Quantum phase transitions in one-dimensional half-filled ionic Peierls–Hubbard model

Liu Shuan Yang, Wenling Chan, Shi-Jian Gu +1 more

Anh-Tuan Hoang, Thi-Hai-Yen Nguyen, Duc‐Anh Le

Yu‐Zhong Zhang, Chao Wu, Hua Lin

Density matrix renormalization group methods are used to investigate the quantum phase diagram of a one-dimensional half-filled ionic Peierls-Hubbard model at the antiadiabatic limit where quantum phonon fluctuations are taken into account partially. We found that two continuous phase transitions always exist from dimerized spin-gapped (bond-order-wave) state to band-insulator and undimerized spin-gapless (Mott-insulator) phase while undimerized spin-gapless phase vanishes at the adiabatic limit. Our results indicate that quantum phonon fluctuations, electron-electron interaction, and ionic potential combine in the formation of the bond-order wave phase.

Ji-Woo Lee, Sung Moon Kim, Kyo Yeon Cho

Pinaki Sengupta, Anders W. Sandvik, David K Campbell

We report quantum Monte Carlo (stochastic series expansion) results for the transition from a Mott insulator to a dimerized Peierls insulating state in a half-filled, one-dimensional extended Hubbard model coupled to optical bond phonons. Using electron-electron (e-e) interaction parameters corresponding approximately to polyacetylene, we show that the Mott-Peierls transition occurs at a finite value of the electron-phonon (e-ph) coupling. We discuss several different criteria for detecting the transition and show that they give consistent results. We calculate the critical e-ph coupling as a function of the bare phonon frequency and also investigate the sensitivity of the critical coupling to the strength of the e-e interaction. In the limit of strong e-e couplings, we map the model to a spin-Peierls chain and compare the phase boundary with previous results for the spin-Peierls transition. We point out effects of a nonlinear spin-phonon coupling neglected in the mapping to the spin-Peierls model.

Soo Hyun Cho, Ji-Woo Lee