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Updated: Apr 16, 2026
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Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
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Exciton dispersion in molecular solids.
Pierluigi Cudazzo1, Francesco Sottile, Angel Rubio
1Nano-Bio Spectroscopy group, Universidad del País Vasco, CFM CSIC-UPV/EHU-MPC and DIPC, E-20018 San Sebastián, Spain. European Theoretical Spectroscopy Facility (ETSF.
Summary
Investigating exciton dispersion in molecular solids reveals exciton character, from localized Frenkel to delocalized Wannier-Mott types. This analysis links electronic band dispersion and electron-hole interactions to exciton nature.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Computational Chemistry
Background:
- Exciton dispersion is key to understanding electronic properties in molecular solids.
- Characterizing excitons helps differentiate between localized (Frenkel) and delocalized (Wannier-Mott) states.
- Molecular solids like picene, pentacene, tetracene, and coronene serve as model systems.
Purpose of the Study:
- To investigate exciton dispersion in prototypical molecular solids.
- To identify the exciton character by analyzing energy dependence on electron-hole pair momentum.
- To elucidate the interplay between electronic structure and exciton properties.
Main Methods:
- Parameter-free solution of the many-body Bethe-Salpeter equation.
- Application of many-body perturbation theory.
- Analysis of exciton energy as a function of momentum.
Main Results:
- Demonstrated the link between exciton dispersion and exciton character (Frenkel vs. Wannier-Mott).
- Discussed exciton mixing and Davydov splitting using many-body perturbation theory.
- Established the crucial role of electronic band dispersion and electron-hole interaction in determining exciton nature.
Conclusions:
- Exciton dispersion analysis is a powerful tool for classifying exciton types in molecular solids.
- The study provides a theoretical framework connecting microscopic interactions to macroscopic exciton behavior.
- Findings are applicable to other systems with localized electron wavefunctions, including strongly correlated insulators.
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