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Effects of charge-dependent vibrational frequencies and anharmonicities in transport through molecules

Jens Koch·Felix von Oppen
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Abstract

As a step towards a more realistic modeling of vibrations in single-molecule devices, we investigate the effects of charge-dependent vibrational frequencies and anharmonic potentials on electronic transport. For weak phonon relaxation, we find that in both cases vibrational steps split into a multitude of substeps. This effectively leads to a bias-dependent broadening of vibrational features in current-voltage and conductance characteristics, which provides a fingerprint of nonequilibrium vibrations whenever other broadening mechanisms are secondary. In the case of an asymmetric molecule-lead coupling, we observe that frequency differences can also cause negative differential conductance.

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Jens Koch, Felix von Oppen. 2005-07-30. Effects of charge-dependent vibrational frequencies and anharmonicities in transport through molecules. https://doi.org/10.1103/physrevb.72.113308

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