The polaron paradigm: a dual coupling effective band model

Abstract

Non-diagonal couplings to a bosonic bath completely change polaronic dynamics, from the usual diagonally-coupled paradigm of smoothly-varying properties. We study, using analytic and numerical methods, a model having both diagonal Holstein and non-diagonal Su-Schrieffer-Heeger (SSH) couplings. The critical coupling found previously in the pure SSH model, at which the $k=0$ effective mass diverges, now becomes a transition line in the coupling constant plane - the form of the line depends on the adiabaticity parameter. Detailed results are given for the quasiparticle and ground state properties, over a wide range of couplings and adiabaticity ratios. The new paradigm involves a destabilization, at the transition line, of the simple Holstein polaron to one with a finite ground-state momentum, but with everywhere a continuously evolving band shape. No 'self-trapping transition' exists in any of these models. The physics may be understood entirely in terms of competition between different hopping terms in a simple renormalized effective band theory. The possibility of further transitions is suggested by the results.

References in corpus (14)

• The numerical renormalization group method for quantum impurity systems
• Quo vadis, cold molecules? - Editorial review
• Fermi-Polaron: Diagrammatic Monte Carlo for Divergent Sign-Alternating Series
• Bold Diagrammatic Monte Carlo: When Sign Problem is Welcome
• Green's function of a dressed particle
• The Green's Function of the Holstein Polaron
• Systematic improvement of the Momentum Average approximation for the Green's function of a Holstein polaron
• Diagrammatic Monte Carlo method for many-polaron problems
• Boson-controlled quantum transport
• Momentum average approximation for models with electron-phonon coupling dependent on the phonon momentum
• Spectral Properties of Holstein and Breathing Polarons
• Quantum-entanglement aspects of polaron systems
• Interplay of Site and Bond Electron-Phonon Coupling in One Dimension
• The effects of non-linear electron-phonon interactions on superconductivity and charge-density-wave correlations

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