Langevin simulations of a long-range electron-phonon model
- Univ. Côte d'Azur, Nice (France); CNRS-UCA-SU-NUS-NTU International Joint Research Unit (Singapore); National Univ. of Singapore (Singapore); Beijing Computational Science Research Center (China); DOE/OSTI
- Univ. of California, Davis, CA (United States)
We present a quantum Monte Carlo (QMC) study, based on the Langevin equation, of a Hamiltonian describing electrons coupled to phonon degrees of freedom. The bosonic part of the action helps control the variation of the field in imaginary time. As a consequence, the iterative conjugate gradient solution of the fermionic action, which depends on the boson coordinates, converges more rapidly than in the case of electron-electron interactions, such as the Hubbard Hamiltonian. Fourier acceleration is shown to be a crucial ingredient in reducing the equilibration and autocorrelation times. After describing and benchmarking the method, we present results for the phase diagram focusing on the range of the electron-phonon interaction. Furthermore, we delineate the regions of charge density wave formation from those in which the fermion density is inhomogeneous, caused by phase separation. We show that the Langevin approach is more efficient than the determinant QMC method for lattice sizes N ≳ 8 × 8 and that it therefore opens a potential path to problems including, for example, charge order in the three-dimensional Holstein model.
- Research Organization:
- Univ. of California, Davis, CA (United States)
- Sponsoring Organization:
- USDOE; USDOE Office of Science (SC)
- Grant/Contract Number:
- SC0014671
- OSTI ID:
- 1612257
- Journal Information:
- Physical Review. B, Journal Name: Physical Review. B Journal Issue: 3 Vol. 99; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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