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Updated: Jun 1, 2026

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
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Published on: May 27, 2020

Chiroptics of In-Plane Excitons.

Sophia Sburlati1, Afton Gustafson1, Bart Kahr1

  • 1Department of Chemistry, New York University, 29 Washington Place, New York, New York 10003, United States.

The Journal of Physical Chemistry. A
|May 31, 2026
PubMed
Summary
This summary is machine-generated.

This study reveals how magnetic dipole and electric quadrupole moments influence chiroptical activity, extending the exciton chirality method. Analyzing polyyne dimers clarifies the role of multipolar responses in coupled excited states.

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Area of Science:

  • Physical Chemistry
  • Computational Chemistry
  • Spectroscopy

Background:

  • The exciton chirality method links chiroptical activity to absolute stereochemistry.
  • Current methods often overlook magnetic dipole and electric quadrupole transition moments.
  • These higher-order moments are crucial for a complete understanding of chiroptical phenomena.

Purpose of the Study:

  • To investigate the role of multipolar transition moments in chiroptical activity.
  • To extend the applicability of the exciton chirality method.
  • To analyze the behavior of coupled excited states in polyyne systems.

Main Methods:

  • In silico modeling of C18H2 polyyne dimers with varying geometries.
  • Calculation of gyration and rotatory strength tensors.
  • Analysis of multipolar response in coupled excited states.

Main Results:

  • Chiroptical response is primarily governed by exciton states.
  • Maximum responses observed for intermediate geometries.
  • Multipolar contributions are reconciled with transition moments derived from molecular structure.

Conclusions:

  • Magnetic dipole and electric quadrupole moments play essential roles in chiroptical activity.
  • The exciton chirality method can be extended by considering these higher-order moments.
  • Symmetry-breaking perturbations establish a link between planar and chiral systems.