Stochastically Realized Observables for Excitonic Molecular Aggregates

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Chemistry

Background:

• Excitonic molecular aggregates are crucial for light-harvesting and optoelectronic devices.
• Traditional methods for calculating their optical properties face computational limitations with increasing system size.

Purpose of the Study:

• To develop and validate a computationally efficient stochastic approach for calculating optical properties of large excitonic molecular aggregates.
• To enable the study of complex systems previously intractable with conventional methods.

Main Methods:

• A novel stochastic method was developed to bypass the limitations of numerically diagonalizing the Frenkel Hamiltonian.
• The method's computational scaling was analyzed, showing significant efficiency gains (N^2 vs N).
• Key observables like optical absorption spectra and density of states were calculated using the stochastic approach.

Main Results:

• The stochastic method accurately reproduces results from traditional diagonalization for small and intermediate systems.
• It enables efficient calculations for large 2D and nanotubular aggregates, up to a million coupled molecules.
• The approach allows for the investigation of spatial correlation effects on optical properties.

Conclusions:

• Stochastic methods provide a computationally feasible pathway for analyzing large excitonic aggregates.
• This methodology facilitates the screening of structural parameters and validation of experimental and theoretical findings.
• The developed approach significantly advances the study of complex molecular aggregates.