The optical absorption of the Frohlich polaron model is obtained by an approximation-free diagrammatic Monte Carlo method and compared with two new approximate approaches that treat lattice relaxation effects in different ways. We show that: (i) a strong coupling expansion, based on the Franck-Condon principle, well describes the optical conductivity for large coupling strengths (alpha > 10); (ii) a memory function formalism with phonon broadened levels reproduces the optical response for weak coupling strengths (alpha < 6) taking the dynamic lattice relaxation into account. In the coupling regime 6 <alpha < 10, the optical conductivity is a rapidly changing superposition of both Franck-Condon and dynamic contributions.

Validity of the Franck-Condon principle in the optical spectroscopy: Optical conductivity of the Frohlich polaron

De Filippis G;
2006

Abstract

The optical absorption of the Frohlich polaron model is obtained by an approximation-free diagrammatic Monte Carlo method and compared with two new approximate approaches that treat lattice relaxation effects in different ways. We show that: (i) a strong coupling expansion, based on the Franck-Condon principle, well describes the optical conductivity for large coupling strengths (alpha > 10); (ii) a memory function formalism with phonon broadened levels reproduces the optical response for weak coupling strengths (alpha < 6) taking the dynamic lattice relaxation into account. In the coupling regime 6
2006
INFM
INTERMEDIATE-VALENCE
SLOW ELECTRONS
GROUND-STATE
ABSORPTION
CRYSTAL
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/156401
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