Dr. Fulu Zheng
Universität Bremen
spricht zum Thema
Modeling of quantum dynamics in large-scale open quantum systems with Davydov Ansätze
Abstract:
It has long been a challenge to accurately and efficiently simulate exciton–phonon dynamics in large open quantum systems with a fully quantum mechanical treatment due to extensive computational resources required. Treating phonons on the same footing as excitons, Davydov trial states can tackle this seemingly intractable problem combined with the Dirac–Frenkel time-dependent variational method. In this talk, I will introduce the framework of this methodology using an exemplary application on describing the exciton diffusion in mesoscale 1D and 2D nanoarrays of B850 pigments from the light harvesting 2 complexes of purple bacteria. By implementing the algorithm in graphic processing units, we successfully simulated the coupled exciton–phonon dynamics in a system containing more than 1600 molecules. The superradiance enhancement factor extracted from the simulations indicates an exciton delocalization over two to three pigments. Beyond the single versions of the Davydov Ansatz, Zhao and co-workers have proposed the multiple Davydov Ansätze, which are linear superpositions of the single Davydov trial states. These multiple Davydov Ansätze, in principle, can produce an exact solution to the Schrödinger equation in the limit of large multiplicities. A brief introduction to the multiple Davydov Ansätze will also be covered in the talk, in company with a short review on recent applications of this method.
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Professor Dr. Kühn