Electron-phonon interaction for adiabatic anharmonic phonons

Abstract

A model with Holstein-like electron-phonon coupling is studied in the limit of adiabatic phonons. The phonon distribution is anharmonic with two degenerate maxima. This model can be related to fermions in a correlated binary alloy and describes microscopic phase separation. We discuss the weak and strong electron-phonon coupling limit and present a qualitative phase diagram. In terms of the phononic displacements it consists of a homogeneous, an alternating, and a disordered phase. There is a first order phase transition between the homogeneous and the alternating phase, and second order phase transition between the alternating and the disordered phase. The opening of a gap inside the disordered phase is treated by a dynamical mean-field theory.

11 pages, 3 figures, revised and published version

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Cited by in corpus (5)

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• Frequency splitting of intervalley phonons in graphene
• Charge-density-wave instability in the Holstein model with quartic anharmonic phonons