Dresden 2020 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 3: Molecular Electronics and Excited State Properties I

CPP 3.2: Talk

Monday, March 16, 2020, 09:45–10:00, ZEU 260

Electronic excitations of bacteriochlorophyll with ab initio Green's function-based many-body perturbation theory — •Zohreh Hashemi and Linn Leppert — Institute of Physics, University of Bayreuth, 95440 Bayreuth, Germany

Bacteriochlorophyll (BCL) molecules are one of the main pigments responsible for excitation energy transfer and charge separation in bacterial photosynthesis. Accurate calculation of their electronic structure and excited states from first principles, is a necessary prerequisite for simulating these processes without employing empirical parameters.

Here we present a comprehensive study of charged and neutral excitations in free-standing BCLa, as found in the Light Harvesting 2 complex of the purple bacterium Rhodobacter sphaeroides. We evaluate the accuracy of Green's function-based many-body perturbation theory within the GW+Bethe-Salpeter equation (BSE) approach and time-dependent density functional theory (TDDFT), and benchmark to theoretical values and experimental data. Furthermore, we discuss the importance of numerical convergence and partial self-consistency in the GW approach, and the role of the exchange-correlation functional used in our TDDFT calculations and as starting point for constructing zeroth order approximations to the one-particle Green's function G and the screened Coulomb interaction W.