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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 52: Focus Session: Ultrafast Processes in Organic Semiconductors and Perovskites III (joint session O/CPP)
CPP 52.1: Talk
Friday, March 22, 2024, 10:30–10:45, MA 004
Unveiling ultrafast vibronic dynamics in organic chromophores from first principles — •Michele Guerrini1, Jannis Krumland1,2, and Caterina Cocchi1,2 — 1Physics Department and Center for Nanoscale Dynamics(CeNaD), Carl von Ossietzky Universität Oldenburg, Germany — 2Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Germany
Identifying and quantifying the interplay between electron and nuclear dynamics in the excited state of organic molecules is of paramount importance to unveil and interpret their complex photophysics upon ultrafast excitation. In this work, we investigate from first principles the ultrafast vibronic dynamics of p-coumaric acid chromophore [1]. We start off the simulations in excited states corresponding to bright or dark transitions. By monitoring the kinetic energy spectral density [2] and the population dynamics, we analyze the characteristics of the electron-nuclear motion and its evolution over a time window of 300 fs. We observe that anharmonic and non-adiabatic effects are particularly pronounced in excitations with charge-transfer character and lead to instabilities with the eventual distortion of the system. On the other hand, the dynamics initialized from bright excited states with delocalized character remains electronically and structurally stable, and the resulting nuclear motion is markedly harmonic.
[1] Theor. Chem. Acc. 142, 110 (2023)
[2] J. Phys. Chem. A, 125, 9619 (2021)
Keywords: ultrafast dynamics; real-time time dependent DFT; organic chromophore; vibronic dynamics