Vibrational Instabilities in Charge Transport through Molecular Nanojunctions: The Role of Nonconservative Current-Induced Electronic Forces
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arXiv
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| Auteurs principaux: | , , , |
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| Format: | Preprint |
| Publié: |
2025
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| _version_ | 1866908283945615360 |
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| author | Mäck, Martin Preston, Riley J. Thoss, Michael Rudge, Samuel L. |
| author_facet | Mäck, Martin Preston, Riley J. Thoss, Michael Rudge, Samuel L. |
| contents | Understanding the current-induced vibrational dynamics in molecular nanojunctions is critical for gaining insight into the stability of such systems. While it is well known that Joule heating at higher bias voltages plays an important role for the stability of the nanojunction, a different mechanism caused by current-induced nonconservative forces has been reported to cause vibrational instabilities already at much lower voltages. In this paper, we apply a mixed quantum-classical approach based on electronic friction and Langevin dynamics to a model system for which vibrational instabilities have previously been reported. The electronic friction and other electronic forces can be calculated exactly using nonequilibrium Green's functions. We perform Langevin simulations of the vibrational dynamics to calculate the steady-state vibrational excitation and compare the results to a simplified eigenmode analysis, identifying the parameter regimes in which runaway modes appear. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_19773 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Vibrational Instabilities in Charge Transport through Molecular Nanojunctions: The Role of Nonconservative Current-Induced Electronic Forces Mäck, Martin Preston, Riley J. Thoss, Michael Rudge, Samuel L. Mesoscale and Nanoscale Physics Chemical Physics Understanding the current-induced vibrational dynamics in molecular nanojunctions is critical for gaining insight into the stability of such systems. While it is well known that Joule heating at higher bias voltages plays an important role for the stability of the nanojunction, a different mechanism caused by current-induced nonconservative forces has been reported to cause vibrational instabilities already at much lower voltages. In this paper, we apply a mixed quantum-classical approach based on electronic friction and Langevin dynamics to a model system for which vibrational instabilities have previously been reported. The electronic friction and other electronic forces can be calculated exactly using nonequilibrium Green's functions. We perform Langevin simulations of the vibrational dynamics to calculate the steady-state vibrational excitation and compare the results to a simplified eigenmode analysis, identifying the parameter regimes in which runaway modes appear. |
| title | Vibrational Instabilities in Charge Transport through Molecular Nanojunctions: The Role of Nonconservative Current-Induced Electronic Forces |
| topic | Mesoscale and Nanoscale Physics Chemical Physics |
| url | https://arxiv.org/abs/2503.19773 |