Polaronic optical absorption of the Holstein and Su-Schrieffer-Heeger models

M. Capone; W. Stephan

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arXiv · cond-mat/9607179

Polaronic optical absorption of the Holstein and Su-Schrieffer-Heeger models

M. Capone·W. Stephan

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Abstract

The optical conductivity of a polaronic charge carrier in the intermediate and strong-coupling regimes is calculated for a tight-binding electron using exact diagonalization. Two different simple models of the electron-phonon coupling are considered: the Holstein model, with coupling of the lattice displacement to the local electron density, and the Su-Schrieffer-Heeger type of coupling arising from modulation of the electronic overlap integral. The two models are shown to exhibit a similar polaronic absorption band. However, the Su-Schrieefer-Heeger form of coupling gives rise to a second strong absorption band not present in the Holstein model. This additional feature corresponds to transitions from the ground state of bonding character on a shortened bond to excited states of anti-bonding character on the same shortened bond.

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M. Capone, W. Stephan. 1996-07-25. Polaronic optical absorption of the Holstein and Su-Schrieffer-Heeger models. https://arxiv.org/abs/cond-mat/9607179

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