The Power of TDDFT in Real-Time and Real-Space: From Light Harvesting to Photoemission
ORAL · Invited
Abstract
Solving the time-dependent equations of Kohn-Sham or generalized Kohn-Sham theory by propagation in real time on a grid in real space is a powerful approach for calculating electronic excitations. The technique is ideally suited for studying large systems and long-range charge-transfer phenomena due to its excellent parallelization. We here discuss two example of electron dynamics that can excellently be described with the real-time and real-space technique. First, we discuss how to simulate photoemission as a process in real time. When a system is excited by an electromagnetic field of sufficient frequency, it can emit electrons. We simulate the emission of the outgoing wave packet in real time and calculate the corresponding kinetic energy spectrum. In this way, angular resolved photoemission signals can be calculated. Challenging phenomena, like pump-probe photoemission mapping excited states and circular dichroism in the angular distribution of the emitted electrons are thus obtained in close agreement with experiments. Second, we discuss how the energy-transfer processes that occur in natural light-harvesting systems can be studied via real-space and real-time techniques. We demonstrate in calculations for the antenna complexes of photosynthetic bacteria how one can extract just from the time-dependent density information about how energy is transported between the chromophores and thus efficiently collected.
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Publication: S. Hammon and S. Kümmel, Pump-probe photoemission simulated in real time: Revealing many-particle signatures,<br>Phys. Rev. A 104, 012815 (2021)<br><br>J. Kehrer et al., Self-interaction correction, electrostatic, and structural influences on time-dependent density functional theory excitations of bacteriochlorophylls from the light-harvesting complex 2, J. Chem. Phys. 153, 144114 (2020)<br><br>I. Schelter et al., Assessing density functional theory in real-time and real-space as a tool for studying bacteriochlorophylls and the light-harvesting complex 2, J. Chem. Phys. 151, 134114 (2019)<br><br>I. Schelter and S. Kümmel, Accurate Evaluation of Real-Time Density Functional Theory Providing Access to Challenging Electron Dynamics, Journal of Chemical Theory and Computation 14 (2018)
