Stochastically Realized Observables for Excitonic Molecular Aggregates.
- Author(s): Bradbury, Nadine C
- Chuang, Chern
- Deshmukh, Arundhati P
- Rabani, Eran
- Baer, Roi
- Caram, Justin R
- Neuhauser, Daniel
- et al.
Published Web Locationhttps://doi.org/10.1021/acs.jpca.0c07953
We show that a stochastic approach enables calculations of the optical properties of large 2-dimensional and nanotubular excitonic molecular aggregates. Previous studies of such systems relied on numerically diagonalizing the dense and disordered Frenkel Hamiltonian, which scales approximately as O(N3) for N dye molecules. Our approach scales much more efficiently as O(Nlog(N)), enabling quick study of systems with a million of coupled molecules on the micrometer size scale. We calculate several important experimental observables, including the optical absorption spectrum and density of states, and develop a stochastic formalism for the participation ratio. Quantitative agreement with traditional matrix diagonalization methods is demonstrated for both small- and intermediate-size systems. The stochastic methodology enables the study of the effects of spatial-correlation in site energies on the optical signatures of large 2D aggregates. Our results demonstrate that stochastic methods present a path forward for screening structural parameters and validating experiments and theoretical predictions in large excitonic aggregates.