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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 15: Emerging Topics in Chemical and Polymer Physics, New Instruments and Methods II
CPP 15.7: Vortrag
Montag, 9. März 2026, 18:45–19:00, ZEU/0255
Towards Theoretical UV/Vis Spectra with Experimental Accuracy - Functional Errors and Thermal Broadening — •Robert Strothmann1, Johannes T. Margraf2, and Karsten Reuter1 — 1Fritz-Haber-Institut, Berlin, Germany — 2University of Bayreuth, Bayreuth, Germany
First principles methods like time-dependent density-functional theory (TD-DFT) can be used to predict molecular UV/Vis spectra relying on a number of approximations such as the choice of functionals, the description of solvation, as well as the treatment of thermal broadening. For the latter, simple (smeared) line spectra or structural ensembles obtained within the harmonic approximation are the most common choices. With the rise of machine learning interatomic potentials (MLIP) prohibitively costly ab initio molecular dynamics (MD) simulations can be replaced with similarly accurate MLIP MDs. This allows a detailed comparison of these approaches for a large number of systems for the first time.
In this talk, we benchmark predicted UV/Vis spectra against experimental references. To this end, the agreement with a curated set of literature reported spectra for diverse organic molecules in various solvents is assessed in terms of full spectral overlap, beyond a "peak to peak" comparison. We emphasize the influence of functional choice and thermal sampling approaches (e.g. harmonic vs. anharmonic), as well as the role of different conformers. How important each of these effects is and how it affects computational cost will be studied with the goal of providing best practise guidelines.
Keywords: UV/Vis Spectroscopy; Machine-learned Interatomic Potential