Quantum Dynamics of Vibrationally-Assisted Electron Transfer beyond Condon approximation in the Ligand-Receptor Complex
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Quantum Physics arXiv:2602.06469 (quant-ph) COVID-19 e-print Important: e-prints posted on arXiv are not peer-reviewed by arXiv; they should not be relied upon without context to guide clinical practice or health-related behavior and should not be reported in news media as established information without consulting multiple experts in the field. [Submitted on 6 Feb 2026] Title:Quantum Dynamics of Vibrationally-Assisted Electron Transfer beyond Condon approximation in the Ligand-Receptor Complex Authors:Muhammad Waqas Haseeb, Mohamad Toutounji View a PDF of the paper titled Quantum Dynamics of Vibrationally-Assisted Electron Transfer beyond Condon approximation in the Ligand-Receptor Complex, by Muhammad Waqas Haseeb and 1 other authors View PDF HTML (experimental) Abstract:We investigate the quantum dynamics of ligand--receptor electron transfer and conformational response in a prototypical viral binding complex, using the SARS-CoV-2 Spike protein bound to the human ACE2 receptor as a model system. Treating the ACE2--Spike interface as an open quantum system embedded in a biological environment, we simulate how vibrational interactions and environmental memory reshape the coupled receptor--ligand dynamics and modulate vibrationally assisted electron transfer (VA-ET). Using a Non-Markovian Stochastic Schr"odinger Equation (NMSSE) approach, we simulate electron transfer between donor and acceptor states in ACE2 modulated by a specific vibrational mode of the Spike protein. The influence of environmental memory (non-Markovian dynamics) and non-Condon effects (vibrational modulation of electronic coupling) are analyzed in detail. In the Markovian limit with an Ohmic bath, population dynamics reduce to exponential kinetics, and extracted transfer rates agree with semiclassical Marcus--Jortner predictions in the appropriate regime. Beyond the Markovian, high-temperature limit, we observe clear deviations: non-exponential decay, coherent oscillatory features, and enhanced sensitivity to the vibrational frequency. Incorporating off-diagonal system--bath coupling alongside diagonal coupling shows that nuclear motion can dynamically gate electron tunneling, sharpening the frequency selectivity of the VA-ET mechanism. Finally, a structured (sub-Ohmic) environmental spectral density with long-lived correlations (``memory'') preserves electronic--vibrational coherence over longer times, amplifying vibrational selectivity under non-Condon coupling. Our results support the proposition that ACE2--Spike binding may exploit vibrational assistance and quantum coherence as a molecular recognition mechanism. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2602.06469 [quant-ph] (or arXiv:2602.06469v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2602.06469 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Muhammad Waqas Haseeb Mr. [view email] [v1] Fri, 6 Feb 2026 07:53:31 UTC (2,633 KB) Full-text links: Access Paper: View a PDF of the paper titled Quantum Dynamics of Vibrationally-Assisted Electron Transfer beyond Condon approximation in the Ligand-Receptor Complex, by Muhammad Waqas Haseeb and 1 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2026-02 References & Citations INSPIRE HEP NASA ADSGoogle Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... Data provided by: Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) 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