Stability of Holstein and Fröhlich bipolarons

Chakraborty, Mou; Min, B. I.; Chakrabarti, Atisdipankar; Das, Anindita

doi:10.1103/physrevb.85.245127

Cited by 13 publications

(38 citation statements)

References 14 publications

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“…Figure 1 shows that |U C (λ)| > |Ū C (λ)| for all λ. This means that the phonon-mediated interaction is in fact strongly repulsive, in stark contrast to what is observed for conventional polaron models [63,64,68]. This surprising result can be explained by considering the limit Ω |t|, |g| within perturbation theory (details in Supplementary Information).…”

mentioning

confidence: 90%

“…Methods: We use two methods to investigate this problem. The first is variational exact diagonalization (VED), a well-established, unbiased numerical method, where the variational basis set is expanded systematically, starting from the Bloch state for two adjacent particles and zero phonons [62][63][64]. The second method is based on the Momentum Average (MA) approximation, a quasianalytical variational method that has been shown to be accurate for polarons [65][66][67], including SSH polarons [21].…”

mentioning

confidence: 99%

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Phonon-mediated repulsion, sharp transitions and (quasi)self-trapping in the extended Peierls-Hubbard model

Sous

Chakraborty

Adolphs

et al. 2017

Sci Rep

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We study two identical fermions, or two hard-core bosons, in an infinite chain and coupled to phonons by interactions that modulate their hopping as described by the Peierls/Su-Schrieffer-Heeger (SSH) model. We show that exchange of phonons generates effective nearest-neighbor repulsion between particles and also gives rise to interactions that move the pair as a whole. The two-polaron phase diagram exhibits two sharp transitions, leading to light dimers at strong coupling and the flattening of the dimer dispersion at some critical values of the parameters. This dimer (quasi)self-trapping occurs at coupling strengths where single polarons are mobile. This illustrates that, depending on the strength of the phonon-mediated interactions, the coupling to phonons may completely suppress or strongly enhance quantum transport of correlated particles.

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confidence: 90%

mentioning

confidence: 99%

Phonon-mediated repulsion, sharp transitions and (quasi)self-trapping in the extended Peierls-Hubbard model

Sous

Chakraborty

Adolphs

et al. 2017

Sci Rep

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“…In order to get a convergent basis for small polaron (ω=5.0 and g=2.0) we have appropriated the idea of Lang-firsov transformation while constructing the basis. 10,11,14 This method works very well for the case of small polarons as has been established by earlier works as it incorporates into the basis the important states which a small polaron requires. 10,11,14 We calculate the following quantities of interest: To calculate the correlation between the electron position and phonon distribution (lattice deformation) in the ground state, we define a correlation function as follows:…”

Section: The Modelmentioning

confidence: 86%

Orbital effects of strong magnetic field on a two-dimensional Holstein polaron

Pradhan¹,

Chakraborty²,

Taraphder³

2016

Phys. Rev. B

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We investigate the orbital effects of strong external magnetic field on the ground state properties of a two dimensional holstein polaron, employing variational approaches based on the exact diagonalization (VAED). From the ground state energy and the wave function we calculate electron-phonon correlation function, the average phonon number and the Drude weight and investigate the evolution of a 2D holstein polaron as a function of the magnetic flux. Although the external magnetic field affects the polaron throughout the parameter regime, we show that the magnetic field has a stronger effect on a loosely bound (spatially extended) polaron. We also find that the magnetic field can be used as a tuning parameter, particularly for weakly coupled polaron, to reduce the spatial extent of a large polaron.

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“…All translations of these states on the infinite lattice are included. Hereafter, we refer to such variational approaches based on exact diagonalization as VED [35][36][37][38][39][40][41][42] . We will also apply a self-consistent VED (SC-VED) scheme, which has successfully been used to investigate the (extended) Holstein model 38,39 .…”

Section: Numerical Approachmentioning

confidence: 99%

“…Since the microscopic structure of the Edwards polaron is rather diverse, withdepending on the model parameters-lattice polaron or spin polaron characteristics, we utilize a self-consistent variational numerical diagonalization technique [35][36][37][38][39] to address this issue in one to three spatial dimensions. Due to the huge bosonic Hilbert space, the dimensionality effects on the Edwards polaron problem have not been studied before.…”

Section: Introductionmentioning

confidence: 99%

Edwards polaron formation : From one to three dimensions

Chakraborty¹,

Mohanta²,

Taraphder³

et al. 2016

Phys. Rev. B

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Employing a self-consistent (optimized) variational diagonalization scheme we investigate the formation of polaronic quasiparticles in a spinless fermion-boson transport model that couples the movement of charge carriers to fluctuations and correlations of a background medium. The background is parameterized by bosonic degrees of freedom. The variational fermion-boson Hilbert space is constructed to achieve high accuracy in one to three spatial dimensions with modest computational requirements. To characterize the ground-state properties of the Edwards model in the single-particle sector, we present exact numerical results for the polaron band dispersion, quasiparticle weight, Drude weight, mass enhancement, and the particle-boson correlations in a wide parameter regime. In the Edwards model, transport will be quasi-free, diffusive or boson-assisted in the weakly fermion-boson coupled, fluctuation-dominated or strongly correlated regimes, respectively. Thereby correlated transport is not only assisted but also limited by the bosonic excitations. As a result, the Drude weight remains finite even in the limit of very small boson frequencies. For a strongly correlated background, closed loops are important, in any dimension, to generate a finite effective particle mass even when the free fermion has an infinite mass.

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Stability of Holstein and Fröhlich bipolarons

Cited by 13 publications

References 14 publications

Phonon-mediated repulsion, sharp transitions and (quasi)self-trapping in the extended Peierls-Hubbard model

Phonon-mediated repulsion, sharp transitions and (quasi)self-trapping in the extended Peierls-Hubbard model

Orbital effects of strong magnetic field on a two-dimensional Holstein polaron

Edwards polaron formation : From one to three dimensions

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