phonon interaction on the phononic properties in the onedimensional half-filled Holstein model of spinless fermions. By means of determinantal Quantum Monte Carlo simulation we show that the behavior of the phonon dynamics gives a clear signal of the transition to a charge-ordered phase, and the phase diagram obtained in this way is in excellent agreement with previous DMRG results. By analyzing the phonon propagator we extract the renormalized phonon frequency, and study how it first softens as the transition is approached and then subsequently hardens in the charge-ordered phase. We then show how anharmonic features develop in the phonon propagator, and how the interaction induces a sizable dispersion of the dressed phonon in the non-adiabatic regime. PB Springer SN 1434-6028 YR 2005 FD 2005-03 LK https://hdl.handle.net/20.500.14352/51585 UL https://hdl.handle.net/20.500.14352/51585 LA eng NO © Springer.We thank C. Castellani and S. Ciuchi for valuable discussions. We also acknowledge Italian MIUR Cofin2003 for financial support. NO MIUR. Italy DS Docta Complutense RD 9 abr 2025