Regensburg 2010 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 9: Focus Session: Structural dynamics in photoexcited molecules

DF 9.6: Topical Talk

Mittwoch, 24. März 2010, 12:20–12:40, H11

Ab-initio and semi-empirical molecular dynamics studies of photo-isomerisable molecules — •Jan Boyke Schönborn, Ole Carstensen, and Bernd Hartke — Christian-Albrechts-University Kiel, Germany

Due to the ongoing trend to miniaturization the interest in molecular scale switches is growing fastly. Fulgides and Azobenzenes are promising systems for future applications. The talk is going to present recent theoretical results on the photochemical properties and dynamics of derivatives of the aforementioned molecules. After careful evaluation by comparison to high level ab-initio data (CASSCF/CASPT2), different semi-empirical multireference methods have been used in ab-initio molecular dynamics simulations to get a deepened understanding of the ultrafast switching processes. Transient spectra covering a wavelength range of 500 nm and a time period of 1500 fs have been simulated, including 3-5 electronically excited states. The excellent agreement of these simulated spectra with the experimental ones allows for a confident interpretation in terms of mechanistic details. An in-depth analysis of the calculated trajectories indicates that even seemingly minor modifications of the functional groups play major roles in the control of the switching dynamics. Possible ways of simulating switchable molecules embedded in bulk soft matter are discussed briefly.