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Benchmarking mixed quantum-classical molecular dynamics for electronic strong coupling
Arun Kumar Kanakati1, Oriol Vendrell2, Gerrit Groenhof1
1Nanoscience Center and Department of Chemistry, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland.
The Journal of Chemical Physics
|July 23, 2026
Summary
Semi-classical methods accurately model cavity-enhanced molecular dynamics. Fewest-Switches Surface Hopping (FSSH) with decoherence correction best matches quantum dynamics for strong light-matter coupling.
Area of Science:
- Quantum Chemistry and Photochemistry
- Theoretical and Computational Chemistry
- Spectroscopy and Light-Matter Interactions
Background:
- Collective coupling of molecular ensembles to optical cavities alters excited-state dynamics and reactivity.
- Accurate simulation of these cavity-induced effects requires atomic resolution, necessitating advanced computational methods.
- Existing semi-classical molecular dynamics approaches treat nuclear motion classically and light-matter interactions quantum mechanically.
Purpose of the Study:
- To benchmark the accuracy of different semi-classical methods for simulating nonadiabatic dynamics in strongly coupled molecular systems.
- To compare mixed quantum-classical approaches, specifically Ehrenfest dynamics and Fewest-Switches Surface Hopping (FSSH), against exact quantum dynamics.
- To assess the reliability of these methods for studying photochemistry in optical cavities.
Main Methods:
- Employed semi-classical molecular dynamics simulations, including Ehrenfest dynamics and FSSH.
- Utilized the multi-configuration time-dependent Hartree (MCTDH) method for numerically exact quantum dynamics simulations.
- Focused on simulating the nonadiabatic dynamics of electronically strongly coupled carbon monoxide molecules in an optical cavity.
Main Results:
- Semi-classical methods qualitatively reproduced the features of full quantum dynamics.
- FSSH, when augmented with a decoherence correction, demonstrated the best quantitative agreement with exact quantum simulations.
- The Tavis-Cummings framework was used to describe collective light-matter interactions.
Conclusions:
- Mixed quantum-classical methods offer a computationally efficient and reliable alternative to full quantum treatments for complex systems.
- FSSH with decoherence correction is a promising approach for investigating nonadiabatic photochemistry under strong coupling conditions.
- These findings enable the study of cavity quantum electrodynamics effects in molecular systems beyond the scope of exact quantum calculations.
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