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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 15: Poster Session I
CPP 15.3: Poster
Montag, 17. März 2025, 19:00–21:00, P4
Towards Theoretical UV/Vis Spectra with Experimental Accuracy. Benchmarks for Spiropyran Photoswitches — •Robert Strothmann1, Johannes T. Margraf2, and Karsten Reuter1 — 1Fritz-Haber-Institut der MPG, Berlin — 2University of Bayreuth
Molecular photoswitches are molecules that undergo an isomerization upon irradiation with specific wavelengths. One key feature for understanding this process are the UV/Vis spectra of the involved species (e.g. the closed and open forms in the case of spiropyran, SP). First-principles methods like density-functional theory (DFT) allow the calculation of UV/Vis spectra within certain approximations. However, the properties of the chosen functional, the description of solvation, as well as the accuracy of conformational and vibrational sampling all contribute to discrepancies between theory and experiment. This motivates us to establish a rigorous theoretical approach to assist in the prediction and analysis of UV/Vis spectra for molecular photoswitches. As a crucial step, we here benchmark different approaches for predicting UV/Vis spectra of SP switches against experimental references. We emphasize the influence of different functional approximations and highlight the role of the conformational ensemble and molecular vibrations sampling (e.g. via by machine learning enhanced molecular dynamics simulations). The importance of these different effects is discussed, with the goal of providing best practice guidelines that enable robust predictions.
Keywords: Absorption Spectra; Photoswitches; Density Functional Theory; Theoretical Spectroscopy