All-coupling polaron optical response: analytic approaches beyond the adiabatic approximation

Abstract

In the present work, the problem of an all-coupling analytic description for the optical conductivity of the Froehlich polaron is treated, with the goal being to bridge the gap in validity range that exists between two complementary methods: on the one hand the memory function formalism and on the other hand the strong-coupling expansion based on the Franck-Condon picture for the polaron response. At intermediate coupling, both methods were found to fail as they do not reproduce Diagrammatic Quantum Monte Carlo results. To resolve this, we modify the memory function formalism with respect to the Feynman-Hellwarth-Iddings-Platzman (FHIP) approach, in order to take into account a non-quadratic interaction in a model system for the polaron. The strong-coupling expansion is extended beyond the adiabatic approximation, by including into the treatment non-adiabatic transitions between excited polaron states. The polaron optical conductivity that we obtain by combining the two extended methods agree well, both qualitatively and quantitatively, with the Diagrammatic Quantum Monte Carlo results in the whole available range of the electron-phonon coupling strength.

13 pages, 4 figures

References in corpus (4)

• Electron-phonon interaction and charge carrier mass enhancement in SrTiO3
• Diagrammatic Monte Carlo study of the acoustic and the BEC polaron
• On the validity of the Franck-Condon principle in the optical spectroscopy: optical conductivity of the Fröhlich polaron
• Dynamic polaron response from variational imaginary time evolution

Cited by in corpus (3)

• Quasiparticles and phonon satellites in spectral functions of semiconductors and insulators: Cumulants applied to full first principles theory and Fröhlich polaron
• Exact factorization-based density functional theory of electron-phonon systems
• Extending the Feynman variational principle and analytical methods to lattice polarons