The two-dimensional optical Su-Schrieffer-Heeger model: ground state and thermodynamic properties

Fuente: arXiv
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Autores principales: Silva, Jadson L. Portela e, Rein, Gabriel, Sousa-Júnior, Sebastião dos A., Assaad, Fakher F., Costa, Natanael C.
Formato: Preprint
Publicado: 2025
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author Silva, Jadson L. Portela e
Rein, Gabriel
Sousa-Júnior, Sebastião dos A.
Assaad, Fakher F.
Costa, Natanael C.
author_facet Silva, Jadson L. Portela e
Rein, Gabriel
Sousa-Júnior, Sebastião dos A.
Assaad, Fakher F.
Costa, Natanael C.
contents We investigate the two-dimensional optical Su-Schrieffer-Heeger (SSH) model, in which the electron hopping amplitude is modulated by the difference between neighboring phonon coordinates. Using sign-problem-free auxiliary-field quantum Monte Carlo simulations, complemented by mean-field analysis, we determine the long-range ordered phases as a function of the electron-phonon coupling and phonon frequency. By examining both adiabatic and antiadiabatic regimes, we reveal the emergence of staggered and armchair valence bond solid (VBS) phases, as well as the O(4) antiferromagnetic phase. In addition, finite-temperature simulations show that the VBS transition occurs at critical temperatures significantly higher than in models with local electron-phonon coupling, consistent with the presence of lighter polarons in the metallic regime. These findings establish the ground-state and finite-temperature phase diagrams of the optical SSH model, which emphasize its similarities and contrasts with other electron-phonon systems.
format Preprint
id arxiv_https___arxiv_org_abs_2511_02707
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The two-dimensional optical Su-Schrieffer-Heeger model: ground state and thermodynamic properties
Silva, Jadson L. Portela e
Rein, Gabriel
Sousa-Júnior, Sebastião dos A.
Assaad, Fakher F.
Costa, Natanael C.
Strongly Correlated Electrons
We investigate the two-dimensional optical Su-Schrieffer-Heeger (SSH) model, in which the electron hopping amplitude is modulated by the difference between neighboring phonon coordinates. Using sign-problem-free auxiliary-field quantum Monte Carlo simulations, complemented by mean-field analysis, we determine the long-range ordered phases as a function of the electron-phonon coupling and phonon frequency. By examining both adiabatic and antiadiabatic regimes, we reveal the emergence of staggered and armchair valence bond solid (VBS) phases, as well as the O(4) antiferromagnetic phase. In addition, finite-temperature simulations show that the VBS transition occurs at critical temperatures significantly higher than in models with local electron-phonon coupling, consistent with the presence of lighter polarons in the metallic regime. These findings establish the ground-state and finite-temperature phase diagrams of the optical SSH model, which emphasize its similarities and contrasts with other electron-phonon systems.
title The two-dimensional optical Su-Schrieffer-Heeger model: ground state and thermodynamic properties
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2511.02707