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BP: Fachverband Biologische Physik

BP 2: Computational Biophysics I

BP 2.11: Talk

Monday, March 9, 2026, 12:15–12:30, BAR/0106

Insights into Quantum Decoherence in Biological Light Harvesting from First-Principles Simulations — Thomas Trepl, •Ingo Schelter, Johannes M. Foerster, and Stephan Kümmel — University of Bayreuth, Bayreuth, Germany

Photosynthesis is a fascinating process of outstanding importance since it provides the energy for most life on Earth. Considering the remarkable quantum efficiency with which the energy of absorbed photons is transferred in the initial light-harvesting step, there exists a long-standing speculation about the role of quantum coherence.

In this talk, I show the decoherence and localization of excitation energy that evolves from the coupled electron and nuclear dynamics in the B850 ring at room temperature after an initial Laser excitation as typically used in an experiment. The electron dynamics of the whole multichromophoric system is described by the real-time formulation of time-dependent density functional theory. The nuclear dynamics is treated by Ehrenfest dynamics, allowing for a non-adiabatic coupling between electrons and nuclei. The simulations show that nuclear dynamics starts to trigger quantum decoherence after only a few tens of femtoseconds.

Keywords: Photosynthesis; Excitation energy transfer; Time dependent density functional theory; Molecular dynamics; First-principles calculations