Surface hopping simulations show valley depolarization driven by exciton-phonon resonance
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866918413699383296 |
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| author | Krotz, Alex Tempelaar, Roel |
| author_facet | Krotz, Alex Tempelaar, Roel |
| contents | Resonances between excitonic transitions and nuclear coordinates have been shown to drive a variety of excited-state dynamical phenomena in molecular systems. Here, we report mixed quantum--classical simulations showing similar resonances to primarily contribute to valley depolarization in monolayer MoS$_2$. The applied simulation framework combines reciprocal-space surface hopping with microscopic models of the quasiparticle band structure, electron--hole interactions, and carrier--phonon interactions, parametrized against ab initio calculations. This enables low-cost excited-state dynamics simulations that are microscopic, non-Markovian, and non-perturbative in the carrier--phonon interaction. The framework furthermore retains explicit information on transient phonon occupancies, through which we show a resonance between the dominant optical phonon branch and the lowest exciton band to largely drive valley depolarization, by activating a Maialle--Silva--Sham mechanism. Resulting valley polarization times are consistent with experimental measurements across temperatures. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2505_06953 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Surface hopping simulations show valley depolarization driven by exciton-phonon resonance Krotz, Alex Tempelaar, Roel Materials Science Mesoscale and Nanoscale Physics Chemical Physics Quantum Physics Resonances between excitonic transitions and nuclear coordinates have been shown to drive a variety of excited-state dynamical phenomena in molecular systems. Here, we report mixed quantum--classical simulations showing similar resonances to primarily contribute to valley depolarization in monolayer MoS$_2$. The applied simulation framework combines reciprocal-space surface hopping with microscopic models of the quasiparticle band structure, electron--hole interactions, and carrier--phonon interactions, parametrized against ab initio calculations. This enables low-cost excited-state dynamics simulations that are microscopic, non-Markovian, and non-perturbative in the carrier--phonon interaction. The framework furthermore retains explicit information on transient phonon occupancies, through which we show a resonance between the dominant optical phonon branch and the lowest exciton band to largely drive valley depolarization, by activating a Maialle--Silva--Sham mechanism. Resulting valley polarization times are consistent with experimental measurements across temperatures. |
| title | Surface hopping simulations show valley depolarization driven by exciton-phonon resonance |
| topic | Materials Science Mesoscale and Nanoscale Physics Chemical Physics Quantum Physics |
| url | https://arxiv.org/abs/2505.06953 |