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Updated: May 9, 2026

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
On the parameterization of vibronic Hamiltonians for molecular aggregates using absorption line-shapes as an input
C Brüning1, K Renziehausen, V Engel
1Universität Würzburg, Institut für Physikalische und Theoretische Chemie, Am Hubland, Campus Nord, Emil-Fischer-Str. 42, 97074 Würzburg, Germany.
Abstract:
Absorption line-shapes of molecular aggregates are often calculated using a simple form for a vibronic Hamiltonian. Parameters which enter into the model are usually taken from measured spectra. Here, we address the question in how far different sets of input parameters used to calculate the spectra lead to similar spectral features. Therefore, we first present analytical expressions which illustrate the relation between the various parameters such as Huang-Rhys factors, electronic coupling elements, and aggregate size. Numerical calculations show that identical peak ratios and spectra can be obtained for different sets of parameters. This illustrates the basic difficulties in extracting reliable molecular information from a comparison of calculated and measured spectra.
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